THE PROCEEDINGS OF THE INTERNATIONAL
WORKSHOP ON MEDITERRANEAN CARTILAGINOUS FISH
WITH EMPHASIS ON SOUTHERN AND EASTERN
MEDITERRANEAN
14-16 October 2005
Ataköy Marina
Istanbul - TURKEY
Edited by
Nuri BAŞUSTA
Çetin KESKİN
Fabrizio SERENA
Bernard SERET
All rights reserved. No part of this publication may be reproduced, stored in a retrieval
system or transmitted in any form or by any means without the prior permission from
the Turkish Marine Research Foundation (TÜDAV).
The finding, interpretations, and conclusions expressed in this publication are entirely
those of authors and should not be attributed in any manner to the Turkish Marine
Research Foundation (TÜDAV). Texts are as originally submitted.
Citation:
BAŞUSTA, N., KESKİN, Ç., SERENA, F., SERET, B. (Eds.), 2006.
“The Proceedings of the Workshop on Mediterranean Cartilaginous Fish
with Emphasis on Southern and Eastern Mediterranean”
Turkish Marine Research Foundation. Istanbul- TURKEY.
Publication Number: 23
Copyright:
Türk Deniz Araştırmaları Vakfı (Turkish Marine Research Foundation).
ISBN 975-8825-13-5
Avaible from: Türk Deniz Araştırmaları Vakfı – Turkish Marine Research Foundation
(TÜDAV)
P.O. Box 10 Beykoz / ISTANBUL – TURKEY
Tel: + 90 216 424 07 72
Fax: + 90 216 424 07 71
Web: www.tudav.org
e-mail: tudav@superonline.com
Cover pictures: Dasyatis pastinaca (up left) by Ateş EVİRGEN
Carcharhinus plumbeus (up right) by Hasan LAFÇI
Scyliorhinus stellaris (bottom) by Bayram ÖZTÜRK
Printed by: Grapis Dijital Tel: +90 212 629 06 07
CONTENTS
Page
Preface .................................................................................................................................. I
Population Parameters of Spiny Dogfish, Squalus acanthias from the
Turkish Black Sea Coast and Its Commercial Exploitation in Turkey
Düzgüneş, E., Okumuş, I., Feyzioglu, M., Sivri, N...........................................................1
Seasonal Variation of Hysterothylacium Aduncum Infection in the
Common Guitarfish, Rhinobatos rhinobatos in Iskenderun Bay
(North-Easthern Mediterranean Sea) Turkey
Genç, E., Yıldırım, Y. B., Basusta, N., Çekiç, M. .............................................................10
Some Biological Aspects of the Lesser Spotted Dogfish Scyliorhinus
canicula (Linnaeus, 1758) in Edremit Bay (The Northern Aegean
Sea) Turkey
Türker Çakır, D., Torcu Koç, H., Erdoğan, Z. ................................................................17
Difficulties in Age Readings from Dorsal Spines of Spiny
Dogfish Squalus acanthias L., 1758
Demirhan, S. A., Öğüt, H., Engin, S., Başusta, N, Genç, E. ...........................................28
Sediment Structure and Occurrence of Skates and Rays Inhabiting
in Babadillimani Bight Located in Northeastern Mediterranean
Yeldan, H., Avşar, D. .........................................................................................................35
Save the Sandbar Sharks of Boncuk Bay, Turkey
Öztürk, B. ............................................................................................................................42
Sexual Dimorphism in the Head, Mouth and Body Morphology of
the Lesser-Spotted Dogfısh, Scyliorhinus canicula, from Turkey
Filiz, H., Taşkavak, E. ........................................................................................................48
Food of Lesser Spotted Dogfish, Scyliorhinus canicula (Linnaeus, 1758),
in Foca (The Northeast Aegean Sea, Turkey) in Autumn 2002
Filiz, H.,Taşkavak, E. .........................................................................................................60
Preliminary Results on Depth Distribution of Cartilaginous Fish in the
North Aegean Sea and their Fishing Potential in Summer 2001
Keskin, Ç., Karakulak, F. S. ..............................................................................................69
The Production and Economic Importance of Sharks in Turkey
Doğan, K..............................................................................................................................79
Page
Iago Omanensis, a Deep-Sea Shark under the Stress of Fisheries
in the Gulf of Aqaba (Northern Red Sea)
Baranes, A. .......................................................................................................................88
Cartilaginous Fishes of the Mediterranean Coast of Israel
Golani, D...........................................................................................................................95
Elasmobranch Research in Slovenia: State of the Art
Mavrič, B., Turk, R., Lipej, L........................................................................................ 101
The Gulf Of Gabès: A Spot for the Mediterranean Elasmobranchs
Bradaï, M. N., Saidï, B., Enajjar, S., Bouain, A. ...........................................................107
The MEDLEM Database Application: A Tool for Storing and
Sharing the Large Shark’s Data Collected in the Mediterranean Countries
Serena, F., Barone, M., Mancusi, C., Magnelli, G., Vacchi, M. ..................................118
Status of the Sharks in the Adriatic
Soldo, A.............................................................................................................................128
Use of Scientific Campaigns (Trawl Surveys) for the Knowledge of the
Sensitive Habitats. A Review of the MEDITS, GRUND and APHIA Data
with Special Attention to the Italian Seas
Serena, F., Relini, G.........................................................................................................135
By-Catch of Sharks in the Mediterranean Sea: Available Mitigation Tools
Ferretti, F., Myers, R. A. .................................................................................................149
Chondrichthyes in Cyprus
Hadjichristophorou, M....................................................................................................162
A Summary of Shark By-Catch in the Italian Pelagic Fishery
Garibaldi, F. .....................................................................................................................169
Shark Research Programme in Libya
Seret, B., Ben Abdallah, A. .............................................................................................176
Conservation Management of Sharks and Rays (Vertebrata:
Chondrichthyes) in the Maltese Islands (Central Mediterranean)A Review of Status and Trends
Schembri, T. .....................................................................................................................177
Page
General Overview of Sharks Landing and Research Programme
in Morocco
Moumni, A., Mesfioui, A., Semmoumy, S.......................................................................188
Establishing an Informative (Sampling) Network for the Assessment
of the Stock Status of Sharks: A Review
Macías, D., Melendez, M. H. ............................................................................................194
Shark Exploitation and Conservation in Syria
Saad, A., Ali, M., Seret, B.................................................................................................202
Fishing and Cartilaginous Fishes on Adriatic and Ionian
Seas of Albania
Arapi, D., Sadikaj, R., Nelaj, E........................................................................................209
Annex I ...............................................................................................................................215
Conclusions and Technical Advice
Annex II..............................................................................................................................219
Draft protocols proposed by RAC/SPA for monitoring commercial landings
and discards by species, as well as for recording data on rarely observed,
endangered and protected species
Annex III ............................................................................................................................259
List of Participants
PREFACE
The International Workshop on Mediterranean Cartilaginous Fish with Emphasis on
Southern and Eastern Mediterranean was held in Ataköy Marina, Istanbul, Turkey on
15-16 October 2005. The previous day, 14 October, was dedicated to deepen in the
Turkish national component of the same subject, gathering the national experts on the
matter. It was a meeting organized by Turkish Marine Research Foundation (TÜDAV)
with RAC/SPA support, within the framework of the Action Plan for the Conservation
of Cartilaginous Fishes (Chondrichthyans) in the Mediterranean Sea (UNEP-MAPRAC/SPA). This was the first meeting ever intended to understand the problems on
conservation and fisheries management of cartilaginous fish in the Southern and Eastern
Mediterranean.
The aim of the workshop was to exchange information among scientists and
experts especially in the developing Mediterranean countries. This meeting focused on
by-catch and discard as a serious threat on the cartilaginous fish and their stocks,
information retrieval for standard protocols and a database to be used in the whole
Mediterranean region, critical habitats such as nursery areas, collaboration and
coordination among all the countries along the Mediterranean.
We hope that the results of this workshop will help better understand the
cartilaginous fish species in the Mediterranean Sea for their protection.
We thank Ataköy Marina for kindly hosting the meeting. Also our special
thanks are due to Dr. E. Mümtaz TİRAŞİN for his valuable comments on the drafts of
the proceedings as well as to the Ministry of Environment and Forestry for their
support.
Daniel CEBRIAN
Programme Officer
UNEP-MAP
Regional Activity Centre for
Specially Protected Areas (RAC/SPA)
Bayram ÖZTÜRK
Director
Turkish Marine Research Foundation
I
Proc. of the Int. Workshop on Med. Cartilaginous Fish with Emphasis on South.- East. Med., 14-16 Oct. 06, Istanbul-Turkey
POPULATION PARAMETERS OF SPINY DOGFISH, Squalus acanthias
FROM THE TURKISH BLACK SEA COAST AND ITS COMMERCIAL
EXPLOITATION IN TURKEY
Ertuğ DÜZGÜNEŞ1, İbrahim OKUMUŞ1, Muzaffer FEYZİOĞLU1 and Nüket SİVRİ2
1
2
K.T.U. Faculty of Marine Sciences, Dept. of Fisheries, 61530 Camburnu/ Trabzon, Turkey
University of Istanbul, Faculty of Engineering, Dep. of Env. Eng, 34320 Avcılar/Istanbul, Turkey
Abstract
Spiny dogfish Squalus acanthias is one of the most widespread shark species in the
world’s oceans. It is also the only shark species inhabiting the brackish water of the
Black Sea. The Black Sea stock is not commercially exploited and studies on this
species are rare. In this preliminary study, we aimed to examine the population structure
along the south-eastern Black Sea coast of Turkey. A total of 267 (85 male and 182
female) specimens were collected and size (length and weight) distribution, sex ratio,
gutted weight, liver weight and weight of dorsal fin as edible body parts, and the
relationships between various parameters were determined. Size in length and weight
varied between 36.5 and 141.5 cm, and 135 and 16140 g. The mean (±se) length and
weight were 88.25±2.157 cm and 3319±204 g for males, and 92.55±1.73 cm and
4387±217.6 g for females. Sex ratio was estimated as 68 % females and 32 % males.
The length-weight relationship for the stock was derived as W=0.009*L3.3423 (r2=
0.9607). Mean gutted body, liver and first dorsal fin weights were 1888±317.1,
605.87±129.5 and 117±44.8 g, respectively.
Total landings of spiny dogfish peaked in 1974 at 11,126 metric tonnes,
followed by fluctuations during the 1980s and continued to decline after early 1990s.
The vast majority (70 %-98 %) of the catch comes from the Black Sea. Spiny dogfish
are caught primarily with trawls, gill nets and purse seines as by-catch. Spiny dogfish
has been exported as fresh/chilled into Greece, Italy, Norway and Spain. This species is
used in the popular “fish and chips” meals as well as marketed for its oil and as fish
meal.
Key words: Spiny dogfish, Black Sea, population parameters, landings.
Introduction
The spiny dogfish Squalus acanthias is abundant throughout the north temperate waters
of the Pacific and Atlantic Oceans, the Mediterranean Sea, the Aegean Sea and the
Black Sea. The species is found in cold and warm temperate oceans at temperatures
between 6 and 30°C. It is tolerant to a wide range of salinities and can be found in
brackish waters like the Black Sea, however, it prefers full-strength seawater and does
not enter freshwater habitats. Spiny dogfish occur epibenthically, however they move
1
through the water column, up to surface water. They are found in inshore and offshore
waters over the continental shelf to depths of 900 m (URL-1; 2).
Annual catch in Turkey was around 2115 t (0.4 % of total marine fishes
production) (FILIZ and TOGULGA, 2002) and limited with by-catch. Thus few studies
of growth and meat yield have been conducted in the surrounding seas of Turkey. The
main aim of this paper is to present the results of a study on stock structure of the spiny
dogfish conducted in the north-eastern part of the Black Sea. In addition commercial
exploitation of the species is also evaluated.
Materials and Methods
Between November 1994 and March 1995, 267 specimens of dogfish were collected
from by-catches of commercial purse seine and gill net fishing along the North-eastern
Black Sea coast of Turkey (Fig. 1). Total length (TL) and fork length (FL) were taken
according to COMPAGNO (1984). Body weight (TW), gutted, liver and dorsal fins
were measured to nearest 1 g.
Figure 1. Sampling area
Weight–length relationships were estimated by fitting an exponential curve,
W = aLb, to the data (RICKER, 1973; 1975). Parameters a and b of the exponential
curve were estimated by linear regression analysis over log-transformed data (log W =
log a + b log L), where W is the total weight (g), L the total length (cm), a the intercept
and b the slope. Although a only corresponds to a condition factor when b (the
allometry coefficient) equals 3, different authors refer to a as the relative condition
factor (ANDERSON and GUTREUTER, 1983) or the allometric condition factor
2
(RICKER, 1975) when b ≠ 3. The parameter a is then used as a proxy of the condition
factor. The degree of association between the variables W and L (or log W and log L)
was evaluated by the coefficient of determination (r2).
Percentage ratio of liver weight, total weight, gutted weight and first dorsal fin
to total body weight were calculated, and sex ratio was estimated.
The catch statistics gathered and published by State Statistics Institute (SSI,
1971-2004) are used, while export figures obtained both from the SSI and the Under
Secretariat of Foreign Trade.
Results and Discussion
The sample was composed of 85 males (32 %) and 182 (68 %) females. The average
size of the spiny dogfish was 91.18±1.368 (35.3-141.5 cm) with males ranging from
36.5-114 cm and females from 35.3-141.5 cm in length (Table 1). Just over 25% of the
specimen fall in size range 95-105 cm (Fig. 2). Females reach mean weight of
4.387±217.6 kg, with a maximum recorded weight of 16.140 kg, while mean and
maximum weights for males were 3.318±204.1 and 6.6 kg, respectively. Females attain
a greater size than males (P<0.05) (Table 1).
Table 1. Total length, fork length and total weight (mean, standard deviation, range) of
spiny dogfish caught in the south-eastern Black Sea coast
Variables
N
Mean±s.e.
N
Female
N
Male
Total length
(cm)
267
91.18±1.368
(35.3-141.5)
182
92.56±1.730
(35.3-141.5)
85
88.25±2.157
(36.5-114)
Fork length (cm)
267
82.43±1.269
182
83.97±1589
85
79.14±2.043
Total weight (g)
267
4047±164.1
(135-16410)
182
4387±217.6
(135-16140)
85
3318±204.1
(195-6600)
0,30
Frequency %
0,25
TOTAL
FEMALES
0,20
MALES
0,15
0,10
0,05
0,00
35-45
45-55
55-65
65-75
75-85
85-95
95-105
105-115
115-125
125-135
135-145
Length (cm)
Figure 2. Length - frequency distribution of spiny dogfish specimens sampled from the
South-eastern Black Sea
3
The relationships of length (TL) to weight (BW) were derived as: WA =
0.0009*L3.3423 (r=0.9802, N=276) for both sexes combined, WF = 0.0014*L3.542
(r=0.9607, N=182) for females and WM = 0.001*L3.3148 (r=0.9898, N=85) for males
(Fig. 3).
7000
Males
3,3148
W = 0.001L
6000
2
r = 0.9797
Weight (g)
5000
4000
3000
2000
1000
0
30
50
70
90
110
130
Length (cm)
16000
Females
3.2542
W = 0.0014 L
14000
2
r = 0.9623
Weight (g)
12000
10000
8000
6000
4000
2000
0
30
50
70
90
110
130
150
Length (cm)
18000
All
16000
W = 0.0009*L3.3423
14000
r2 = 0.9607
Weight (g)
12000
10000
8000
6000
4000
2000
0
30
50
70
90
110
130
150
Length (cm)
Figure 3. Length – weight relationships for all specimens, males and females.
4
In addition highly significant linear relationship was observed between
measures total and fork length values: FL = 0.9194*TL – 1.1347 (r = 0.9882).
Females outnumbered (68 % versus 32 %) males in the current. The similar
results were reported by SAMSUN et al. (1995). SHEPHERD et al. (2002) reported that
in the Bay of Fundy and Scotian Shelf, Canada, dogfish sex was affected by habitat
associations. Males were found to occupy bottom water of significantly higher salinities
and depths than that occupied by females. Length also significantly affected habitat
associations. Smaller dogfish occupied relatively deep, high salinity bottom water
compared with larger dogfish. This fact may also valid for the vertical distribution of
spiny dogfish in the Black Sea.
Size range of specimens was similar to that reported by SAMSUN et al. (1995)
earlier in the Black Sea. However, mean total length values were higher than those
found in above mentioned study. Mean weight of females is very similar to that
determined by SAMSUN et al. (1995). Average length of the Black Sea dogfish is much
higher than that of the Northern Aegean Sea population according to figures (male:
47.81±2.87; 38.5 – 56.5 cm and female: 59.47±6.03; 27.0 – 70.5 cm) given in FILIZ
and MATER (2002). Elsewhere in the world SHEPHERD et al. (2002) reported the
average weight of female and male dogfish as 1.36 and 1.42 kg respectively, while the
mean total length values were 66.0 cm for females and 69.9 cm for males in the Bay of
Fundy and Scotian Shelf, Canada. SAUNDERS and MCFARLANE (1993) estimated
size range of females as 40 – 122 cm in the Strait of Georgia, British Columbia. This
limited comparison indicates that the current Black Sea spiny dogfish population attain
higher sizes than both that of other Turkish seas and those in other parts of the world.
The main reasons may be the commercial exploitation rate (almost none in the Black
Sea, except for bycatch) and environmental factors.
The length-weight relationship parameters of spiny dogfish from the Southeastern Black Sea are similar to the estimates given by SAMSUN et al. (1995) for the
central Black Sea (a = 0.0022, b = 3.1413), KUTAYGIL and BILECIK (1998) for
South-western Black Sea (a= 0.027, b=3.02), FILIZ and MATER (2002) for the
Northern Aegean population (a = 0.0031, b = 3.1056). However there seems to be
differences regarding the a and b values between the current study and earlier studies in
the same area by AVSAR (1996; 2001), who estimated these values as a= 0.0040 and b
= 2.95. According to the author this was due to due to differences in sampling times.
Similar findings have also been reported in other parts of the world, for example;
JONES and GEEN (1977) for the Strait of Georgia, British Columbia (a= 0.0017 and b=
3.47).
Some organ weights and ratios from dissected samples, namely liver, internal
organs, first dorsal fin and gutted weights are presented in Table 2. Liver weight
consisted of 14.39 % total weight and did not differ between sexes, while gutted and
internal organ weights as percentage of total weight showed significant differences
between sexes, former in favour of males and later females. The mean first dorsal fin
weight consisted of 4.12 % and 4.46 % of total weights of females and males,
respectively.
5
Table 2. Some organ weights and ratios from dissected samples (LW: Liver weight (g),
TW: Total weight (g), VW: viscera weight (g), DFW: dorsal fin weight (g),
GW: gutted weight (g)).
LW
GW
1st
DFW
VW LW/TW GW/TW LW/VW DFW/TW VW/TW WI/GW DFW/GW
%
%
%
%
%
%
%
Parameters
ALL
Mean
606
1888
117
1241
14.39
66.52
44.11
4.25
33.45
54.60
6.41
N
51
47
47
47
51
47
47
47
47
47
47
10
90
5
35
6.65
32.73
14.49
1.14
19.63
24.42
2.02
Max
Min
3670 8970
2115
7170
34.92
80.37
89.19
23.20
67.27
55.6
32.74
SE
129.5 317.1
44.8
243.8
0.882
1.447
2.207
0.570
1.450
4.534
0.861
2318
155
1622
14.56
42.86
4.12
34.36
55.88
6.33
FEMALE
Mean
767
65.64
N
32
29
29
29
32
29
29
29
29
29
29
Min
10
100
5
35
6.65
43.20
14.49
1.14
19.63
24.42
2.02
Max
3670 8970
2115
7170
33.99
80.37
81.56
19.28
56.80
31.48
32.74
SE
190.9 475.0
71.9
367.3
1.107
1.815
2.642
0.612
1.815
4.627
1.046
MALE
Mean
334
1196
56
627
14.11
67.93
46.13
4.46
31.97
52.55
6.54
N
19
18
18
18
19
18
18
18
18
18
18
15
90
5
45
7.14
32.73
17.30
1.48
21.30
27.06
2.41
Max
Min
1980 3450
210
2220
34.92
78.70
89.19
23.20
67.27
55.6
31.11
SE
113.1 257.2
11.9
161.6
1.494
2.421
3.939
1.138
2.430
9.382
1.528
Commercial Exploitation in Turkey
The spiny dogfish is not a major commercial species, but it has been caught as
by-catch by purse seines used for pelagic fishes like anchovies, sardines and horse
mackerels. There is no domestic consumption and all the meat and fins are exported.
Maximum catch was 11,126 tons in 1979 and 98 % of the total was obtained from the
Black Sea (Fig. 4). 97 % had been caught from the Eastern Black Sea. The abundance
of the dogfish has also showed similar fluctuations as commercial fish species, mainly
pelagics which were heavily affected by overfishing and invasive Ctenophora species
Mnemiopsis leidyi during 199s (Fig. 5). The recent production has occured around 650
metric tons for Turkey, and 430 metric tons for the Black Sea (Fig. 4). According to the
latest catch data the share of the Black Sea and Eastern Black Sea has decreased to 67 %
and 62 %, respectively (Fig. 4).
Dogfish are exported to some Mediterranean countries, namely Greece, Italy
and Spain as fresh/chilled product (Table 3; 4).
6
2003
1979
20; 0%
10; 0%
60; 9%
85; 13%
208; 2%
150; 1%
400;
63%
71; 11%
29; 4%
EASTERN BLACK SEA
WESTERN BLACK SEA
AEGEAN SEA
SEA OF MARMARA
MEDİTERRANEAN
10738; 97%
Figure 4. Changes of the share of dogfish catch among regions from 1979 to 2003 (SSI).
35000
30000
TOTAL CATCH(tons)
25000
20000
15000
10000
5000
0
1970
1975
EASTERN BLACK SEA
1980
WESTERN BLACK SEA
1985
BLACK SEA TOTAL
1990
AEGEAN SEA
1995
SEA OF MARMARA
2000
MEDİTERRANEAN
Figure 5. Additive area chart of dogfish catch by years.
7
TURKEY TOTAL
Table 3. Export quantities and values (US $) of dogfish from Turkey (All species)
(Under secretariat of Foreign Trade, 2005)
2000
2001
Country
kg
$
France
1851
5054
8
25
Netherlands
2002
2003
2004
kg
$
kg
$
kg
$
kg
$
540
1340
Italy
35498
98218
4790
19440
3646
7924
16030
66079
1589
9688
Greece
65434
189231
144677
387641
124670
350251
32811
125037
60069
281243
8327
9901
69985
300.832
Germany
Spain
Norway
10360
60770
Austria
20
81
5690
35123
Bulgaria
Canada
Hong Kong
Istanbul Free
Zones
Total
1220
7232
10
50
114941
362.001
19
70
155176
442.274
128316
358.175
1465
696
50306
191.812
Table 4. Export of spiny dogfish as fresh/chilled from Turkey (Under secretariat of
Foreign Trade, 2005)
Years
kg
$
Years
kg
$
Years
kg
$
1996
607
2171
1999
100
332
2002
25161
62177
1997
3691
8826
2000
540
1949
2003
7717
26159
1998
1025
2484
2001
2017
2004
4936
23218
References
ANDERSON, R., GUTREUTER, S., 1983. Length, weight and associated structural
indices. In: NIELSEN, L., JOHNSON, D., (Eds). Fisheries Techniques. American
Fisheries Society, Bethesda, MD, pp 283–300.
AVSAR, D., 1996. Sex, Age and Growth of the Spurdog (Squalus acanthias, L., 1758)
in the Southeastern Black Sea. Yugoslav Journal of Operations Research 6 (2), 295304.
AVSAR, D., 2001. Age, Growth, Reproduction and Feeding of the Spurdog (Squalus
acanthias Linnaeus, 1758) in the South-eastern Black Sea. Estuarine, Coastal and
Shelf Science 52, 269-278.
8
COMPAGNO, L. J. V., 1984. Sharks of the world: An annotated and illustrated
catalogue of sharks species known to date. FAO Fisheries Synopsis Nº 125, 4 (1 and
2), pp 655.
FILIZ, H., MATER, S., 2002. A preliminary study on length-weight relationships for
seven elasmobranch species from North Aegean Sea, Turkey. E.U. Journal of
Fisheries and Aquatic Sciences 19 (3-4), 401 – 409.
FILIZ, H., TOGULGA, M., 2002. Commercial Elasmobranch Species in Turkey’s
waters, their Fisheries and Management (in Turkish). In: ÖZHAN, E., ALPASLAN,
N. (eds), Türkiye’nin Kıyı ve Deniz Alanları IV. Ulusal Konferansı Bildiriler Kitabı,
Cilt 2, 5-8 Kasım 2002, İzmir, Türkiye, pp 717-727.
JONES, B. C., GEEN, G. H., 1977. Age and growth of spiny dogfish (Squalus
acanthias) in the Strait of Georgia, British Columbia. Research and Development
Technical Report. Fisheries and Marine Service, No. 699, pp 16.
KUTAYGIL, N., BILECIK, N., 1998. Studies on a shark species, picked dogfish
(Squalus acanthias L.) distributed along the Anatolian littoral zones in the Black Sea.
Ministry of Agriculture and Rural Affairs, Fisheries Enst. Publ. No. 2, Bodrum, pp 71
(in Turkish).
RICKER, W. E., 1973. Linear regressions in fishery research. J. Fish. Res. Board of
Can. 30, 409 -434.
RICKER, W. E., 1975. Computing and interpretation of biological statistics of fish
populations. Bull. of J. Fish. Res. Board of Can.191, 382 p.
SAMSUN, O., POLAT, N., GÜMÜŞ, A., 1995. Length-weight relationship of spiny
dogfish (Squalus acanthias L., 1758) caught in the central Black Sea region of
Turkey. E.Ü. Su Ürünleri Dergisi 12 (1-2), 27-35 (in Turkish).
SAUNDERS, M. W., McFARLANE, G. A., 1993. Age and length-at-maturity of the
female spiny dogfish, Squalus acanthias, in the Strait of Georgia, British Columbia.
Canada. Environmental Biology of Fishes 38, 49-57.
SHEPHERD, T., PAGE, F., MACDONALD, B., 2002. Length and sex-specific
associations between spiny dogfish (Squalus acanthias) and hydrographic variables in
the Bay of Fundy and Scotian Shelf. Fisheries Oceanography 11 (2), 78-89.
STATE STATISTICS INSTITUTE (SSI), 1971-2004. Fisheries Statistics. Prime
Ministry’s Office, Ankara.
UNDER SECRETARIAT OF FOREIGN TRADE, 2005. Export data for fresh/chilled
dogfish (unpublished).
URL-1,2005.http://new-brunswick.net/new-brunswick/sharks/species/spinydogfish.html
URL-2,2005.http://www.flmnh.ufl.edu/fish/Gallery/Descript/SpinyDogfish
9
Proc. of the Int. Workshop on Med. Cartilaginous Fish with Emphasis on South.- East. Med., 14-16 Oct. 06, Istanbul-Turkey
SEASONAL VARIATION OF Hysterothylacium aduncum INFECTION IN
THE COMMON GUITARFISH, Rhinobatos rhinobatos IN ISKENDERUN
BAY (NORTH-EASTHERN MEDITERRANEAN SEA) TURKEY
Ercument GENÇ1, Yasemin B. YILDIRIM1, Nuri BAŞUSTA2 and Mustafa ÇEKİÇ3
1
Programme of Fish Diseases, Faculty of Fisheries and Aquaculture, Mustafa Kemal University, Tayfur
Sokmen Campus 31034, Antakya/ Hatay, Turkey. E-mail: ercumentgenc@yahoo.com
2
ATA Aquaculture and Fisheries Research Centre, Harran University, Sanliurfa, Turkey
3
Cukurova Unıversity, Yumurtalik Vocatinal School, 01680,Yumurtalik/Adana, Turkey
Abstract
A total of 244 individuals of the common guitarfish, Rhinobatos rhinobatos (TL range:
31-144 cm), were obtained between March 2003 and February 2005 from commercial
fishing vessels in Iskenderun Bay, North-eastern Mediterranean Sea, Turkey and
examined for the presence of an anisakid nematode Hysterothylacium aduncum
(Rudolphi) in the digestive tract. The parasites (fourth-stage larvae, L4s) were found in
spiral valve (Infected samples, Ni: 88, TLi range: 31-127 cm) of common guitarfish.
Seasonal H. aduncum intensity (MI: mean±SD) and prevalence (P: %) values were
determined. Throughout the research, the highest MI and P values were found in MayJune 2004 (7.67±2.16 %) and March-April 2003 (78.57 %). The lowest MI and P values
were found in March-April 2003 (3.91±1.97) and November-December 2003 (7.69 %),
respectively. During the research period, seasonal changes of MI, P, and A (abundance:
mean±SD) values were given in detail.
Key words: Mediterranean Sea, Rhinobatos rhinobatos, parasites, nematoda,
Hysterothylacium aduncum.
Introduction
Within the marine ecosystem, elasmobranchs play an important role at or near the top of
the food web (ABELLA and SERENA, 2005). The elasmobranch species are among the
most studied fish (KNOFF et al., 2001; HENDERSON et al., 2002; KLIMPEL et al.,
2003). It is known that the top of the food web’s species (predator fish) serve as
intermediate and paratenic hosts for parasitic diseases. However, despite the large
volume of biological information available for the elasmobranchs (HENDERSON et al.,
2002) dedicated parasitology studies including common guitarfish are very few
especially in the Mediterranean Sea. In Turkey, guitarfish are readily sold in markets as
food for human consumption. It is critically important for sustainable fisheries and
aquaculture activities and human health to have reliable information about potentially
10
pathogenic organisms that may be present in their region. Helminth infections are
seriously taken to consideration for cultured (BERLAND, 1987; SUNDERS, 2003) and
wild marine fish (GENC, 2002). Nematodes are one of the most important agents for
financial losses in marketing value of fishes. The nematode problem is known as
anisakidosis (ABOLLO et al., 2001).
Transmission of species of Anisakidae family is dependent upon water and
usually involves aquatic invertebrates and fish as intermediate or paratenic hosts. The
species of Hysterothylacium in the adult stage are normally found in the guts of fishes
(ANDERSON, 2000). They are cosmopolitan and non zoonotical anisakid species
(CARVAJAL et al., 1995; GONZALEZ, 1998). Although, WILLIAMS and JONES
(1976) document cases of human infection (eosinophilic granulomata) by larvae of H.
aduncum.
According to SÁNCHEZ (1998), the adults are found in the alimentary canal
of marine teleosts and, occasionally, in the stomach; several marine invertebrates act as
intermediate hosts. Third-stage larvae have been found encapsulated in the mesentery
and viscera of a wide range of fish that act as transport hosts (BERLAND, 1961;
PETTER and MAILLARD, 1988; KØIE, 1993). H. aduncum is usually found in
inshore, benthic hosts. This parasite probably only occurs in offshore fishes that acquire
them from eating inshore fishes. In Europe it is the most common larval roundworm
encysted in inshore fishes, occurring in almost every fish in some areas (WILLIAMS
and BUNKLEY-WILLIAMS, 1996). In the literature, larvae and adults have frequently
been refereed to Contracaecum and Tynascaris but DEARDORFF and OVERSTREET
(1980) have distinguished Hysterothylacium and Contracaecum.
Previous research pointed out H. aduncum infection all around the world
including the Mediterranean Sea (ANDERSON, 2000; HENDERSON et al., 2002;
FERNÁNDEZ et al., 2005; MARQUES et al., 2005). Furthermore, anisakid infections
were reported in several fish, except chondrichthyans in the Iskenderun Bay (the northeast Mediterranean Sea). This study was designed to investigate the condition of
common guitarfish as a representative of chondrichthyans with regards to H. aduncum
infections in the Iskenderun Bay, Turkey.
Materials and Methods
A total of 244 individuals of the common guitarfish, R. rhinobatos were caught during
the period from March 2003 to February 2005 in an area of the North-eastern
Mediterranean Sea (Iskenderun Bay) located at 35°54'09''E-36°30'05''N, 35°54'09''E36°25'04''N (Fig. 1). Total length of each fish was measured. After the abdominal
dissection, internal organs especially intestinal tract was directly examined for the
presence of parasitic nematode H. aduncum. When encountered for each specimen the
nematode were counted and identified according to their morphologic features using a
light microscope (DEARDORFF and OVERSTREET, 1980; KØIE, 1993; BERLAND,
1998; ANDERSON, 2000). The prevalence (P), the mean intensity (MI) and the
abundance (A) of H. aduncum were calculated as defined by BUSH et al. (1997).
11
Figure 1. Sampling area.
Results
Common guitarfish R. rhinobatos specimens examined for anisakid nematodes ranged
in length from 31 to 144 cm. Only one internal parasite species was found in spiral
valves of fish and identified as Hysterothylacium aduncum (Rudolphi). Number of H.
aduncum worms (fourth-stage larvae, L4s) per fish was ranged in 1-12. The overall
Prevalence (P), mean intensity (MI) and mean abundance (A) are listed in Table 1.
Table 1. Sample of common guitarfish examined for anisakid, H. aduncum.
Sample size (N), Total body length (TL: mean± SD; range), Infected samples (Ni), Total body length of
infected fish (TLi: mean±SD; range), Total number of nematode (Nn) Prevalence (P: %), Mean intensity (MI:
mean± SD), Abundance (A: mean± SD), Not detected (ND)
12
The data showed seasonal variations with the highest prevalence in spring
seasons (Fig. 2). There was a positive relationship between warm seasons and the
prevalence values of nematodes in the common guitarfish. Seasonal changes of basic
parameters were found as follows; P values were Spring> Summer> Fall> Winter, MI
values were Fall> Winter> Summer> Spring and, A values were Spring> Fall>
Summer> Winter.
90
14
2003-2005
80
12
70
P%
50
8
40
6
30
M I, A
10
60
4
20
2
10
0
0
Jan.- Feb.
Prevalence (P: %)
March- Apr.
May- June
July- Aug.
Mean intensity (MI: mean±SD)
Sept.- Oct.
Nov.- Dec.
Abundance (A: mean±SD)
Figure 2. Seasonal changes of parasitic nematodes.
Discussion
Anisakinea are parasites mainly infesting the marine mammals, turtles, piscivorous
birds and elasmobranches (ANDERSON, 2000). Anisakidae characteristically occur in
deep waters in meso- or benthopelagic species and are typically found in predators.
Natural transmission also occurs in specific habitats and in relation to characteristic host
diets (CANNON, 1977; ABOLLO et al., 2001; ÁLVAREZ et al., 2002). According to a
previous study on teleosts helminth parasites, Hysterothylacium sp. was found in sparid
fish (Sparidae) with 1.74% prevalence level (GENC, 2002). In the present study, we
only detected the same Anisakidae, H. aduncum in R. rhinobatos. This is not surprising
considering the same sampling area. ABOLLO et al. (2001) note that in temperate
waters, anisakid parasites are a natural part of the trophic web of marine ecosystems.
Furthermore, many authors claimed that H. aduncum is not very host-specific in either
its adult stage or its larval stages. Many parasites, especially helminthes, possess
complex life cycles involving trophic transmission from one host to the next by
consumption of infected intermediate hosts (CANNON, 1977; ANDERSON, 2000;
ABOLLO et al., 2001; ÁLVAREZ et al., 2002). SMITH (1983) reported that
seasonality might not be expected because anisakids eggs are shed by the final hosts,
possibly throughout the year, and they may develop and hatch at any time.
13
AMUNDSEN et al. (2003) indicated that parasite carrying capacity might be higher in
predator hosts. Beside that, more than 100 species of invertebrates in seven phyla have
been reported as intermediate hosts. This wide range of hosts may help to explain the
great abundance and broad distribution of Hysterothylacium aduncum (WILLIAMS and
BUNKLEY-WILLIAMS, 1996). Since the common guitarfish is a predator, the
prevalence of infestations in elasmobranchs is worth being taken into account. These
prevalence’s were consistent with AMUNDSEN et al. (2003)’s notion, excluding of the
prevalence’s of nematode infections in wild fish.
Results of the present study indicated that highest MI and P values were found
in May-June 2004 (7.67±2.16 %) and March-April 2003 (78.57 %). The lowest MI and
P values were found in March-April 2003 (3.91±1.97) and November-December 2003
(7.69%). In conclusion, the present study is the first report on the presence of anisakid
nematodes in the common guitarfish, R. rhinobatos in Iskenderun Bay. Since H.
aduncum could be a serious threat to common guitarfish. Future studies are planed to
determine the transmission pathways molecular biology methods.
Acknowledgements
The authors would like to acknowledge the support provided by the commercial
fishermen at Samandag and Iskenderun (Hatay) Fisheries Cooperative Society
throughout this research. We also wish to thank Dr.Bernard SERET and Dr. Fabrizio
SERENA for their scientific comments and advice. This work was supported in part by
grant from the Scientific Research Foundation of Mustafa Kemal University, Antakya,
Hatay, Turkey.
References
ABELLA, A. J., SERENA, F., 2005. Comparison of elasmobranch catches from
research trawl surveys and commercial landings at port of Viareggio, Italy, in the last
decade. e- J. Northwest Atlantic Fish. Sci. (Upload date: 14 Feb 05) 35, 23.
ABOLLO, E., GESTAL, C., PASCUAL, S., 2001. Anisakis infestation in marine fish
and cephalopods from Galician waters: an updated perspective. Parasitol. Res. 87(6),
492-9.
ÁLVAREZ, F., IGLESIAS, R., PARAMÁ, A. I., LEIRO, J., SANMARTIN, M., 2002.
Abdominal macroparasites of commercially important flatfishes (Teleostei:
Scophthalmidae, Pleuronectidae, Soleidae) in northwest Spain (ICES IXa).
Aquaculture 213, 31-53.
AMUNDSEN, P. A., KNUDSEN, R., KURIS, A. M., KRISTOFFERSEN, R., 2003.
Seasonal and ontogenetic dynamics in trophic transmission of parasites. Oikos 102,
285-293.
ANDERSON, R. C., 2000. Nematode parasites of vertebrates: their development and
transmission. CABI Publishing, CAB International, Wallingford, Oxon, UK.
BERLAND, B., 1961. Nematodes from some Norwegian marine fishes. Sarsia 2, 1-50.
14
BERLAND, B., 1987. Helminth problems in sea-water aquaculture. In: Stenmark E,
Malmberg G (eds) Parasites and diseases in natural waters and aquaculture in Nordic
countries., Zoo-tax, Naturhistoriska riksmuseet, Stockholm, Sweden, pp 56-62.
BERLAND, B., 1998. Biology of Hysterothylacium species (S-K2-3). global aspects of
Anisakidosis (E-2). Symposium (E), Parasitol. Int. (Suppl.) 47, 23-48.
BUSH, A. O., LAFERTY, K. D, LOTZ J. M., SHOSTAK, A. W., 1997. Parasitology
meets ecology on its own terms: Margolis et al. revisited. J. Parasitol. 83, 575-583.
CANNON, L. R. G., 1977. Some ecological relationships of larval ascaridoids from
southeastern Queensland marine fishes. Int. J. Parasitol. 7, 227– 232.
CARVAJAL, J., GONZALEZ, L., TOLEDO, G., 1995. New record of
Hysterothylacium aduncum (Nematoda: Anisakidae) in salmonids cultured in sea
farms from southern Chile. Res. Rev. Parasitol. 55, 195-197.
DEARDORFF, T. L., OVERSTREET, R. M., 1980. Contracaecum multipapillatum (=
C. robustum) from fishes and birds in the northern Gulf of Mexico. J. Parasitol. 66,
853–856.
FERNÁNDEZ, M., AZNAR, F.J., MONTERO, F.E., RAGA, J.A., 2005. Endoparasites
of the blue whiting, Micromesistius poutassou from north-west Spain. J. Helminthol.
79, 1(7), 15-21.
GENC, E., 2002. The Endoparasites and histopathologies found in the some commercial
teleosts in the Bay of Iskenderun, Turkey. PhD thesis, Aquaculture and fisheries
programme, Institute of Natural and Applied Sciences University of Cukurova,
Adana, Turkey.
GONZALEZ, L., 1998. The life cycle of Hysterotylacium aduncum (Nematoda:
Anisakidae) in Chilean marine farms. Aquaculture 162, 170–185.
HENDERSON, A. C., FLANNERY K., DUNNE J., 2002. An investigation into the
metazoan parasites of the spiny dogfish (Squalus acanthias L.), off the west coast of
Ireland. J. Nat. History 36 (14), 1747-1760.
KLIMPEL, S., PALM, H. W., SEEHAGEN, A., 2003. Metazoan parasites and food
composition of juvenile Etmopterus spinax (L.,1758) (Dalatiidae, Squaliformes) from
the Norwegian Deep. Parasitol. Res. 89 (4), 245-251.
KNOFF, M., DE SAO CLEMENTE, S.C., PINTO, R.M., GOMES, D.C., 2001.
Nematodes of elasmobranch fishes from the southern coast of Brazil. Mem. Inst.
Oswaldo Cruz. Jan: 96 (1), 81-87.
KØIE, M., 1993. Aspects of the morphology and life cycle of Hysterothylacium
aduncum (Rudolphi 1802) (Nematoda, Ascaridoidea, Anisakidae). Can. J. Zool. 71,
1289-1296.
MARQUES, J. F., SANTOS, M. J., COSTA, J. L., COSTA, M. J., CABRAL, H.
N., 2005. Metazoan parasites as biological indicators of population structure of
Halobatrachus didactylus on the Portuguese coast. J. Appl. Ichthyol. 21 (3), 220–224.
PETTER, A. J., MAILLARD, C., 1988. Larves d'Ascarides parasites de poisons en
Mediterranee occidentale. Bull. Mus. Natl. Hist. Nat. Paris 10, 347-369.
SÁNCHEZ, J. M., PANIAGUA, I., VALERO, A., 1998. Contribution to the knowledge
of Hysterothylacium aduncum through electrophoresis of the enzymes glucose
phosphate isomerase and phosphoglucomutase. Parasitol. Res. 84 (2), 160-163.
15
SMITH, J. W., 1983. Anisakis simplex (Rudolphi 1809, det. Krabbe 1878) (Nematoda:
Ascaridoidea): morphology and morphometry of larvae from euphasiids and fish, and
a review of the life-history and ecology. J. Helminthol. 57, 205-224.
SUNDERS, G. A., 2003. Cestodes in Atlantic salmon (Salmo salar L.) at a w
Norwegian hatchery: infection dynamics, aspects of development and pathology.
Candidatus Scientiarum Thesis, Department of Fisheries and Marine Biology,
University of Bergen, Norway.
WILLIAMS, E. H., JR., BUNKLEY-WILLIAMS, L., 1996. Parasites of off shore, big
game sport fishes of Puerto Rico and the Western North Atlantic. Puerto Rico
Department of Natural and Environmental Resources, San Juan, Puerto Rico, and
Department of Biology, University of Puerto Rico, Mayaguez, Puerto Rico, pp 384.
WILLIAMS, H. H., JONES, A., 1976. Marine helminths and human health.
Commonwealth Institute of Helminthology Misc. Publication No 3, pp 47.
16
Proc. of the Int. Workshop on Med. Cartilaginous Fish with Emphasis on South.- East. Med., 14-16 Oct. 06, Istanbul-Turkey
SOME BIOLOGICAL ASPECTS OF THE LESSER SPOTTED
DOGFISH Scyliorhinus canicula (Linnaeus, 1758) IN EDREMIT BAY
(THE NORTHERN AEGEAN SEA) TURKEY
Dilek TÜRKER ÇAKIR, Hatice TORCU KOÇ and Zeliha ERDOĞAN
Balikesir University, Faculty of Science and Art, Department of Biology, 10100 Balikesir, Turkey
Abstract
Length-weight relationship, reproduction, sex ratio, sexual maturity, hepatosomatic
index and stomach contents of 291 lesser spotted dogfish Scyliorhinus canicula
(Linnaeus, 1758) were examined. These fish were collected from trawl hauls made in
Edremit Bay, the northern Aegean Sea, in 1998. Total lengths of sampled fish ranged
from 27.0-78.6 cm in males and 24.6-70.0 cm in females. Weight increased
allometrically for both sexes together with b=2.93. Reproduction activities continued in
all seasons with a relatively high rate of oogenesis in the summer. The overall sex ratio
(females and males) was 0.29:1. The mature females spawned successively two eggs in
each batch. It is found that differences between liver weights of males and females were
not significant (P>0.05). The food of dogfish was mainly composed of fishes and
decapod crustaceans.
Key words: Aegean Sea, Scyliorhinus canicula, biological parameters.
Introduction
The dogfish Scyliorhinus canicula (Linnaeus, 1758) is a very common small shark
inhabiting particularly over sandy, coralline, algal, gravel or muddy bottoms at about
30-110 m depth. It is distributed in the Mediterranean and the Atlantic from Portugal to
Morocco and Canaries. It is oviparous, with a single egg laid per oviduct at a time
(WHITEHEAD et al., 1984; AKŞİRAY, 1987; COMPAGNO, 1999). It feeds on
molluscs and crustaceans, small cephalopods, polychaeta worms, and small bony fishes
(ELLIS and SHACKLEY, 1997; OLASO et al., 1998) RODRIQUEZ-CABELLO and
SANCHEZ (2005) estimated mortality rates of S. canicula in the Cantabrian Sea.
Although the more recent list of elasmobranch species from the seas of Turkey
(TORCU and AKA, 2000; TORCU-KOÇ et al., 2005; KABASAKAL, 2002) has
included a total of 28 confirmed species from the Turkish coast of the Aegean Sea, the
information on the distribution, bio-ecological aspects and population structures of
nearly all of these 28 species is still scarce, The lesser spotted dogfish is the most
17
abundant shark in Turkey (the Northern Aegean Sea). Despite its abundance, S.canicula
has never had a high commercial value in Turkey (CİHANGİR et al., 1997;
KABASAKAL and KABASAKAL, 2004). It is caught as by-catch in demersal fisheries
and is mainly used for bait for crab and whelk fisheries (CLARKE, 1999). Many sharks
are commonly present as by-catch in commercial fisheries. It is now well known that
by-catch is of great concern both ecologically and in terms of fishery management,
particularly in shrimp fisheries (HALL, 1996; CEDROLA et al., 2005).
In previous studies from the Turkish coasts on, GELDİAY (1969), AKŞİRAY
(1987), CİHANGİR et al. (1997), and AKA-ERDOĞAN et al. (2004) gave the
maximum lengths. KABASAKAL (2001) and AKA-ERDOĞAN et al. (2004) noted the
feeding habits of lesser spotted dogfish from the Turkish Seas.
The aim of the present study is to provide information on some biological
features of the lesser spotted dogfish in Edremit Bay.
Materials and Methods
A total of 291 specimens were collected with trawl at monthly intervals, in 1998.
Sampling location was in Edremit Bay (the Northern Aegean coast of Turkey) between
Altınoluk and Bozburun (Fig. 1). This bay occupies an area of 34.5 km from east to
west, 25.5 km from north to south between 39°17’ and 39°34’N, 26°57’ and 26°34’E.
Figure 1. Sampling area in Edremit Bay.
Trawling was done only during daytime at depths ranging from 45 to 60 m.
Duration of hauls was about 2 hours with a speed of 2 miles per hour. The trawl was
equipped with a 22 mm stretched mesh size at the cod-end.
18
Total length (TL) of each fish was measured to the nearest 0.5 cm. After the
total weight measurements, dissected parts (liver, stomach, somatic, and gonad weight)
weighed to the nearest 0.01 g. The gonads were macroscopically examined to determine
the sex and reproductive stage. The five-point maturity scale employed here was a
simplified version of PINTO and ANDREU (1957) maturity scale (stage I-virgin or
resting; II-maturing stage; III-premature stage; IV-spawning; V-post spawning stage).
For length frequency distribution 0.5 cm class interval (RICKER, 1975). The
length-weight relationship was estimated by the equation: W=a*Lb, where W is the
weight in grams, TL the total length in cm, b the growth exponent factor, and a is a
constant (y-intercept). The hypothesis of Allometric growth (RICKER, 1975) was tested
using a t-test.
Spawning period was determined by analyzing the monthly percentages of
mature individuals (on the basis of macroscopic classification). Sex ratio was analyzed
monthly (on the basis of macroscopic classification). Deviations from 1:1 null
hypothesis were statistically tested by (χ2 ) analysis (SOKAL and ROHLF, 1994).
Livers of all individuals were removed and weighted. Hepatosomatic index
(HSI %), the ratio of liver weight to somatic weight was estimated.
The stomachs were removed and preserved in 4% formaldehyde or 70%
alcohol solution for later analysis. Where possible, prey items were identified to species
or the nearest possible taxonomic level, and counted under binocular microscope
(HYSLOP, 1980; LABROPOULOU et al., 1998; CORTES, 1999). Generally, results of
dietary analyses include one or more of indices: by weight (W) and percentage
frequency occurrence (FO): W%: the ratio of total weights of a particular prey type to
the total weight of all stomach items, FO%: the ratio of the number of stomachs
containing a given type of prey to the total number of stomach examined; vacuity index,
V= Ev*100/N; with N: the number of fish examined, Ev: the number of fish with empty
stomach. Chi-square (χ2 ) was done according to vacuity index in variations of total
length and seasons. (TUSET et al., 1996; CORTES, 1999).
Results
Length and Weight Frequency Distribution by Sex
Males ranged from 270 to 786 mm, whilst the range of for females 246-700
mm TL and 246-786 mm for all fish (Table I). The most of the individuals in our
samples ranged from 440 to 470 mm (67 %) (Fig. 2A).
Males ranged from 63.67-2424 g, whilst the range for females 75.14-1682 g W
and 63.67 - 2424 g for all fish (Table I). The majority of the sampled fish ranged from
302 to 394 g (72 %) (Fig. 2B).
Differences in the mean length values were statistically significant between
sexes, but not in the mean weight values.
19
Figure 2. A-B. Total Length (A) and Weight (B) frequency distribution of male and
female S. canicula.
Table 1. Total length (mm), weight (g) values (SE: Standard error) by sex
Female
Mean ± SE
MinMax
W
TL
75.141682
246-700
Male
Min-Max
558.90±55.071
477.5±13.916
63.672424
270-786
Mean ± SE
t test
All fish
Min-Max
465.52±26.767
>0.05
479.24±5.001
<0.05
63.672424
246-786
Mean ± SE
486.695±24.235
478.845±4.977
Length-weight relationship
Allometric growth was observed for all fish. Regression parameters for all
individuals are presented in Table 2. No significant difference in b values was found
between males and females (t-test, t < t0.05, n > 200 =1.65). Length growth is faster than
weight growth.
Table 2. All fish; parameters of the lenght-weight relationship (W = a*Lb) (a: Intercept,
b: Slope, SE: Standard error, N: Number of specimens, r2: Determination
coefficient)
N
291
a
All fish
6*10-7
(t-test, ts > t 0.05,n>200 = 1.96)
B
2.9276
SE (b)
182.8578
r2
0.8266
t-test
-3.958
Sex ratio
The samples contained 66 females and 225 males. The overall ratio of females
to males was (F:M) 1:3.41, the males were significantly more abundant (χ2 = 86.87,
p<0.05).
20
According to macroscopic identification, lesser-spotted dogfish reproduce
through out the year. It was seen that the mature females spawned successively two
eggs in each batch.
Hepatosomatic İndex
Hepatosomatic index (HSI %)
Differences rates of liver weights of males and females to total body weight
(1.3 % and in 1.14 %, respectively) were not statistically significant according to min,
max, and mean HIS (%) values (ANOVA=1.328, p>0.05) (Fig. 3). The smallest
observed HSI (%) value was in Autumn with 1.493 and the highest HSI (%) value was
in Spring with (10.726) for females.
12
10
8
6
4
2
0
F
M
Spring
F
M
F
M
Summer
Autumn
Seasons and sexs
F
M
Winter
Figure 3. Variations in values of hepatosomatic index by sex and seasons.
Feeding
Variations of ratios of the number of fish with empty stomach by length groups
and seasons are given in Fig. 4. Winter is excluded since no fish with empty stomach
was found in this period. Seasons affected the vacuity index, the ratio of feeding
increased in summer and autumn (χ2 test, p<0.05). But, the influence of length on
vacuity index is not statistically significant (χ2 test, p>0.05)
Spring
Summer
Autumn
Frequency
40
30
20
10
0
200
400
500
T otal Length (mm)
600
700
Figure 4. Vacuity index values according to total length and seasons.
21
The food was primarily consisted of teleosts and crustaceans. For lesserspotted dogfish of 450 mm, indeterminated material was the most with 67.4%.
Percentage frequency of occurrence (FO %) by length groups and sexes are given in
Fig. 5. The reason why that is the most of samples caught couldn’t be stored for a long
time in the summer, food content was mostly digested. Percentage frequency of
occurrence (FO %) by length groups and sexes is given in Fig. 5.
450
400
350
250
200
Spring
Summer
Indeterminus
Teleostei
Indeterminus
Crustacea+Tele
ostei
Crustacea
Teleostei
Teleostei
Indeterminus
100
80
60
40
20
0
Autumn
Figure 5. Variations stomach contents of S. canicula to length groups and seasons.
As seen in Fig. 5, stomach contents of S. canicula of >400-450 mm were
determined. A list of identified food organisms was presented without indeterminated
material (Table 3). Values of W (%) in Table 3 were also estimated with no
indeterminated material.
Table 3. Composition of the food of S. canicula in Edremit Bay in terms of W (%)
Prey category groups
Total Length
400
450<
Crustacea
2.15
Decapoda
5.03
Caridea
12.96
Teleostei
73.32
59.73
Sardina pilchardus
26.68
13.07
Merluccius merluccius and S. pilchardus
100
Caridea and Teleostei
7.05
*The higher taxonomic groups include organisms which could not determine to species
level.
<250
22
Discussion
S. canicula is considered as a common species in the northern Aegean Sea
(PAPACONSTANTINOU and TSIMENIDES, 1979; BENLİ et al., 2000;
KABASAKAL 2002; KABASAKAL and KABASAKAL, 2004).
There were significantly more males than females observed, due to the
dominance of males in 1998. Females are known to predominate in July in the
Cantabrian Sea (RODRIQUEZ et al., 1998); in January and June in the Bristol Channel
(ELLIS and SHACKLEY, 1997); in Summer from the northern Aegean Sea of Turkey
(CİHANGİR et al., 1997). The apparent monthly differences in the sex ratio may be the
result of unisexual shoaling and not geographical segregation. The values of some
biological aspects of S. canicula in the studies were showed in Table 4. CAPAPE
(1977) noted that the males and females mature at lengths of 40 and 45 cm, respectively
along the Tunisian coast. CAPAPE et al. (1991) noted maximum length 55 cm for
males, 51 cm for females from the gulf of Lion, while SÁNCHEZ et al. (1995)
presented maximum length 65 cm for all individuals from Galicia and Cantábrico.
JARDAS (1979) stated that the males and females mature at lengths of approximately
33 and 40 cm, respectively from the Adriatic Sea. ELLIS and SHACKLEY (1995)
suggested that the males and females mature at lengths of approximately 52 and 55 cm.
RODRIQUEZ-CABELLO et al. (1998) reported that the females attained first sexual
maturity at length of 54.2 cm, while IVORY et al. (2002; 2004) stated that the males
and females mature at lengths of 53.5-57.0 cm, respectively. As the previous studies
carried out along Turkish coasts, GELDİAY (1969) and AKŞİRAY (1987) established
that maximum lengths were 80 cm and 150 cm, respectively. CİHANGİR et al. (1997)
noted total lengths of 54.6 cm for males and 51.7 cm for females. The findings of our
study are nearly in agreement with the previous assessments.
Egg lying occurs throughout the year, except for a break during the autumn
(MELLINGER, 1983; CAPAPE et al., 1991; ELLIS and SHACKLEY, 1995;
CİHANGİR et al., 1997). MELLINGER (1983) reported that egg laying rates of 44
eggs in 187 days, 20 in 148 days and 24 in 144 days for three Mediterranean specimens.
CAPAPE et al. (1991) pointed out that females lay 17 eggs. The 10 mature female fish
maintained in captivity from June to December laid a combined total of 177 eggs over
214 days from British Channel (ELLIS and SHACKLEY, 1995), while CİHANGİR et
al. (1997) found that one egg in each oviduct canal of a female from the northern
Aegean Sea. RODRIQUEZ-CABELLO et al. (1998) reported that at least one in six
adult female dogfish carried egg-capsules from the Cantabrian Sea during 1994-1995.
Our findings confirm that of CİHANGİR et al. (1997).
CRAIK (1978) mentioned that liver weights of females were more than liver
weights of males in pre and during vitellogenesis. CRAIK (1978) pointed out that HSI
values were higher in females than males and varied in two sexes according to seasons,
while CİHANGİR et al. (1997) reported that no difference was determined between
sexes, except for Spring. Even if this study is in agreement with that of CİHANGİR et
al. (1997), differences rates of liver weights of males and females to total body weight
are not statistically significant in seasons.
23
It has been reported that S. canicula feeds on decapods crustaceans, molluscs, and
teleosts (LYLE, 1983; ELLIS and SHACKLEY, 1995; ELLIS and SHACKLEY, 1996;
OLASO et al., 1998). LYLE (1983) studied feeding habits of S. canicula in the Isle of
Man. And found that diet composed of molluscs with (20-48 %). According to
KABASAKAL (2001), S. canicula feeds on fishes, crustaceans, and cephalopods. Our
findings confirm the relevant literature, except for LYLE (1983).
References
AKŞİRAY, F., 1987. Türkiye Deniz Balıkları ve tayin anahtarı. II. Baskı, İstanbul,
İ.Ü.Rekt.Yay. No: 3490, pp 811.
BENLİ, H. A., CİHANGİR, B., BİZSEL, K. C., BİLECİK, N., BUHAN, E., 2000. Ege
Denizi’nin demersal balıkçılık kaynakları üzerine bir araştırma, Tarım ve Köyişleri
Bakanlığı, Tarımsal Araştırmalar Genel Müdürlüğü, Ankara, pp 90.
CAPAPE, C., 1977. Contribution a la biologie des Scyliorhinidae des cotes tunisiennes.
I. Scyliorhinus canicula (L., 1758). Repartation geographique et batymetrique,
sexualite, reproduction, fecundite. Bull. Off. Natn. Pech. Tunisie 1 (1), 83-101.
CAPAPE, C., TOMASINI, J. A., BOUCHEREAU, J. L., 1991. Aspects of the
reproductive biology of the small spotted dogfish Scyliorhinus canicula (Linnaeus,
1758) (Pisces, Scyliorhinidae) from of the Gulf of Lion (southern France)
Ichtyophysiol-Acta. 14, 87-109
CEDROLA, P. V., GONZÁLEZ, A. M., PETTOVELLO, A. D., 2005. Bycatch of
skates (Elasmobranchii: Arhynchobatidae, Rajidae) in the Patagonian red shrimp
fishery. Fish. Res., 71(2), 141-150.
CİHANGİR, B., ÜNLÜOĞLU A., TIRAŞIN, M. E., 1997. Kuzey Ege Denizi’nde
kedibalığı (Chondrichthyes Scyliorhinus canicula (L., 1758)’nin dağılımı ve bazı
biyolojik özellikleri. Akdeniz Balıkçılık Kongresi, 9-11 Nisan, İzmir, pp 585-603.
CLARKE, M., 1999. A brief review of available data on elasmobranchs in Irish waters.
Working document for the ICES Study Group on Elasmobranch Fishes, March 1999,
pp 12.
COMPAGNO, L. J. V., 1999. Checklist of living elasmobranchs. In: W.C. HAMLETT
(ed.) Sharks, skates, and rays: the biology of elasmobranch fishes. John Hopkins
Univ. Press, Maryland. pp 471-498.
CORTÉS, E., 1999. Standardized diet compositions and trophic levels of sharks. ICES
J. Mar. Sci. 56, 707-717.
CRAIK, J., C., A., 1978. An annual cycle of vitellogenesis in the elasmobranch
Scyliorhinus canicula. J. Mar. Biol. Ass. U.K. 58, 719-726.
DOREL, D. 1985. Poissons de l'Atlantique nord-est relations taille-poids. Institut
Francais de Recherche pour l'Exploitation de la Mer., Paris, pp 165.
ELLIS, J.R., M. G. PAWSON, SHACKLEY, S. E., 1996. The comparative feeding
ecology of six species of shark and four species of ray (Elasmobranchii) in the northeast Atlantic. J. Mar. Biol. Ass. U.K. 76 (1), 89-106.
ELLIS, J.R., SHACKLEY S. E., 1995. Ontogenetic changes and sexual dimorphism in
the head, mouth and teeth of the lesser spotted dogfish. J. Fish. Biol. 47, 155-164.
24
ELLIS, J.R., SHACKLEY S. E., 1997. The reproductive biology of Scyliorhinus
canicula in the Bristol Channel, U.K. J. Fish Biol. 51, 361-372.
ERDOĞAN-AKA, Z., TORCU-KOÇ, H., TÜRKER-ÇAKIR, D., 2004. Sexual
dimorphism in the small-spotted dogfish Scyliorhinus canicula (L., 1758) from the
Edremit Bay (Turkey). Annales. Ser. Hist. Nat. 14 (2), 165-170.
GELDİAY, R., 1969. İzmir Körfezi’nin başlıca balıkları ve muhtemel invasionları. E.Ü.
Fen Fak. Monog., Seri 11, pp 135.
GIBSON, R. N., EZZINI, I. A., 1987. Feeding relationships of a demersal fish
assemblage on the west coast of Scotland. J. Fish Biol. 31, 55-695.
HALL, M. A., 1996. On bycatches. Rev.Fish Biol. Fish. 6 (3), 319-352.
HYSLOP, E., J., 1980. Stomach content analysis. A review of method and their
application. J. Fish Biol. 17, 411-429.
IVORY P., JEAL, F., NOLAN, C. P., 2002. Age determination, growth and
reproduction in the lesser spotted dogfish Scyliorhinus canicula (L., 1758). NOAA
SCR Doc, Scientific Council Meeting, September 2002.
IVORY P., JEAL, F., NOLAN, C. P., 2004. Age, determination, growth and
reproduction in the lesser-spotted dogfish, Scyliorhinus canicula, e-journal of
Northwest Atlantic Fishery Science, 35 (2), September 2004.
JARDAS, I., 1979. Morphological, biological and ecological characteristics of the lesser
spotted dogfish, Scyliorhinus canicula (Linnaeus, 1758) population in the Adriatic
Sea, Institut za Oceanografiju i Ribastvo-Split 4 (2-3), 1-104.
KABASAKAL, H. KABASAKAL, E., 2004. Sharks captured by commercial fishing
vessels off the coast of Turkey in the northern Aegean Sea. Annales Ser.Hist.nat. 14
(2), 171-180.
KABASAKAL, H., 2001. Preliminary data on the feeding ecology of some selachians
from the north-eastern Aegean Sea. Acta Adriat. 42 (2), 111-118.
KABASAKAL, H., 2002. Elasmobranch species of the seas of Turkey. Annales
Ser.Hist.nat. 12 (1), 15-22.
KAISER, M. J., SPENCER, B. E., 1993. Opportunistic feeding on benthos by fishes
after the passage of A 4-m beam trawl. ICES C.M. 1993/G, 27.
KOÇ-TORCU, H., AKA, Z., TÜRKER-ÇAKIR, D., 2004. Fishes of Saros Bay
(Northern Aegean Sea ), J. Sci. and Tech., BA.U., 6, 2.
LYLE, J. M., 1983. Food and feeding habits of the lesser spotted dogfish, Scyliorhinus
canicula (L.) in Isle of Man waters, J. Fish Biol. 23, 725-737.
MACPHERSON, E., 1979. Relations trophiques des poisons dans la Méditerranée
occidentale. Rapp. Comm. Int. Expl. Sci. Mer Médit. 25/26, 49-58.
MELLINGER, J., 1983. Egg- case diversity among dogfish, Scyliorhinus canicula (L.,
1758): a study of egg laying rate and nidamental gland secretory activity. J. Fish Biol.
22, 83-90.
MERELLA, P., QUETGLAS, A., ALEMANY CARBONELL, A. F., 1997. Lengthweight relationship of fishes and cephalopods from the Balearic Islands (western
Mediterranean). Naga ICLARM Q. 20 (3/4), pp 66-68.
25
MILLÁN, M., 1992. Reproductive characteristics and condition status of anchovy
(Engraulis encrasicolus, L.) from the. Bay of Cadiz (S.W. Spain). Fish. Res. 41, 7386.
OLASO, I., VELASCO, F., PEREZ, N., 1998. Importance of discarded blue whiting
(Micromesistius poutassou) in the diet of lesser spotted dogfish (Scyliorhinus
canicula) in the Cantabrian Sea, ICES J. Mar. Sci. 55 (3), 331-341.
PAPACONSTANTINOU, C., TSIMENIDES, N., 1979. Some uncommon fishes from
the Aegean Sea. Cybium 7, 3-14.
PINTO , J., ANDREU, B., 1957. Echelle pour la caracterisation des pevolution de
I’ovaire de sardine, Sardina pilchardus (Walb.) en raport avec I’histophysiologie de
la ganade. Proc.dec.Pap. Gen.Fish Count. Medit. 4, 393-411.
RICKER, W.E., 1975. Computation and interpretation of biological statistics of fish
populations, Bull. Res. Fish Board of Can. 191, pp 382.
RODRIQUEZ-CABELLO, C., SNACHEZ, F., 2005. Mortality estimates of
Scyliorhinus canicula in the Cantabrian Sea, using tag-recapture data. J. Fish Biol. 66
(4), 1116.
RODRIQUEZ-CABELLO, C., VELASCO, F., OLASA, I., 1998. Reproductive biology
of the lesser spotted dogfish Scyliorhinus canicula (L., 1758) in the Cantabrian Sea.
Sci. Mar., 62 (3), 187-191.
SÁNCHEZ, F., F. DE LA GÁNDARA, GANCEDO R., 1995. Atlas de los peces
demersales de Galicia y el Cantábrico. Otoño 1991-1993. Publicaciones Especiales,
Instituto Español de Oceanografia, Madrid, Spain (20), pp 100.
SOKAL, R.R., ROHLF, F.J., 1994. Biometry: the Principles and Practice of Statistics in
Biological Research, 3rd edn., New York: Freeman and Co., Newyork, pp 859.
TUSET, M., GONZALES, J. A., GARCIA-DIAZ, M. M., SANTANA, J. I., 1996.
Feeding habits of Serranus cabrilla (Serranidae) in the Canary Islands. Cybium 20,
161-167.
WETHERBEE, B. M., GRUBER, S. H., CORTES, E., 1990. Diet, feeding habits,
digestion, and consumption in sharks, with special reference to the lemon shark,
Negaprion brevirostris. In: Jr. PRATT, H., L., GRUBER, S. H., TANIUCHI, T.
(eds.), Elasmobranchs as living resources: advances in the biology, ecology,
systematics, and the status of the fisheries, NOAA Tech. Rep. NMFS 90, pp 29-47.
WHITEHEAD, P.J.P., BAUCHOT, M. L., HUREAU, J.C., NILSEN, J., TORTONESE,
E., 1984. Fishes of the North-Eastern Atlantic and the Mediterranean, Vol. 1, Paris,
Unesco, pp 510.
26
Table 4. The values of some biological aspects of S. canicula.
References
Macpherson
1979
Year
19761978
Locality
Dorel 1985
19751976
27
199193
19811985
Cihangir et al.,
1997
Merella et al.,
1997
Ivory et al.,
2004
This study
16.032.12
22.3326.0
19951996
TL (cm)
Fema
le
Male
214235
193206
L-W relationship
All
Fish
a
b
HSI
r
2
Female
Food
Male
All Fish
zoobethos
Bay of
Biscay
EastandWest
Channel
Dorel 1985
Ellis et al., 1996
Male
N
All
Fish
Balearic Sea
Jardas 1979
Gibson and
Erzini 1987
Wetherbee et
al.,1990
Kaiser and
Spencer 1993
Sánchez et al.,
1995
Ellis and
Shackley 1995
W (g)
Femal
e
2.53
285
20-30
0.0036
2.779
376
37103
0.0031
3.029
2.67
UK.Scotland
crustacea
zoobenthos
Spain
teleost
UK.Englan
benthic
crustaceans
Galiciaand
Cantábrico
Bristol
Channel
Northeaster
Atlantic
520650
Northern
Aegean Sea
517
650
490550
490650
-
-
-
7.0714.09
2.726.64
zoobenthos
Balearic
Islands
Northwest
Atlantic
546
262
75.141682
63.672424
63.672424
291
103700
246700
104710
270786
-
0.001
3.21
0.919
75421
0.0016
3.160
0.997
246786
6.10-7
2.93
0.83
teleost,
decapod
crustaceans
1.49310.726
2.628.149
teleost
Proc. of the Int. Workshop on Med. Cartilaginous Fish with Emphasis on South.- East. Med., 14-16 Oct. 06, Istanbul-Turkey
DIFFICULTIES IN AGE READINGS FROM DORSAL SPINES OF
SPINY DOGFISH Squalus acanthias L., 1758
Sefa Ayhan DEMİRHAN1, Hamdi ÖĞÜT2, Semih ENGİN3,
Nuri BAŞUSTA4 and Ercüment GENÇ1
2
1
Mustafa Kemal University, Faculty of Fisheries, 31040 Serinyol, Antakya/Hatay, Turkey
Karadeniz Technical University, Surmene Faculty of Marine Sciences, 61530 Surmene/Trabzon, Turkey
3
Black Sea Technical University, Faculty of Fisheries, Rize, Turkey
4
Harran University, Ata Fisheries Research and Application Center, Sanliurfa, Turkey
E-mail:nbasusta@hotmail.com
Abstract
The structural problems of using spines for determining the age of spiny dogfish
Squalus acanthias L., 1758 were examined. The main problems connected with this
method were: the occurrence of spines with wiped surfaces (18 % of first and 12 % of
second spines), broken spines (8 % of first and 6 % of second spines), both broken and
wiped surfaces (20 % of first and 12 % of second spines), and spines with complicated
surfaces (31 % of first and 31 % of second spines). While these problems sometimes
made age readings impossible (70 % of first and 37 % of second spines), other spines
were used successfully to determine age despite the problems. The frequency of these
problems was different between first and second dorsal spines.
Key words: Spiny dogfish, Black Sea, spiny age determination.
Introduction
The spiny dogfish Squalus acanthias L., 1758 is a common shark in the North Atlantic
and North Pacific. As the spiny dogfish grows slowly and has a low reproduction
potential (COLVOCORESSES and MUSICK, 1980), it of importance to carefully
monitorpopulation for a sustainable fishery. Stock assessment of any fish species
requires estimates of growth rates, maximum age, cohort structure and age of maturity,
all of which rely on accurate estimates of age. Age determination of all elasmobranchs
is a difficult process because of lack of calcified otholits and scales. Reading annuli
externally from the second dorsal spine is the most preferred method for determining
the age of spiny dogfish populations (HOLDEN and MEADOWS, 1962; KETCHEN,
1975; SOLDAT, 1982; NAMMACK, 1985; POLAT and GUMUS, 1995). The spine
consists of an outer enamel layer, a pigment layer, three layers of dentine, and a central
pulp cavity. The annulus is formed as the dentine layers do not grow at the same rate as
the upward growth of spine in different seasons. When spine growth is reduced,
pigments are concentrated and the enamel layer thickens, producing an annulus
(MCFARLANE and BEAMISH, 1987). Annual formation of annuli has not been
validated through direct methods, but several indirect methods have been used. Length-
28
frequency analysis was used by BONHAM et al. (1949), HOLDEN and MEADOWS
(1962) and KETCHEN (1975). Monthly variation in colour of the basal band
(HOLDEN and MEADOWS, 1962), mercury accumulation (KETCHEN, 1975),
differences in length at known stages of pregnancy (BONHAM et al., 1949;
KETCHEN, 1975), and tagging studies (BONHAM et al., 1949) have also been used.
JONES and GEEN (1977) measured variations in elemental composition within
vertebrae with an X-ray spectrometric technique and found them to correspond nearly
identically with dorsal spine annulus. MCFARLANE and BEAMISH (1987) have
identified these bands to be annual with oxytetracycline (OTC) injections.
In this study, the difficulties associated with the most preferred method for determining
the age of spiny dogfish were studied.
Materials and Methods
This study was conducted in the Southern Black Sea (Fig. 1) between 2000 and 2003.
A total of 118 dogfish were captured by longline (DEMİRHAN et al., 2004) and
commercial purse seiners and gill-netters.
Figure 1. Sampling area
The first and second dorsal spine was removed by placing the knife posterior to
the spine. A cut was made parallel to the base of the spine down into the muscle tissue.
A second cut was made anterior to the spine until reaching the first cut (Fig. 2a and b).
The spines were placed into a labelled envelope, and frozen until laboratuary analysis.
29
Spines were examined by using the Photoshop 7.0TM program on computer after having
been photographed digitally by using a Sony 5.0 megapixelTM digital camera.
Figure 2. a) Spine removing method
b) Spine
Results and Discussion
The age of 118 specimens was read by using the spine reading method. The age of 9
specimens were read by using only the first spine, and 50 specimens were read by using
only second spine. The age of 59 specimens was read by using both spines.
Age readings are given in Fig. 3. The reasons for difficulties encountered while
determining age were (in order of importance) (1) spines with wiped surfaces (lack of a
pigment layer and annual rings on the spine surfaces), (2) broken spines (the tip of the
spines were broken or eroded), (3) spines with both broken and wiped surfaces, and (4)
spines with complicated surfaces (the surfaces of the spines had collapsed/corrupted the
annual ring on the spine base or surface) (Fig. 4).
Figure 3. Spine of female specimen of 134.5 cm total length (a, first dorsal
spine; b, second dorsal spine)
30
1) wiped surfaces
2) broken spine
(a) 1st spine (b) 2nd spine
1) wiped spine base
3) broken and wiped spines
2) complicated spine surfaces 3) complicated spine surfaces
Figure 4. Main problems faced with age readings
Two criteria were used for ageing studies; the age readings had to be validated
for accuracy (1) and the age readings had to be repeated by using validated methods (2)
(CAMPANA, 2001). Also, the importance of using both spines together (1), as well as
counting all dark bands and ridges occurring on the enameled surfaces together (2) was
not ignored. Annual marks on the spine surface (dark bands and ridges) was different
between first and second dorsal spines (Table 1).
Both spines were used to determine the age of 59 out of 118 specimens. Both
dark bands and ridges were used to determine age using the first 24 spines and 22 of the
second spines of a total of 59 spines. The age of 14 % of 118 specimens were
determined by using the two above mentioned criteria (the use of both spines together
and both dark bands and ridges that occur on enameled surfaces). All the first dorsal
spines were shorter than the second dorsal spines, and the annual bands were more
closely pressed together at the base of the first spines. Generally, first dorsal spines were
broken and had eroded and wiped surfaces. It was therefore difficult to read the first
dorsal spines. On the other hand, the annual bands were separated from each other on
the surfaces of the second dorsal spines, and this made readings easier (Fig. 5).
31
Table 1. Evaluation of spines in age readings
First Spine
Age readings from only first
dorsal spines
Only pigment band readings
Only ridge readings
Both pigment band and ridge
readings
Readings from both of spines
Only pigment band readings
Only ridge readings
Both pigment band and ridge
readings
Number
2
4
Second Spine
Age readings from only second
dorsal spines
Only pigment band readings
Only ridge readings
3
Both pigment band and ridge readings
12
59
23
12
Readings from both of spines
Only pigment band readings
Only ridge readings
59
24
13
24
Both pigment band and ridge readings
22
9
Figure 5. Use of spines and structures
32
Number
50
21
17
KETCHEN (1975), JONES and GEEN (1977), BEAMISH and MCFARLANE
(1985), MCFARLANE and BEAMISH (1987) stated that readings from second dorsal
spines were reliable. It can be said that age readings from just second dorsal spines (50
specimens) and both of the spines (59 specimens) were reliable in this study. Thus 92 %
of age readings (109 of 118 specimens) were considered as reliable.
There are several advantages to the method for determining age using dorsal
spines in this study. The spines were examined by using high resolution photos. The
images could be filtered by using the PhotoShop 7.0TM program. This made it easier to
identify and count annual growth bands. Lighting could be used to expose annual ridges
on the spine surface. Electronic records can be saved indefinitely without compromising
the samples. This method allows sensitive measurements on spine dimensions and
supplies a standardization on readings.
References
BEAMISH, R., MCFARLANE, G. A., 1985. Annulus development of the second dorsal
spine of the spiny dogfish (Squalus acanthias) and its validity for age determination.
Can. J. Fish. Aquat. Sci. 42, 1799-1805.
BONHAM, K., SANDFORD, F.B., CLEGG, W., BUCHER, G.C., 1949. Biological and
Vitamin A studies of dogfish landed in the State of Washington (Squalus suckleyi).
Washington Department of Fisheries, Research Bulletin 49A, 83-113.
CAMPANA, S. E., 2001. Accuracy, precision and quality control in age determination,
including a review of the use and abuse of age validation methods. J. Fish. Biol. 59,
197-242.
COLVOCORESSES, J. A., MUSICK, J. A., 1980. A preliminary evaluation of the
potential for a shark fishery in Virginia. in Special Report in Applied Marine Science
and Ocean Engineering 234, Gloucester Point, VA, USA, Virginia Institute of Marine
Science, pp 1-39.
DEMIRHAN S. A., ENGIN, S., CAN M. F., 2004. Doğu Karadeniz’de Dip Paraketası
İle Mahmuzlu Camgöz ve Vatoz Avcılığı Üzerine Bir Ön Çalışma. Ulusal Su Günleri
Sempozyumu 6-8 Eylül 2004. İnciraltı, İzmir.
HOLDEN, M. J., MEADOWS, P. S., 1962. The structure of the spine of the spur
dogfish (Squalus acanthias L.). and its use for age determination. J. of M. Biol. Ass.
of the U. K. 42, 179-197.
JONES, B. C., GEEN, G. H., 1977. Age determination of an Elasmobranch (Squalus
acanthias) in British Columbia waters. J. Fish. Res. Board Can. 34, 2067-2078.
KETCHEN, K. S., 1975. Age and growth of dogfish Squalus acanthias in British
Columbia Waters. J. Fish. Res. Board Can. 32, 43-59.
MCFARLANE, G. A., BEAMISH, R. J., 1987. Validation of the dorsal spine method of
age determination for spiny dogfish. In: R.C. SUMMERFELT and G.E. HALL (eds).,
Age and Growth of Fish. Iowa State University, Press, Ames., pp. 287-300.
33
NAMMACK, M., 1985. Age, growth and fecundity in spiny dogfish (Squalus
acanthias) in the western North Atlantic. Master Thesis, College of William and
Mary.
POLAT, N., GUMUS, A., 1995. Age Determination of Spiny Dogfish (Squlaus
acanthias L, 1758) in Black Sea waters. I. J. A. 47 (1), 17-24.
SOLDAT, V.T., 1982. Age and size of spiny dogfish, Squalus acanthias, in the
northwest Atlantic. Northwest Atlantic Fisheries Organization Scientific Council
Studies 3, 47-52.
34
Proc. of the Int. Workshop on Med. Cartilaginous Fish with Emphasis on South.- East. Med., 14-16 Oct. 06, Istanbul-Turkey
SEDIMENT STRUCTURE AND OCCURRENCE OF SKATES AND
RAYS INHABITING IN BABADILLIMANI BIGHT LOCATED IN
NORTHEASTERN MEDITERRANEAN
Hacer YELDAN and Dursun AVŞAR
Cukurova University, Faculty of Fisheries, 01330 Balcalı/Adana, Turkey. E-mail: hacyel@cu.edu.tr
Abstract
This study was carried out between May 1999 and May 2000 in Babadılimanı Bight
located in Northeastern Mediterranean coast of Turkey. Raja clavata, Raja radula and
Raja asterias were the most common skates in the region while the most common rays
of the territorial area were Dasyatis pastinaca and Gymnura altavela. In addition, for
the identification of sediment composition of the sea bottom where these species
distributed along the Northeastern Mediterranean, Grain Size Analysis was carried out
by using the samples taken from 3 depth ranges in the Babadıllimanı Bight. In terms of
the habitat selection, it was found that skates preferred highly silty bottom while rays
were more densely distributed along the shallower areas and sandy silts.
Key words: Mediterranean Sea, sediment, continental shelf, skates and rays.
Introduction
Although approximately 700 000 tonnes of skates and rays are caught in the world in a
year on average (BONFIL, 1994; FRISK et al., 2001); according to State Institute of
Statistics Prime Ministry Republic of Turkey’s 1995 to 2002 statistics the mean landing
values in Turkey are rather low, varying between 340 and 1575 tonnes per year, and the
annual statistics for these groups in Turkey are not given separately (DIE, 1995-2001).
Although elasmobranchs have become important fishery resources worldwide,
yet many aspects of their ecology suggest that they may susceptible to over exploitation
(HOLDEN 1974; 1977). In Turkey, skates and rays are considered as by-catch in
demersal fisheries, and some species eg. Raja clavata and Dasyatis pastinaca are landed
for consumption in some European countries (Italy and France). Geographic distribution
abundance, feeding habits and reproductive data for skates and rays in the Northeastern
Atlantic and the Mediterranean (WHEELER, 1969; NOTTAGE and PERKINS, 1980;
WHITEHEAD et al., 1986; FISCHER et al., 1987; ESCHMEYER, 1999; DULCIC et
al., 2003) and extended seas located along the Turkish coast (ANONYMOUS, 1984;
AKSIRAY, 1987; BASUSTA et al., 1998; GUCU and BINGEL, 1994; KABASAKAL,
1994; BINGEL et al., 1996; BASUSTA and ERDEM, 2000; ISMEN, 2002; FILIZ and
TOGULGA, 2002; FILIZ and MATER, 2002; MATER et al., 2003) are mostly based
on systematic, comprehensive biology, distribution and the identification characteristic
35
of these groups, while data about the occurrence, ecology and sediment structure of
their habitat are rare. This study, in relation to others apart from general biology, deals
with sediment structure of their habitat and occurrence of skates and rays in the
Northeastern Mediterranean. Therefore this study contributes to the increased
knowledge of the ecology of skates and rays.
Materials and Methods
A total of 307 individuals were captured by deep-trawl net between May 1999 to May
2000 in Babadıllimanı Bight located in the Northeastern Mediterranean coast of Turkey.
In order to determine the sediment structure of Babadıllimanı Bight (330 23' 36" - 330
32' 57" N; 360 07" 00" - 360 09' 39" E), the study region of this research, only one
sampling was carried out in May 2000. The samples were collected from three different
stations located at 0-50, 50-100 and >100m depth ranges by using dredge (Fig. 1).
Samples were transferred to the laboratory in plastic bags in order to make Grain Size
Analysis. The analyses were carried out according to the Wentworth Scale. Sieves with
2, 1, 0.5 and 0.25 mm (in diameter) holes were used to shift the samples (RICHARD
and DAVIS, 1972). Afterwards, the samples were classified according to the particle
sizes. The particles between 2-1 mm in diameter were classified as gravels, and those
between 1-0.25 mm were sand and silt, while those smaller than 0.25 mm were clay.
Figure 1. The study area and the sampling stations.
Results
General Features of the Babadıllimanı Bight
In the Northeastern Mediterranean, the largest continental shelf area is located
between Iskenderun and Silifke. There are also some small areas in the western entrance
36
of this section. Among them Babadıllimanı Bight is the largest area of the region subject
to the fishing along the northeastern Mediterranean coast of Turkey. The bottom
structure of Mersin and Iskenderun Bays located in the region are mostly covered by
sand, silt, clay or mud; and therefore have a dynamic substratum structure. Due to this
formation, the bottoms of both bays are convenient for deep trawling, but the rest of the
region has a slopy, highly steep bottom.
The section where Babadıllimanı Bight lays is of typical Mediterranean
characteristics: it has a highly narrow continental shelf and is surrounded by very steep
mountains lying parallel to the coastline. Nearby inshore is mostly covered by rocks and
crags. Only the area of 6 miles length and 2-3 nautical miles width between Beşparmak
Island and Kızılliman Cape has a partly even floor, and its bottom is mostly covered by
clay and silt (OZYURT, 2003).
Sediment Structure
The results obtained from the sediment samples taken from the stations located
into the depth ranges of 0-50 m, 50-100 m and >100 m in Babadıllimanı Bight are given
in Fig. 2.
% 60
Sand
Silt
Clay
50
40
30
20
10
0
0-50
50-100
>100
Depth Range (m)
Figure 2. The sediment structure of Babadıllimanı Bight (%).
It seems that the 0-50 m depth range representing coastal region of
Babadıllimanı Bight is mostly covered by silt, and it is followed by sand and then, by
clay (Fig. 2). It is clearly seen that within the depth ranges, silt formation has uttermost
importance in 50-100 m depth range, but the silt percentage is higher compared to the 050 m depth range. Clay comes after the silt, and sand is lesser than the other two
sediment types in the region. Within the depth ranges silt structure is the main
component of the sediment in the area deeper than 100 m while clay follows this, and
sand constitutes the smallest proportion (Fig. 2).
37
Moving from the shallow coastal region to the deeper offshore, it seems that
the bottom is mostly covered with silt in all depth ranges, and the sand is also
significant in the sediment composition of coastal bottom structure, but it becomes less
and less noteworthy advancing towards the deeper waters. On the other hand, clay
becomes the second significant component after silt advancing to deeper bottoms, while
it is insignificant in the sediment structure of coastal bottoms (Fig. 2).
Distribution of Skates and Rays in the Region
The proportional distribution of skates and rays caught from Babadıllimanı
Bight and obtained results in this study considering depth ranges are given in Table 1.
Table 1. The proportional distribution of skates and rays in terms of depth ranges and
along the Babadıllimanı Bight
Species
Raja clavata
Raja radula
Raja asterias
Dasyatis pastinaca
Gymnura altavela
Total
0-50m
4.10
24.10
3.00
5.10
13.70
50.00
Depth ranges
50-100m
4.40
36.10
4.20
2.10
1.20
48.00
>100m
0.65
1.05
0.30
2.00
Total
9.15
61.25
7.50
7.20
14.90
100.00
As seen in Table 1, although the thornback ray (Raja clavata) is found in each
of three depth ranges, since it is more common in the first two depth ranges, and these
places mostly consist of silt while including sand to some extent. Therefore, it could be
claimed that this species prefer silty-sandy bottoms in the Northeastern Mediterranean.
However, the fact that this species exist proportionally more within 50-100 m depth
range than that of 0-50 m indicates that this species prefers silty regions within siltysandy areas more. R. radula seems to prefer the bottoms of 0-50 m and 50-100 m depth
ranges which are close to the coast and of sandy and silty formation, more than that of
>100 m depth range. Within these areas it chiefly prefers mostly silty regions, just as R.
clavata and R. asterias individuals do. (Table 1; Fig. 2).
Although the skates (R. clavata, R. radula and R. asterias) obtained during the
sampling period mostly prefer silty regions, it was found that the rays (D. pastinaca and
G. altavela) prefer shallower and sandy-silty regions -where two sediment types exist
nearly equally-compared to the other species. (Table 1; Fig. 2).
Discussion
The species related to this study are demersal and widely distributed in the waters of
Northeastern Mediterranean, and they prefer the sediment formation of sand, silt and
clay for habitation. In the study, although R. clavata and R. radula individuals occurred
38
within all of the three depth ranges, they were only extensively found within 0-50 and
50-100 m depth ranges.
It was also found that R. asterias preferred the same substratum as R. clavata
and R. radula inhabited, whereas Dasyatis pastinaca and Gymnura altavela individuals
were scattered within different environments. Although D. pastinaca individuals were
found within three depth ranges (0-50 m; 50-100 m; >100 m), G. altavela were
distributed abundantly within 0-50m depth range, but seldom within 50-100 m, and they
were not encountered at the substratum deeper than 100m. In literature, other studies
have only given some information about the geographical regions these species exist in
and the strata in which they distribute. Among them, WHEELER (1969), AKSIRAY
(1987), FISCHER et al. (1987), WHITEHEAD et al. (1986), BASUSTA et al. (1998;
2000), HAMLETT (1999) and MATER et al. (2003) state that these species are found
in nearly all the coastal waters: from hot seas to the warm and very cold seas of
Northern and Southern Hemisphere; and from very shallow areas to the depth of 200 m
and even up to 3000 m.
Additionally, considering their general distribution, it is stated that from skates
and rays individuals live on sandy-muddy benthic areas of all the Turkish coastal waters
(BASUSTA et al., 1998; MATER et al., 2003; FROSE et al., 2004). Consequently, it
seems that the structures of the substrata, considering the species examined in this study
are in harmony with those reported by other researchers.
References
AKSIRAY, F., 1987. Turkish Marine Fishes and Their Identification Sheets. Istanbul
Üni. Rektörlüğü Yay, No: 3490 II. Istanbul, pp 811. (in Turkish)
ANONYMOUS, 1984. Ülkemizde İnsan Gıdası Olarak Tüketim Alışkanlığı Olmayan
Köpek Balığı, Vatoz, Midye ve Pavuryanın Karadeniz’deki Yayılışı ve
Değerlendirilmesinin Araştırılması Projesi Ara Raporu. T.C. Tarım Orman ve
Köyişleri Bakanlığı Su Ürünleri Daire Başkanlığı Samsun Su Ürünleri Bölge
Müdürlüğü, Samsun, pp 35.
BASUSTA, N., ERDEM, Ü., 2000. İskenderun Körfezi Balıkları Üzerine Bir Araştırma.
TÜBİTAK. Turk. J. Zool 24, 1-19.
BASUSTA, N., ERDEM, Ü., ÇEVİK, C., 1998. İskenderun Körfezi Kıkırdaklı Balıkları
Üzerine Taksonomik Bir Çalışma. Celal Bayar Üniversitesi Fen-Edebiyat Fakültesi
Dergisi 1., 63-69.
BINGEL, F., GUCU, A. C., STEPNOWSKI., A., NIERMANN, U., KIDEYS, A. E.,
MUTLU, E., DOĞAN, M., KAYIKCI, Y., AVSAR, D., BEKIROĞLU, Y., GENÇ,
Y., OKUR, H., ZENGIN, M., 1996. Karadeniz Stok Tespiti Projesi Balıkçılık
Araştırmaları. TÜBİTAK DEBÇAG 74/g, DEBÇAG 139/G ve DEBÇAG 115/G
Final Raporu, Deniz Bilimleri Enstitüsü, Yorma-Trabzon, pp 172.
BONFIL, R., 1994. Overview of World Elasmobranch Fisheries. FAO Tech. Paper, No:
341, Rome, pp 119.
39
DIE, 1995. Su Ürünleri İstatistikleri, T.C. Başbakanlık Devlet İstatistik Enstitüsü, Yayın
No:1995, Devlet İstatistik Enstitüsü Matbaası, Ankara, pp 32.
DIE, 1996. Su Ürünleri İstatistikleri, T.C. Başbakanlık Devlet İstatistik Enstitüsü, Yayın
No:2075, Devlet İstatistik Enstitüsü Matbaası, Ankara, pp 40.
DIE, 1997. Su Ürünleri İstatistikleri, T.C. Başbakanlık Devlet İstatistik Enstitüsü, Yayın
No:2154, Devlet İstatistik Enstitüsü Matbaası, Ankara, pp 41.
DIE, 1998. Su Ürünleri İstatistikleri, T.C. Başbakanlık Devlet İstatistik Enstitüsü, Yayın
No:2302, Devlet İstatistik Enstitüsü Matbaası, Ankara, pp 35.
DIE, 1999. Su Ürünleri İstatistikleri, T.C. Başbakanlık Devlet İstatistik Enstitüsü, Yayın
No:2429, Devlet İstatistik Enstitüsü Matbaası, Ankara, pp 45.
DIE, 2000. Su Ürünleri İstatistikleri, T.C. Başbakanlık Devlet İstatistik Enstitüsü, Yayın
No:2752, Devlet İstatistik Enstitüsü Matbaası, Ankara, pp 45.
DIE, 2001. Su Ürünleri İstatistikleri, T.C. Başbakanlık Devlet İstatistik Enstitüsü, Yayın
No:2914, Devlet İstatistik Enstitüsü Matbaası, Ankara, pp 345.
DIE, 2002. Su Ürünleri İstatistikleri, T.C. Başbakanlık Devlet İstatistik Enstitüsü, Yayın
No:2112, Devlet İstatistik Enstitüsü Matbaası, Ankara, pp 40.
DULCIC, J., JARDAS, I., ONOFRI, V., BOLOTIN, J., 2003. The Rougtail Stingray
Dasyatis centroura (Pisces: Dasyatidae) and Spiny Butterfly Ray Gymnura altavela
(Pisces: Gymnuridae) from the Southern Adriatic. J. Mar. Biol. Ass. 83, 871-872.
ESCHMEYER, W.N., 1999. Catalog of fishes on-line, updated February 15, 2002.
[http:// www. Calacademy. org/ research/ ichthyology/ index.html].
FISCHER, W., BAUCHOT, M.–L., SCHNIDER, M., (eds). 1987. Fishes FAO
d’identification des especes pour les besoins de la peche. Mediterranee et mer Noir.
Zone de peche 37. Vertebres. Vol. 2, FAO, Rome, pp 761-1530.
FILIZ, H., MATER, S., 2002. A Preliminary Study on Length-Weight Relationships for
Seven Elasmobranch Species from North Aegean Sea, Turkey. E.Ü. Su Ürünleri
Dergisi 19(3-4), 401-409.
FILIZ, H., TOĞULGA, M., 2002. Türkiye Denizlerindeki Ekonomik Elasmobranş
Türleri, Balıkçılığı ve Yönetimi. Türkiyenin Kıyı ve Deniz Alanları IV. Ulusal
Konferansı 5-8 Kasım 2002, İzmir, pp 717-727.
FRISK, G.M., MILLER, T.J., FOGARTY, M.J., 2001. Estimation and Analysis of
Biological Parameters in Elasmobranch Fishes: A Comparative Life History Study.
Can. J. Fis. Aqu. Sci. 58 (5), 969-981.
FROESE, R., PAULY, D., 2004. Fishbase World Wide Web Electronic Publication.
www. fisbase. org. version (08/2004).
GUCU, A.C., BINGEL, F., 1994. Trawlable Species Assemblages on the Continental
Shelf of the Northeastern Levant Sea (Mediterranean) with an Emphasis on
Lesseptian Migration. Acta Adriat. 35 (1/2), 83-100.
HAMLETT, W.C., 1999. Sharks, Skates, and Rays. The Biology of the Elasmobranch
Fishes. The John Hopkins Univ. Press, Baltimore and London, pp 516.
HOLDEN, M.J., 1977. Elasmobranchs. In: J.A. GULLAND (ed), Fish Population
Dynamics, John Willey and Sons, New York, pp 187-215.
40
HOLDEN, M.J., RAITT. D. F. S., (eds) 1974. Manual of Fisheries Science. Part 2Methods of Resource Investigation and their Application. FAO Fish. Tech. Pap.
(115). Rev. 1, pp 214.
ISMEN, A., 2002. Age, Growth, Reproduction and Food of Common Stringray
(Dasyatis pastinaca L., 1758) in İskenderun Bay, the Eastern Mediterranean.
Fisheries Research 1403, 1-8.
KABASAKAL, H., 1994. Kıkırdaklı Balıkların (Gnathostomata: Chondrichthyes:
Elasmobranchii) Yaş tayininde Kullanılan Omurların Büyüme Çizgilerini
Belirginleştirmek İçin Teknikler. İstanbul Üniversitesi Su Ürünleri Dergisi 1-2, 145157.
MATER, S., KAYA, M., BILECENOGLU., 2003. Türkiye Deniz Balıkları Atlası. Ege
Üni. Su Ürünleri Fakültesi Yayınları No:68 Yardımcı Ders Kitapları, Dizin No:11,
Bornova-İzmir, pp 169.
NOTTAGE, A.S., PERKINS, E.J., 1980. Observations on the General Biology of the
Thornback Ray (Raja clavata L.) in the Solway Firth. 2. Cumbria Sea Fisheries.
Comm. Sci. Rep. 80/4.
OZYURT, C.E., 2003. The Determination of Mesh Size for Some Commercially
Important Demersal Fish Species Captured By Deep Trawl Net at Babadıllimanı
Bight (Silifke-Mersin). Çukurova Üni. Science Enst., Ph.D. Thesis, Adana, pp 124 (in
Turkish).
RICHARD, A., DAVIS, J.R., 1972. Principles of Oceanography. Addison-Wesley
Publishing Company, Philippines, pp 434.
WHEELER, A., 1969. The Fishes of British Isles and North Western Europe. Michigan
State University Pres, Michigan, pp 530.
WHITEHEAD, P.J.P., BAUCHOT, M.-L., HUREAU, J.-C., NİELSEN, J.,
TORTONESE, E., 1986. Fishes of the North-eastern Atlantic and the Mediterranean,
Vol. 1. Richard Clay Ltd, U.K., pp 510.
41
Proc. of the Int. Workshop on Med. Cartilaginous Fish with Emphasis on South.- East. Med., 14-16 Oct. 06, Istanbul-Turkey
SAVE THE SANDBAR SHARKS OF BONCUK BAY, TURKEY
Bayram ÖZTÜRK
Faculty of Fisheries, Istanbul University
Turkish Marine Research Foundation
Istanbul, Turkey
Abstract
Sandbar shark Carcharhinus plumbeus (Nardo, 1827) is found in Boncuk Bay,
Marmaris, on the southern Aegean coast of Turkey. The present study shows that this
bay is one of the critical habitats for this species and at least 2 nm (nautical miles) areas
should be protected for this vulnerable species in the Mediterranean Sea. Fisheries and
other anthropogenic factors should also be eliminated in the bay using the fisheries law
1380 to protect this species. Total of 23 fish species, 21 invertebrate species, and 4
marine mammal species were identified in Boncuk Bay.
Key words: Carcharhinus plumbeus, Aegean Sea, critical habitat.
Introduction
The sandbar shark Carcharhinus plumbeus (Nardo, 1827) is a large, slow growing and
low fecundity coastal species (Fig. 1). It occurs in offshore and inshore waters in
subtropical and warm temperate regions in world wide. It is found commonly in
continental shelf areas, shallow sandy or muddy bottoms in bays, or harbours, river
mouths, although it is found very rarely on sandy beaches and in the surface zone, coral
reefs and rough bottom, and the surface (COMPAGNO, 1984). Their long migration
cycle along the Western North Adriatic is well known. It migrates to south for winter
and north for summer. Main causes of these migrations are seasonal temperate changes,
current patterns, and local upwellings. Sandbar sharks prefer temperate waters in
shallow bays and estuaries as a nursery area of the east-central USA in the Western
North Atlantic (COMPAGNO, 1984). Atlantic population of the sandbar sharks was
over exploited, and this population declined very sharply in the last few decades (10-15
% survives) (URL1). Today, this species is very rare, and the IUCN Red List classifies
sandbar sharks as Lower Risk/Near Threatened at the world level (SHARK
SPECIALIST GROUP, 2000)
Data on sandbar sharks in the Mediterranean are very few. Nowadays, this
species is captured rarely in the Mediterranean. Boncuk Bay is the only known nursery
area in the Turkish coast in the Mediterranean (URL1; URL2; CLO and SABATA,
42
2004). This bay has been known as a nursery area of the sandbar shark at least since
1990.
CLO and SABATA (2004) stated that dozens sandbar sharks come in this bay
for reproduction every year in early summer (May and June). They have identified over
100 individuals in Boncuk Bay since 2001. They observed that mature females are
majority of the population in this bay (URL1, CLO and SABATA, 2004).
The aim of this paper is to describe the marine fauna of Boncuk Bay, and to
provide scientific data to the relevant authorities in case of the protection of Boncuk
Bay as a critical habitat for the sandbar shark.
Figure 1. Carcharhinus plumbeus
Materials and Methods
Boncuk Bay is located in Gökova Gulf, just next to the Sedir Island (Fig. 2). The bay is
situated in Marmaris, which is one of the resort areas of Turkey.
All the investigation were carried out with scuba diving and snorkelling in
early summer (May, June and July, 2003 and 2004). Fish, invertebrates and mammals
were identified visually at depth range 0-10 m.
43
Figure 2. Boncuk Bay
Results and Discussion
Total 21 invertebrate species belonging to 20 families were identified. Among them, 8
sponge, 3 coelenterate, 3 crustacean, 2 mollusc, 5 echinoderm species were determined.
List of the invertebrates in the bay is shown in Table 1.
Table 1. List of the invertebrate species observed in Boncuk Bay, Marmaris.
Phylum
Porifera
Famillies
Agelasidae
Aplysinidae
Axinellidae
Spongiidae
Irciniidae
Petrosiidae
Chondrillidae
Cnidaria
Annelida
Actiniidae
Serpulidae
Amphinomidae
Squillidae
Arthropoda
Species
Agelas oroides (Schmidt, 1864)
Aplysina aerophoba Nardo, 1843
Axinella verrucosa (Esper, 1794)
Hippospongia communis (Lamarck, 1814)
Sarcotragus muscarum Schmidt, 1862
Petrosia ficiformis (Poiret, 1798)
Chondrilla nucula Schmidt, 1862
Chondrosia reniformis Nardo, 1847
Actinia equina (Linnaeus, 1758)
Protula tubularia (Montagu, 1803)
Hermodice carunculata (Pallas, 1776)
Squilla mantis (Linnaeus, 1758)
44
Table 1. (Cont.)
Mollusca
Echinodermata
Penaeidae
Scyllaridae
Patellidae
Pinnidae
Echinasteridae
Echinidae
Toxopneustidae
Holothuriidae
Synaptidae
Melicertus kerathurus (Forskål, 1775)
Scyllarides latus (Latreille, 1803)
Patella caerulea Linné, 1758
Pinna nobilis Linné, 1758
Echinaster (Echinaster) sepositus (Retzius, 1783)
Paracentrotus lividus (de Lamarck, 1816)
Sphaerechinus granularis (de Lamarck, 1816)
Holothuria (Platyperona) sanctori Delle Chiaje, 1823
Synaptula reciprocans (Forskal, 1775)
Total 23 fish species belonging to 14 families were determined in Boncuk Bay
(Table 2). The species number was the highest to the family Sparidae. Sardina
pilchardus, Dicentrarchus Labrax, Mugil cephalus, Mullus surmuletus, Epinephelus
costea, Diplodus vulgaris, D. puntazzo, Oblada melanura, Boops boops, Sarpa salpa
and Scorpaena porcus are economically important species.
Table 2. List of the fish species observed in Boncuk Bay, Marmaris.
Families
Carcharhinidae
Atherinidae
Clupeidae
Congridae
Holocentridae
Labridae
Moranidae
Mugilidae
Mullidae
Muraenidae
Pomacentridae
Scorpaenidae
Serranidae
Sparidae
Species
Carcharhinus plumbeus (Nardo, 1827)
Atherina sp.
Sardina pilchardus (Walbaum, 1792)
Conger conger Linnaeus, 1758
Sargocentron rubrum (Forsskål, 1775)
Coris julis (Linnaeus, 1758)
Thalassoma pavo (Linnaeus, 1758)
Dicentrarchus labrax (Linnaeus, 1758)
Mugil cephalus Linnaeus, 1758
Mullus surmuletus Linnaeus, 1758
Mureana helena Linnaeus, 1758
Chromis chromis (Linnaeus, 1758)
Scorpaena porcus Linnaeus, 1758
Epinephelus costae (Steindachner, 1878)
Serranus scriba (Linnaeus, 1758)
Boops boops (Linnaeus, 1758)
Diplodus annularis (Linnaeus, 1758)
Diplodus puntazzo (Cetti, 1777)
Diplodus vulgaris (E. Geoffrey Saint-Hilaire, 1817)
Oblada melanura (Linnaeus, 1758)
Sparus aurata Linnaeus, 1758
Salpa salpa (Linnaeus, 1758)
45
As marine mammals, Delphinus delphis (Linnaeus, 1758), Stenella
coeruleoalba (Meyer, 1833), Tursiops truncatus (Montagu, 1821) and Monachus
monachus Hermann 1779 were observed in Boncuk Bay.
Total 23 fish species, 21 invertebrates and 4 marine mammals were determined
in Boncuk Bay. Among them Sargocentron rubrum and Synaptula reciprocens were
exotic species originally from the Red Sea.
During this study, C. plumbeus was observed very frequently in May and June.
Maximum number of individuals observed at a time was 11, but generally 1 or 2
individuals are seen at a time, rarely exceeding 4. This species preferred mostly 3-5 m
depths in the bay in early summer. The sandbar shark had been known to occur there at
least in the last three decades by divers, fishermen and local boat owners. Over 100
sandbar shark individuals have been identified in this bay since 2001 by CLO and
SABATA (2004). Also, the same authors recorded the birth of a shark in 2004 in the
same area (CLO and SABATA, 2004). This is an evident that this bay is a nursery area
for sandbar sharks in the Mediterranean.
Conclusions
1. Boncuk Bay is one of the most quiet resort areas in Gökova Gulf. Relatively
small tourism activity and being next to the Sedir Island, which is protected due to its
famous Cleopatra beach, are advantages for the habitat protection, but the tourism
activities can be a threat in the future.
2. Purse seining, long lining, gill netting are main fisheries activities in the bay,
except for August. Massive fishing activities are the main threat for the sandbar shark
population in the bay.
Boncuk Bay is the only known nursery area for the sandbar shark
Carcharhinus plumbeus in the Mediterranean Sea. This area, threfore, should be
protected for the survival of the sandbar shark population.
It is not known where these fish migrate for the rest of the year since this
species is observed in the bay mostly in May and June, and very rarely in July. A
monitoring study by tagging should be performed to understand their movement.
Besides, the sandbar shark has also been observed in Mandalya Bay in 1990 and a
detailed study is also needed for some other areas.
References
CLO, S., DE SABATA, E., 2004. In the sharks’ cradle. 8th European Elasmobranch
Association Conference, 21st-24th October 2004, Zoology Society of London.
COMPAGNO, L. J. V., 1984. FAO species catalogue. Vol. 4. Sharks of the world. An
annotated and illustrated catalogue of shark species known to date. FAO Fish. Synop.
No. 125, Vol. 4.
46
SHARK SPECIALIST GROUP, 2000. Carcharhinus plumbeus. In: IUCN 2004. 2004
IUCN Red List of Threatened Species. <www.iucnredlist.org>. Downloaded on 28
March 2006.
URL1, http://xoomer.virgilio.it/medsharks/ricerca_eng.htm
URL2, http://www.sea-stories.net/turchia2003eng.html
47
Proc. of the Int. Workshop on Med. Cartilaginous Fish with Emphasis on South.- East. Med., 14-16 Oct. 06, Istanbul-Turkey
SEXUAL DIMORPHISM IN THE HEAD, MOUTH AND BODY
MORPHOLOGY OF THE LESSER-SPOTTED DOGFISH,
Scyliorhinus canicula, FROM TURKEY
Halit FİLİZ and Ertan TAŞKAVAK
Ege University, Faculty of Fisheries, Department of Basic Sciences, 35100 Bornova/ Izmir, Turkey
E-mail: ertan.taskavak@ege.edu.tr
Abstract
Males of Scyliorhinus canicula have a longer and narrower mouth than females
resulting in pronounced sexual dimorphism with respect to the mouth length/mouth
width ratio (0.55 and 0.50, respectively). Significant sexual differences related to head
measurements (i.e., snout to spiracle and snout to pectoral) were recorded. Some body
measurements, i.e. pelvic to anal, pectoral inner edge, pelvic to median tip and upper
caudal as well as total body length differentiated males from females. Reasons for these
differences are discussed.
Key words: Scyliorhinus canicula, Elasmobranchii, sexual dimorphism, meristic.
Introduction
The lesser spotted dogfish, Scyliorhinus canicula Linnaeus, 1758(Family:
Scyliorhinidae), is an Atlanto-Mediterranean demersal species, inhabiting continental
shelves and uppermost slopes, found on sandy, coralline, algal, gravel or muddy
bottoms between 3-400 meters depth (HUREAU and MONOD, 1973; CAPAPE, 1977;
JARDAS, 1979; WHITEHEAD et al., 1984; FROESE and PAULY, 2004). The species
is common in the Mediterranean (CAPAPE, 1977; JARDAS, 1979; CIHANGIR et al.,
1997; BERTRAND et al., 2000; BAINO and SERENA, 2000) and widespread in the
Northeast Atlantic (WHITEHEAD et al., 1984).
Differences in the selective pressures experienced by the sexes can ultimately
result in the evolution of sexual dimorphism of morphological traits (CASSELMAN
and SCHULTE-HOSTEDDE, 2004). Sexual dimorphism with respect to body size
appears more common among shark species where females have viviparous and
ovoviviparous reproductive modes (SIMS, 2003). ELLIS and SHACKLEY (1995) and
ERDOGAN et al. (2004), however, have demonstrated that sexual dimorphism can
occur in oviparous sharks as S. canicula.
Morphological and dental differences are two useful criteria for the taxonomy of
elasmobranch fish (ELLIS and SHACKLEY, 1995). However, intraspecific variation,
due to growth, sexual dimorphism and geographical and individual differences, has
been little studied (STEFFENS and D'AUBREY, 1967; TANIUCHI, 1970;
48
BASS, 1973; SIQUEIROS-BELTRONES, l990; KAJIURA and TRICAS, 1996;
KAJIURA, 2001).
BROUGH (1937) noted that the head and mouth were narrower and the
intermandibular separation less in male S. canicula. He correlated changes in the lower
jaw structure to sexual maturity and observed that these sexual dimorphic characters
were more pronounced in the breeding season and were not present in sexually
immature specimens. Sexual dimorphism in the mouth length/mouth width ratio of S.
canicula has also been described briefly (ARTHUR, 1950). It is considered that this
sexual dimorphism occurs relatively suddenly at the onset of maturity (BROUGH,
1937). Morphometric studies of S. canicula from the Mediterranean have shown
negative allometric growth of the head (BAS, 1964), and JARDAS (1979) and
ERDOGAN et al. (2004) reported that males had longer heads than females.
The purpose of the present study was to determine the extent of sexual
variation in the head morphometrics of S. canicula and to assess its possible functional
significance.
Materials and Methods
On September and November 2002, we collected the specimens from Foca Trawl Area
(Izmir Bay, Aegean Sea, Turkey) in depths between 40 and 120 meters, with two
bottom trawls materialized by commercial vessel (Fig. 1). A total of 296 Scyliorhinus
canicula specimens were sampled. The sex, total length (TL), mouth length (MoL) and
mouth width (MoW) of 123 females and 173 males were recorded to the nearest mm.
For analyses, we followed the methodology described by ELLIS and SHACKLEY
(1995). Significant differences of the mouth length (%TL), mouth width (%TL) and
mouth length/mouth width ratio (MoL/MoW) between the sexes were calculated from a
t-test of the differences between two means (SOKHAL and ROHLF, 1981). The data
were further divided into six TL groups (<275, 275-324, 325-374, 375-424, 425-474
and >475 mm) with similar tests used to determine any significance between the various
TL groups within each sex, and between the same TL groups of each sex.
Eight morphometric measurements of the head region and eighteen
morphometric measurements of the body (according to BASS et al., 1975) were also
examined to determine the differences between sexes (Fig. 2). These dimensions were
measured to the nearest mm and converted to % TL for statistical analysis.
Results
Males possessed a significantly longer (4.02 and 3.75 % respectively; P<0.000l) and
narrower mouth (7.42 and 7.51 % respectively; P<0.0001) than females (Table 1).
These differences result in a significant sexual dimorphism with respect to MoL/MoW
(0.55 and 0.50 for males and females respectively; P<0.000l). MoL/MoW was almost
constant in the length groups 1, 2 and 3, and decreased significantly after the length
group 4, whereas this ratio increased significantly with length in male fish (Fig. 3).
49
Comparing the sexual differences in these measurements for each size group
(Table 2) indicated that sexual dimorphism occurred only in the TL groups larger than
374 mm. Other size groups smaller than 375 mm showed no significant differences. For
fish 375-424 mm, although MoL was found to be significantly different, MoW and
MoL/MoW were not significantly different. For fish 425-474, MoL and MoL/MoW
were significantly differentiated between sexes. All fish larger than 475 mm groups
showed significant differences for all three variables.
Figure 1. Localities where the Scyliorhinus canicula specimens were sampled.
Significant size-based differences were observed for both sexes, although more
so for male fish. MoL/MoW in males increased from 0.49 (<275 mm TL) to 0.61 (>475
mm TL) (Table 1) with significant differences occurring between fish smaller than
275mm TL and the three larger size groups (375-424, 425-475 and >475 mm;
P=0.0005, 0.0004 and 0.0001, respectively). This difference in MoL/MoW can be
attributed to an increase in the MoL and a relative decrease in MoW as male fish grew.
MoL of fish <275, 275-324 and 325-374 mm were significantly different from three of
the larger TL groups (P<0.005 for all). Significant differences in MoW occurred
between fish <275 mm and the other five TL groups (P<0.005 for all). MoL and MoW
changed very little in female fish (Table 2).
Both MoL and MoW were positively correlated with TL in males and females
(Fig. 4). The linear relationships are described by the following equations;
Females:
MoL= 0.035 T.L + 0.738 (r2 = 71.99, n = 123)
MoW= 0.074 T.L + 0.452 (r2 = 79.26, n = 123)
Males:
MoL= 0.047 T.L – 2.505 (r2 = 76.99, n = 173)
MoW= 0.060 T.L + 5.174 (r2 = 79.26, n = 173)
50
Figure 2. Measurements taken in the present study. Aa: snout to nostrils; Ab: snout to mouth; Ac: snout to
eye; Ad: snout to first gill-slit; Ae: snout to pectoral; Af: snout to first dorsal; Ag: snout to pelvic;
Ah: standard length (snout to upper caudal); As: snout to spiracle; B: eye diameter; D: first to
second dorsa; E: between dorsal bases; F: pectoral to pelvic; G: pelvic to anal; H: second dorsal to
upper caudal; I: anal to lower caudal; MoL: mouth length; MoW: mouth width; Na: pectoral base;
Nb: pectoral inner edge; Nc: pectoral length; Oa: pelvic to lateral lobe; Ob: pelvic to median tip;
Pa: upper caudal; Pc: lower caudal; S: spiracle length (According to Bass et al., 1975).
Distances from snout to spiracle and from snout to pectoral were significantly
different between males and females (P=0.037 and 0.026, respectively, Table 3). Males
have longer snout to spiracle and snout to pectoral lengths than those of females. Snout
to first gill-slit length tended to be shorter in female fish, although these measurements
were not statistically significant (P=0.057). Similarly, when we also compared the
51
measurements take from other parts of the body, except for head region, a set of five
characters (total body length, pelvic to anal, pectoral inner edge, pelvic to median tip
and upper caudal) differentiated males from females (Table 4).
A
B
Figure 3. Graphs showing the relationship between mean MoL/MoW (± Standard deviation) and
size group in (A) female and (B) male Scyliorhinus canicula (1: <275, 2: 275-324, 3:
325-374, 4: 375-424, 5: 425-474 and 6: >475).
A
B
Figure 4. Graphs showing the linear relationships between mouth width and total length, and
mouth length and total length for male (A) and female (B) Scyliorhinus canicula.
52
Table 1. Differences for male and female Scyliorhinus canicula specimens in mouth morphometries by TL (Values given are the mean r SD and range
in parenthesis).
MALES
FEMALES
53
TL
N
MoL/MoW
MoL (%)
MoW(%)
N
MoL/MoW
MoL(%)
MoW(%)
<275
15
0.49r0.12
[0.25-0.74]
3.85r0.59
[3.11-5.60]
8.16r1.91
[5.83-14.20]
16
0.49r0.07
[0.38-0.63]
3.69r0.42
[2.78-4.48]
7.60r1.11
[4.63-9.85]
275-324
26
0.51r0.07
[0.34-0.65]
3.81r0.39
[2.97-4.55]
7.50r0.57
[6.67-9.02]
29
0.51r0.09
[0.36-0.85]
3.84r0.69
[2.67-5.97]
7.59r0.73
[5.87-9.09]
325-374
35
0.51r0.06
[0.40-0.65]
3.84r0.37
[3.22-4.86]
7.51r0.59
[5.48-8.49]
28
0.51r0.07
[0.36-0.70]
3.75r0.38
[3.06-4.51
7.51r0.83
[5.03-8.82]
375-424
30
0.57r0.11
[0.32-0.90]
4.19r0.65
[3.21-6.31]
7.50r1.12
[5.98-12.59]
21
0.53r0.05
[0.44-0.67]
3.85r0.38
[3.05-4.45]
7.25r0.76
[5.94-8.32]
425-474
46
0.57r0.06
[0.44-0.84]
4.17r0.48
[3.32-6.24]
7.30r0.49
[6.28-8.94]
20
0.50r0.05
[0.39-0.63]
3.68r0.38
[3.12-4.42]
7.42r0.64
[6.17-8.37]
>475
21
0.61r0.07
[0.49-0.77]
4.12r0.32
[3.59-4.84]
6.80r0.65
[5.46-7.80]
9
0.46r0.05
[0.41-0.55]
3.59r0.37
[3.04-4.17]
7.85r0.48
[6.84-8.42]
¦
173
0.55r0.09
[0.25-0.90]
4.02r0.50
[2.97-6.31]
7.42r0.92
[5.46-14.20]
123
0.50r0.07
[0.36-0.85]
3.75r0.47
[2.67-5.97]
7.51r0.79
[4.63-9.85]
Table 2. Probability values showing the statistical differences of MoL/MoW, MoL%
and MoW% (using t-test) between males and females of entire Scyliorhinus
canicula specimens.
MoL/MoW
0.975
<275
0.850
275-324
0.573
325-374
0.175
375-424
0.000*
425-474
0.000*
>475
0.000*
∑
(* indicates significant differences)
MoL%
0.382
0.880
0.317
0.033*
0.001*
0.000*
0.000*
MoW%
0.317
0.628
0.992
0.374
0.403
0.001*
0.417
Table 3. Descriptive statistic of eight metric measurements of the head region of males
(n=173) and females (n=123) (Values given are the mean ± SD and range in
parenthesis).
Male
Mean±SD
2.44±0.39
Snout to nostrils (Aa)
[1.79-3.73]
3.91±0.37
Snout to mouth (Ab)
[2.33-5.48]
5.68±0.50
Snout to eye (Ac)
[3.15-7.80]
9.50±0.55
Snout to spiracle (As)
[7.22-13.40]
12.48±0.89
Snout to first gill-slit (Ad)
[10.17-18.40]
16.55±1.47
Snout to pectoral (Ae)
[7.39-24.00]
3.68±0.75
Eye diameter (B)
[0.96-6.58]
0.85±0.15
Spiracle length (S)
[0.53-1.40]
(* indicates significant differences)
Measurements
54
Female
Mean±SD
2.46±0.40
[1.70-4.71]
3.96±0.37
[2.54-5.16]
5.60±0.56
[3.28-7.19]
9.33±0.83
[3.92-11.11]
12.25±1.18
[9.94-21.82]
16.20±1.13
[13.70-20.06]
3.65±0.65
[2.18-5.24]
0.84±0.17
[0.42-1.48]
P
0.653
0.298
0.113
0.037*
0.057
0.026*
0.744
0.824
Table 4. Descriptive statistic of eighteen metric measurements of the body of males
(n=173) and females (n=123) (Values given are the mean ± SD and range in
parenthesis).
Measurements
Total Length (TL)
Snout to first dorsal (Af)
Snout to pelvic (Ag)
Standard length (Ah)
Snout to lower caudal lope (Aj)
First to second dorsal (D)
Between dorsal bases (E)
Pectoral to pelvic (F)
Pelvic to anal (G)
Second dorsal to upper caudal (H)
Anal to lower caudal (I)
Pectoral base (Na)
Pectoral inner edge (Nb)
Pectoral length (Nc)
Pelvic to lateral lobe (Oa)
Pelvic to median tip (Ob)
Upper caudal (Pa)
Lower caudal (Pc)
MALE
Mean±SD
385.83±73.70
[210.00-525.00
49.51±2.14
[45.46-70.00]
39.29±2.08
[27.65-56.00]
79.90±3.64
[68.66-114.00]
78.06±3.03
[68.00-110.00]
18.20±1.19
[15.09-26.80]
12.78±1.05
[10.50-19.20]
23.54±1.73
[18.52-36.00]
19.30±1.27
[16.67-26.00]
12.44±1.02
[10.19-16.80]
20.17±1.25
[16.67-29.20]
5.20±0.60
[3.88-8.00]
5.95±0.71
[4.00-8.22]
12.13±0.98
[9.33-15.71]
5.97±0.64
[4.27-8.40]
12.63±1.23
[9.43-17.20]
20.49±1.43
[16.81-28.00]
9.32±1.29
[4.67-14.80]
(* indicates significant differences)
55
FEMALE
Mean±SD
357.89±72.59
[210.00-508.00]
49.32±3.10
[45.20-76.27]
39.81±3.02
[35.00-58.68]
79.54±2.02
[76.09-93.14]
77.98±3.22
[72.36-102.63]
18.14±1.01
[14.88-21.57]
12.90±0.99
[10.79-17.11]
23.79±1.46
[20.00-27.78]
18.91±1.42
[15.24-23.26]
12.62±1.26
[9.36-16.67]
20.26±1.24
[17.05-24.00]
5.24±0.59
[3.68-7.46]
6.18±0.80
[4.32-9.47]
12.19±0.84
[10.29-15.03]
5.97±0.61
[4.14-8.37]
10.76±0.81
[8.24-12.67]
21.11±2.06
[17.78-34.72]
9.39±1.15
[4.12-11.63]
P
0.001*
0.533
0.083
0.311
0.820
0.648
0.338
0.193
0.013*
0.176
0.576
0.571
0.008*
0.576
0.966
0.000*
0.003*
0.619
Discussion
Sexual dimorphism with respect to body size appears more common among shark
species where females have viviparous and ovoviviparous reproductive modes (SIMS,
2003). Although S. canicula is a oviparous shark species, previous studies (BROUGH,
1937; ARTHUR, 1950; BAS, 1964; JARDAS, 1979; ELLIS and SHACKLEY, 1995;
ERDOGAN et al., 2004) have shown that this kind of dimorphism can occur in the
lesser spotted dogfish and our findings support previous ones.
The MoL/MoW values of 0.55 and 0.50 (males and females, respectively)
calculated for the present study coincide with the values (0.59 and 0.53 for males and
females, respectively) given by ARTHUR (1950) and (0.67 and 0.57 for males and
females, respectively) reported by ERDOGAN et al. (2004) for S. canicula, thus this
sexual dimorphism in MoL/MoW has been confirmed statistically in the present study.
However, although these values correspond to the upper limit of the ranges recorded,
those values given by ARTHUR (1950) and ERDOGAN et al (2004) were significantly
different to the mean values of 0.49 and 0.43 calculated by ELLIS and SHACKLEY
(1995). ELLIS and SHACKLEY (1997) claimed that that might be because ARTHUR
(1950) had used a small sample size. However, sample size used in the present study is
bigger than that used by ELLIS and SHACKLEY (1995). This sexual dimorphism in
MoL/MoW was due to an increase in %MoL and decrease in %MoW of male fish.
Changes in mouth morphology, if correlated with reproductive changes, may be
considered as secondary sexual characteristics (ELLIS and SHACKLEY, 1995). In the
present study, MoL/MoW was significantly different between sexes for only the larger
size groups and not for those fish <375 mm (Table 2). Differences in intermandibular
separation have been related previously to sexual maturity (BROUGH, 1937). FORD
(1921) computed that both sexes of S. canicula attained maturity at 57-60 cm. However,
more recent data suggest that males and females mature at lengths of approximately 52
and 55cm respectively (ELLIS and SHACKLEY, 1997; maturity assessed by clasper
length, nidamental gland width and weight and appearance of gonads). ELLIS and
SHACKLEY (1995) considered that the changes in mouth morphology of male fish and
the subsequent sexual dimorphism in MoL/MoW was related to sexual maturity, as
those fish <500 mm were immature, 500-549 mm maturing and fish within the larger
size groups were mature. GOSZTONYI (1973) studied sexual dimorphism in the mouth
shape of Schroederichthys bivius (Smith) and determined that the MoL/MoW was 0.50
in females and juvenile males and 0.80 in mature males.
MoL and MoW were both positively correlated with TL in both sexes (Fig. 4),
however, the present study lacks information on specimens below 210mm (size group
<275) and above 525 (size group >475). BASS (1973), who studies on the relationship
between MoL and TL, reported an initial decrease and subsequent increase in MoL for
larger fish in a sample of 119 male and female Carcharhinus leucas. ELLIS and
SHACKLEY (1995) suggested that that initial decrease in MoL after birth was probably
due to the head region being better developed in proportion to the rest of the body at
birth.
56
According to ELLIS and SHACKLEY (1995), possible explanations as to why
the mouth dimensions in male S. canicula change during maturation, and fact that males
have longer teeth than females, included differential feeding habits and adaptations for
reproductive behavior. The diet of S. canicula is composed primarily of decapod
crustaceans, molluscs and teleosts (FORD, 1921; LYLE, 1983). LYLE (1983) found no
significant sexual difference in the diet of S. canicula in Isle of Man waters. Both
precopulatory behavior and copulation in scyliorhinids may involve the male biting the
fins and body of the female (CASTRO et al., 1988) and so the mouth of the male may
have adapted for this function by changes in shape and dentition (ELLIS and
SHACKLEY, 1995).
We could not determine any statistical difference between pre-oral lengths
(snout to mouth in Table 3; P= 0.298) of male and female S. canicula specimens.
However, ELLIS and SHACKLEY (1995) and ERDOGAN et al. (2004) found that preoral length was significantly shorter in males and they claimed that it was a probable
result of the increased mouth length. Similarly, they claimed that the significant
differences in the measurements of pre-branchial length, head length and head girth
might be contributed to sexual differences in the pattern of growth of the whole head
region. Our finding on the measurement of snout to spiracle almost coincides with the
result given by ELLIS and SHACKLEY (1995). Although no statistical difference was
computed between pre-branchial lengths of male and female, the distance from snout to
fist gill-slit was relatively longer in males (P= 0.057). We also found that the distance
snout to pectoral was longer in males than this in females.
Regarding body measurements, except for head, the distances from pelvic to
anal and pelvic to median tip were longer in males than those in females, whereas,
lengths of pectoral inner edge and upper caudal were shorter in males. ELLIS and
SHACKLEY (1995) recorded total body length of 586 and 555 mm for males and
females respectively, and this sexual dimorphism in total body length has been
confirmed in our study. However, the mean values given by ELLIS and SHACKLEY
(1995) for male and female S. canicula are significantly different to the mean values of
385 and 357 mm calculated for the present study. It is obvious that Aegean population
of S. canicula is much smaller than those collected from Swansea and Oxwich Bays in
the Bristol Channel and from the Irish Sea. By taking into consideration length range
and sexual maturity length, CIHANGIR et al. (1997), who studied some biological
characteristics and distribution of S. canicula from North Aegean Sea, claimed that
growth of Mediterranean dogfish is slower than Atlantic ones, and they reach sexual
maturity in relatively smaller length than those from Atlantic. LITVINOV (2003), who
studied sexual dimorphism as an index of the isolation of West African populations of
S. canicula, noted significant morphological differences between West African cat
sharks and West European and Mediterranean cat sharks against the background of
spatial disintegration and isolation. According to him, comparative morphological
studies on West African, West European, and Mediterranean sharks are needed to solve
the issue of distinguishing West African cat shark as an independent species or
subspecies.
57
Acknowledgments
No data could have been collected without helps and cooperation of fishermen who
allowed us to their ships and Harun Güclüsoy from Underwater Research Society,
Mediterranean Monk Seal Research Group (SAD-AFAG). We are grateful to F.F.
Litvinov, C. Rodriguez-Cabello, F. Sánchez, J-Y. Sire and C. Capape. Who kindly made
comments on an early version of the manuscript.
References
ARTHUR, D. R., 1950. Abnormalities in the sexual apparatus of the common dogfish
(Scyliorhinus canicula). Proceedings of the Linnean Society of London 162, 52-56.
BAINO, R. and F. SERENA. 2000. Valutazione di abbondanza e distribuzione
geografica di alcuni Selaci dell’alto Tirreno e Mar Ligure Meridionale. Biol. Mar.
Medit. 7(1), 433-439.
BAS, C., 1964. Aspectos del crecimiento relativo de Scylliorhinus canicula.
Investigacion Pesquera 27, 3-12.
BASS, A. J., 1973. Analysis and description of variation in the proportional dimensions
of Scyliorhinid, Carcharhinid and Sphyrnid sharks. South African Association of
Marine Biological Research, Oceanographic Research Institute (Durban)
Investigational Report 32, pp 28.
BASS, A.J., D’AUBREY, J.D., KISTNASAMY, N., 1975. Sharks of the east coast of
southern Africa. III. The families Carcharhinidae (excluding Mustelus and
Carcharhinus) and Sphyrnidae. South Africa Assc. For Mar. Biol. Res., Ocea. Res.
Inst., Investigotional Report No:38, Durban, S. Africa, pp100.
BERTRAND, J., GIL DE SOLA, L., PAPAKONSTANTINOU, C., RELINI, G.,
SOUPLET, A., 2000. Contribution on the distribution of elasmobranchs in the
Mediterranean (From the Medits Surveys). Biol. Mar. Medit. 7(1), 385-399.
BROUGH, J., 1937. On certain secondary sexual characters in the common dogfish
(Scyliorhinus canicula). Proceedings of the Zoological Society of London 107, 217223.
CAPAPE, C., 1977. Contribution à la biologie des Scyliorhinidae des cŏtes tunisiennes
Scyliorhinus canicula (L., 1758) Répartition géographique et bathymétrique,
sexualité, reproduction, fécondité. Bull. Off. Natn. Péch. Tunisie 1(1), 83-101.
CASSELMAN, S. J., SCHULTE-HOSTEDDE, A. I., 2004. Reproductive roles predict
sexual dimorphism in internal and external morphology of lake whitefish, Coregonus
clupeaformis. Ecology of Freshwater Fish 13, 217-222.
CASTRO, J. I., BUBUCIS, P. M., OVERSTROM, N. A., 1988. The reproductive
biology of the chain dogfish, Scyliorhinzis retifer. Copeia 1988, 740-746.
CIHANGIR, B., UNLUOGLU, A., TIRASIN, E.M., 1997. Distribution and some
biological aspects of the lesser spotted dogfish (Chondrichthyes, Scyliorhinus
canicula, Linnaeus, 1758) from the northern Aegean Sea. Mediterranean Fisheries
Congress. 9-11 April 1997, pp 585-603.
58
ELLIS, J. R., SHACKLEY, S. E, 1995. Ontogenetic changes and sexual dimorphism in
the head, mouth and teeth of the lesser spotted dogfish. Journal of Fish Biology 47,
155-164.
ELLIS, J. R., SHACKLEY, S. E., 1997. The reproductive biology of Scyliorhinus
canicula in the Bristol Channel, U.K. J. Fish Biol. 51, 361-372.
ERDOGAN, Z. A., KOÇ, H. T., ÇAKIR, D. T., NERLOVIC, V., DULCIC, J., 2004.
Sexual dimorphism in the small-spotted catshark, Scyliorhinus canicula (L., 1758),
from the Edremit Bay (Turkey). Ser. Hist. Nat., 14 (2), 165169.
FORD, E., 1921. A contribution to our knowledge of the life histories of the dogfishes
landed at Plymouth. J. Mar. Biol. Ass. U. K. 12, 468-505.
FROESE, R., PAULY, D. (Ed.). 2004. Fishbase World Wide Web electronic
publications. www.fishbase.org, 20 Sept. 2004.
GOSZTONYI, A. E., 1973. Sobre el dimorfismo sexual secundano en Halaelurus bivius
(Muller y Henle 1841) Garman 1913 (Elasmobranchii, Scyliorhinidae) en aguas
PatagonicoFueguinas Physis Seccion A 32(85), 317-323.
HUREAU, J-C., MONOD, T., 1973. Check-list of the Fishes of the North-Eastern
Atlantic and Mediterranean (CLOFNAM I), Unesco, Paris, pp. 436.
JARDAS, I., 1979. Morphological, biological and ecological characteristics of the lesser
spotted dogfish, Scyliorhinus canicula (Linnaeus, 1758) population in the Adriatic
Sea. Institut za Oeeanografiju i Ribarstva-Split 4(2-3), 1-104.
KAJIURA, S. M., 2001. Head morphology and electrosensory pore distribution of
carcharhinid and sphyrnid sharks. Environmental Biology of Fishes 61, 125-133.
KAJIURA, S. M., TRICAS, T. C., 1996. Seasonal dynamics of dental sexual
dimorphism in the Atlantic stingray, Dasyatis sabina. Jour. Exp. Biol. 199, 22972306.
LITVINOV, F.F., 2003. Sexual dimorphism as an index of the isolation of West African
populations of the cat shark S. canicula. Journal of Ichthyology 43 (1), 81-85
LYLE, J. M., 1983. Food and feeding habits of the lesser spotted dogfish, Scyliorhinus
canicula (L.) in Isle of Man waters. J. Fish Biol. 23, 725-737.
SIMS, D. W., 2003. Tractable models for testing theories about natural strategies:
foraging behaviour and habitat selection of free-ranging sharks. J. Fish Biol. 63
(Suppl. A), 53-73.
SIQUEIROS-BELTRONES, D. A., 1990. Morphometric analysis of sharks of the genus
Carcharhinus Blainville, 1816: C. limbatus (Valenciennes, 1841) and C. brevipinna
(Müller & Henle, 1841) from Mexican waters. Scientia Marina 54, 349-358.
SOKHAL, R. R., ROHLF, F. J., (1981). Biometry. San Francisco, CA: Freeman.
STEFFENS, F. E., D'AUBREY, J. D., 1967. Regression analysis as an aid to shark
taxonomy. South African Association of Marine Biological Research, qeeana graphie
Research Institute (Durban), Investigational Report 18.
TANIUCHI, T., 1970. Variation in the teeth of the sand shark, Odontaspis taurus
(Rafinesque) taken from the East China Sea. Japan. J. Ichthyology 17, 37-44.
WHITEHEAD, P.J.P., M.L. BAUCHOT, J.C. HUREAU, J. NIELSEN, TORTONESE
E. (Eds)., 1984. Fishes of the North-eastern Atlantic and the Mediterranean. Unesco,
Paris, 1, pp. 510 .
59
Proc. of the Int. Workshop on Med. Cartilaginous Fish with Emphasis on South.- East. Med., 14-16 Oct. 06, Istanbul-Turkey
FOOD OF LESSER SPOTTED DOGFISH, Scyliorhinus canicula
(Linnaeus, 1758), IN FOCA (THE NORTHEAST AEGEAN SEA,
TURKEY) IN AUTUMN 2002
Halit FİLİZ and Ertan TAŞKAVAK
Ege University, Faculty of Fisheries, Department of Basic Sciences, 35100 Bornova/ Izmir, Turkey,
E-mail: halit.filiz@ege.edu.tr
Abstract
In the present study, stomach contents of 146 lesser-spotted dogfish, Scyliorhinus
canicula (78 male, 240-502 mm TL and 68 female, 215-508 mm TL), were examined.
Fish and crustaceans were found to be most important prey groups (MIP; IRI≥352, and
% IRI = 52.00 and % IRI = 42.07, respectively) in the diet. Polychaetes and
Cephalopods constituted the secondary prey groups (SP; 352>IRI>39; % IRI = 3.29 and
2.44, respectively). Sipunculida (% IRI = 0.20) were an occasional prey group (OP;
IRI≤39).
Key Words: Scyliorhinus canicula, feeding habits, stomach content, Aegean Sea.
Introduction
Sharks play an important role in aquatic food webs throughout their evolutionary history
(CORTES, 1999). While it is widely recognized that many extant species of sharks are
top or apex predators in marine communities, surprisingly little quantitative information
is available on their diets (CORTES, 1999). The feeding habits of sharks, in particular,
determine their role in the exchange of energy between upper trophic levels of the
marine environment (GELSLEICHTER et al., 1999).
The lesser-spotted dogfish are small bottom-living sharks which occur on a
wide variety of seabed types but are most commonly encountered on sand or gravel at
depths between 3 and 400 m (CAPAPE, 1977; JARDAS, 1979; FROESE and PAULY,
2003). The species is common in the Mediterranean (CAPAPE, 1977; JARDAS, 1979;
CIHANGIR et al., 1997) and widespread in the Northeast Atlantic (OLASO et al.,
2002; FROESE and PAULY, 2003).
Various studies about feeding of this species are available (ELLIS et al., 1996;
SIMS et al., 1996; OLASO et al., 1998; VELASCO et al., 2001; OLASO et al., 2002),
however, similar studies from Turkey’s coasts are scarce (etc., CIHANGIR et al., 1997;
KABASAKAL, 2001; 2002). Such information is necessary to understand the role that
this species plays in the trophic structure of coastal marine communities
(GELSLEICHTER et al., 1999). Thus, this study presents data on the food habits of
lesser
spotted
dogfish
from
the
Northeast
Aegean
Sea.
60
Materials and Methods
Data Collection
All specimens caught by bottom trawls were taken from commercial fishermen
in Foça (the Northeast Aegean Sea) (Fig. 1). Trawl surveys were carried out between
September and November 2002 in depths between 40 and 120 meters. A total of 296
Scyliorhinus canicula specimens were sampled. The fish were stored in ice until
returned to the laboratory, where the length and weight measurements were taken. Of
them, stomachs of 146 lesser spotted dogfish (78 male, 240-502 mm TL and 68 female,
215-508 mm TL) were chosen randomly. Stomachs of the individuals were excised
from the esophageal region. The stomach samples were fixed in a 250 cc polyethylene
container using 4% buffered formalin. A label contains information as date, locality and
number of sample was placed in each container. In order to determine stomach
condition, five categories were used; empty, full (F), ¼ F, ½ F, and Vomited. In order to
designate condition of stomach content, a scale proposed by ALBERT (1995) was
applied (Table 1). The items were carefully separated, weighed (nearest to the 0.01 g)
and identified to the possible lowest taxonomic level. The individuals of each identified
taxon were counted. Whenever fragments were found, the number of individuals was
taken as the smallest possible number of individuals from which fragments could have
originated.
Diet Analysis
Diet composition was evaluated using three measures described in HYSLOP
(1980): the numerical index (% N); the gravimetric index (% W), and frequency of
occurrence (% O). Each of these indices provides different insight into feeding habits of
a predator: numerical abundance is informative regarding feeding behaviour, volume or
weight indices reflect dietary nutritional value, and occurrence represents populationwide food habits (CORTES, 1997). One of the most widely used compound indices in
fish diet studies is the index of relative importance (IRI; PINKAS et al., 1971). In this
method, the percent frequency of occurrence of each prey category is multiplied by the
sum of the percentage volume (or weight) and percentage number [IRI = (% N+% W)x
% O]. By incorporating bulk, amount, and occurrence into a single measure it appears to
provide a more accurate description of dietary importance and is also intended to
facilitate comparative studies (CORTES, 1997). It is therefore suggested that IRI be
expressed on a percent basis (CORTES, 1997), such that %IRI for a specific food
category i (IRIi) becomes;
n
% IRIi = 100 IRIi / Σ IRIi
i=1
where n is the total number of food categories considered at a given taxonomic level.
61
Therefore, food items were grouped into categories of preference using the
method proposed by MORATO et al. (1998). The categories were measured according
to the equations:
IRI ≥ 30 x (0.15 x ∑%O)
- main important prey (MIP)
30 x (0.15 x ∑%O) > IRI > 10 x (0.05 x ∑%O)
- secondary prey (SP)
IRI ≤ 10 x (0.05 x ∑%O)
- occasional prey (OP)
Graphical representation of diet analysis has been used as an alternative to
summary tables and included measures mentioned above. CORTES (1997) proposed a
method, which uses %O, %N and %W (or %V) in a three-dimensional graphical
representation of population-level stomach content data. Each point on the graph
represents the percent occurrence and abundance (in weight or volume and numbers) for
a prey category (Fig. 2).
Figure 1. Study area.
62
Table 1. Definition of digestion status of prey (ALBERT, 1995)
Status
I
II
III
IV
V
VI
Definition
Fresh; prey without signs of digestion.
Digestion just started; prey intact except for the more delicate parts
Moderately digested; prey clearly affected by digestion
Severely digested; prey highly fragmented
Digestion almost complete; unidentifiable remains or indigestible parts only
Digestion complete; stomach empty
Results
In this study, stomach contents of 146 S. canicula (78 male, 240-502 mm TL and 68
female, 215-508 mm TL) were investigated. From the stomach examined 115 had food
(78.8 %), 29 had empty (19.9 %). Only 2 (1.3 %) individuals were determined as
vomited.
According to stomach content’s digestion scale (Table 1), 2 stomachs (1.4 %)
placed into category II, 4 (2.78 %) placed into category III, 39 (27.08 %) into category
IV, 70 (48.61 %) into category V, and 29 (20.14 %) into category VI. No stomach was
found into category I. Since majority of the stomach contents was in category V, it is
difficult to determine the prey items to lower taxon.
As a result of the analysis, fishes and crustaceans were found to be main
important prey groups (MIP; IRI≥352). From these MIP groups, fishes were the most
important prey in lesser spotted dogfish diet (% IRI = 52.00), while crustaceans made
up the second important group (% IRI = 42.07). Polychaetes and Cephalopods
constituted secondary prey groups (SP; 352>IRI>39; % IRI = 3.29 and 2.44,
respectively). Sipunculids (% IRI = 0.20) were considered as occasional prey group
(OP; IRI≤39) (Table 2).
Among the fishes, Engraulis encrasicolus was principal fish prey (% IRI =
5.26), followed by Gobius niger (% IRI = 1.35), Serranus hepatus (% IRI = 0.70),
Scyliorhinus canicula (% IRI = 0.27), Scorpaena sp. (% IRI = 0.20) and Cepola
rubescens (% IRI = 0.19). Unidentified fishes constituted 43.94 % of the diet (Table 2).
Natantia were the principal group (% IRI = 35.95) among the crustaceans,
followed by Squilla mantis (% IRI = 4.67), Brachyurans (% IRI = 0.91), Copepods (%
IRI = 0.05) and Isopods (% IRI = 0.04). Unidentified crustaceans constituted of 0.45%
of the diet (Table 2).
Regarding the polychaetes, except for unidentified polychaetes (% IRI = 3.21),
Hermione hystrix formed 0.08 % of the diet (Table 2).
Loligo vulgaris was principal cephalopod species (% IRI = 1.10), followed by
Octopoda (% IRI = 1.03). Unidentified cephalopods composed 0.31 % of the diet (Table
2).
63
Three-dimensional graphical representation of diet
Use of CORTES (1997) three-dimensional graphical method permitted simple
and rapid characterization of the feeding styles of the species studied (Fig. 2). The diet
of lesser spotted dogfish demonstrated greater heterogeneity and appeared more
generalized. Fish and crustaceans were consumed by nearly half of the individuals, but
fish represented a larger component of prey gravimetrically. Cephalopods, polychaetes
and sipunculids were rare preys.
Discussion
The ratio of empty stomachs was found as 19.9 %. This is somewhat higher than that
found by OLASO et al. (2002) who computed as 14 %. Both the ratio of empty
stomachs and majority of the stomach contents in category V may be affected by long
trawl hauls since the specimens were obtained from commercial trawl boats, and time
interval passed from the field to the laboratory. In our study, we determined that the 2
vomited individuals. The function of vomiting behavior in lesser spotted dogfish is
probably a protective reflex for the expulsion of indigestible matter in their natural diet
and for the avoidance of toxic food (ANDREWS et al., 1998).
The variety of prey items found in this study implies that lesser spotted dogfish
is a broad generalist. Lesser spotted dogfish prey on a wide range of items (polychaetes,
sipunculids, crustaceans, cephalopods, fish), although fishes and crustaceans are their
main food (Table 2). This kind of general, opportunistic and scavenger feeding has been
described by OLASO et al., 1998. They noted dogfish fed on damaged or dead animals
from the fishing operations or on other scavengers attracted to the trawled area.
The dominance of fishes in the diet of lesser spotted dogfish agrees with
previous studies. MACPHERSON (1979) reported that 55.4 % of the diet of lesser
spotted dogfish was constituted by fishes and 35.1 % by crustaceans in the Balearic Sea.
CIHANGIR et al. (1997) recorded, in the order of importance, fishes, decapods
crustaceans and polychaetes for the North Aegean Sea. OLASO et al. (1998) who
studied in Cantabrian Sea, found the diet composition of lesser spotted dogfish as 54.6
% fish, 31.5 % crustaceans, 6.7 % molluscs, 4.2% polychaetes and 0.9 % sipunculids.
KABASAKAL (2001) noted that the diet of lesser spotted dogfish was composed of
71% teleosts, 32 % crustaceans, 21 % cephalopods and 15% polychaetes in the North
Aegean Sea. STERGIOU and KARPOUZI (2002) documented the components of the
diet as 41 % fishes (mainly Micromesistius poutassou and Gadiculus argenteus
argenteus), 26 % decapods, 7 % molluscs and 26 % other groups in the Mediterranean
Sea.
64
Table 2. Percent number (% N), percent weight (% W), frequency of occurrence (% O),
Index of Relative Importance (IRI) and percent Index of Relative Importance
(% IRI) calculated for each prey item found in the stomachs of lesser spotted
dogfish S. canicula
Items
Polychaeta (Total)
Errantia
%N
10.63
Hermione hystrix
Polychaeta(Unidentified)
Sipunculida (Total)
Sipuneulusnudus
Crustacea (Total)
Copepoda
Isopoda
Natantia
Brachyura
Gonopelax rhomboides
Stomotopoda
Squilla mantis
Crustacea (Unidentified)
Cephalopoda (Total)
Decapoda
Loligo vulgaris
Octopoda
Cephalopoda (Unidentified)
Fishes (Total)
Elasmobranchii
Scyliorhinus canicula
Teleostei
Engraulis encrasicolus
Serranus hepatus
Cepola rubescens
Gobius niger
Gobiidae
Scorpaena sp.
Teleostei (Unidentified)
Total
0.88 0.97 0.87 1.61
0.08
9.75 2.10 5.22 61.86 3.21
1.77 0.47 1.74 3.90
0.20
1.77 0.47 1.74 3.90
0.20
39.81 29.90 30.44 810.62 42.07
0.88 0.17 0.87 0.91
0.05
0.88 0.02 0.87 0.78
0.04
23.89 18.05 16.52 692.85 35.95
3.54 1.14 3.48 16.29 0.85
0.88 0.50 0.87 1.20
0.06
65
6.20
3.54
8.85
%W
3.07
8.56
1.46
8.37
%O
6.09
6.09
1.74
7.83
IRI
63.47
89.89
8.70
46.94
%IRI
3.29
4.67
0.45
2.44
3.54 4.59
3.54 2.15
1.77 1.63
38.94 58.19
2.61 21.22
3.48 19.80
1.74 5.92
32.18 1001.83
1.10
1.03
0.31
52.00
0.88
0.87
5.19
0.27
101.28
13.52
3.65
26.07
1.64
3.76
846.72
1926.76
5.26
0.70
0.19
1.35
0.09
0.20
43.94
100
5.09
8.86 7.77 6.09
1.77 6.00 1.74
0.88 3.31 0.87
2.66 7.33 2.61
1.77 0.12 0.87
0.88 3.44 0.87
21.24 25.13 18.26
100
100 78.28
Figure 2. The three-dimensional graphical representation of stomach content data for
S. canicula (Pisc.: Fishes; Crust.: Crustaceans; Ceph.: Cephalopods; Poly.:
Polychaetes; Sipun.: Sipunculida).
However, JARDAS (1979) recorded that the diet in the Adriatic Sea, was
constituted by 43.8 % crustaceans, 29.4 % fishes, 21 % polychaetes and 5.8 %
cephalopods, in the order of importance. GIBSON and EZZI (1987) found that diet
consisted of 44.3 % polychaetes, 37.7 % crustaceans and 12.9 % fish in Scotland.
ELLIS and SHACKLEY (1995) suggested that the diet of lesser spotted dogfish is
composed primarily of decapod crustaceans, molluscs and teleosts in the Northeast
Atlantic. ELLIS et al (1996) recorded in the Northeast Atlantic that diet included 51.6%
crustaceans, 15.9 % teleost, 15.3 % annelids and 14.7 % molluscs. CORTES (1999),
found that diet comprised 42.3 % crustaceans, 17.3 % fish and 4.2 % cephalopods. Such
differences may reflect size-specific and region-specific feeding preferences.
Consequently, this study indicates that lesser spotted dogfish has a relatively
generalized diet. However, it is an interesting finding that among fishes eaten by S.
canicula, E. encrasicolus (anchovy), a pelagic species, is the most dominant. However,
KABASAKAL (2001) stated that many elasmobranchs grow to a large size and have
the ability to prey on both pelagic and benthic communities. Furthermore, there is an
intensive purse seine fishery on anchovy in the sampling area, thus, this may support
that lesser spotted dogfish also feeds on wounded or dead animals in the fishing zone as
an opportunist or scavengers. In addition, we found a little lesser spotted dogfish in the
stomach of a male (465 mm TL). Similarly, OLASO et al. (1998) claimed that
cannibalism occurred in lesser spotted dogfish longer than 50 cm TL. (0.1 % of the
stomach volume).
66
Acknowledgments
No data could have been collected without help and cooperation of fishermen who
allowed us to their ships and Harun Güclüsoy from Underwater Research Society,
Mediterranean Monk Seal Research Group (SAD-AFAG). We would like to thank to
Melih Ertan Cınar, Güley Kurt and Gökcen Bilge for their assistance and support.
References
ALBERT, O. T., 1995. Diel changes in food and feeding of small gadoids on a coastal
bank. ICES J. Mar. Sci. 52, 873-885.
ANDREWS, P. L. R., SIMS, D. W., YOUNG, J. Z., 1998. Induction of emesis by the
sodium channel activator veratrine in the lesser spotted dogfish, Scyliorhinus canicula
(Chondrichthyes: Elasmobranchii). J. Mar. Biol. Ass. U.K. 78, 1269-1279.
CAPAPE, C., 1977. Contribution à la biologie des Scyliorhinidae des cŏtes tunisiennes
Scyliorhinus canicula (L., 1758) Répartition géographique et bathymétrique,
sexualité, reproduction, fécondité. Bull. Off. Natn. Péch. 1(1), 83-101.
CIHANGIR, B., ÜNLÜOĞLU, A., TIRAŞIN, E. M., 1997. Kuzey Ege Denizi’nde
Kedibalığı (Chondrichthyes, Scyliorhinus canicula, Linnaeus, 1758)’nın Dağılımı ve
Bazı Biyolojik Özellikleri. In Akdeniz Balıkcılık Kongresi, 9-11 Nisan 1997-İzmir,
pp 585-603.
CORTES, E., 1997. A critical review of methods of studying fish feeding based on
analysis of stomach contents: application to elasmobranch fishes. Can. J. Fish. Aquat.
Sci. 54, 726-738.
CORTES, E., 1999. Standardized diet composition and trophic levels of sharks. ICES J.
of Mar. Sci. 56, 707-715.
ELLIS, J. R., PAWSON, M. G., SHACKLEY, S. E., 1996. The comparative feeding
ecology of six species shark and four species of ray (Elasmobranchii) in the Northeast Atlantic. J. Mar. Biol. Ass. U. K. 76, 89-106.
ELLIS, J. R., SHACKLEY, S. E., 1995. Ontogenetic changes and sexual dimorphism in
the head, mouth and teeth of the lesser spotted dogfish. J. Fish Biol. 47, 155-164.
FROESE, R., PAULY, D., (ed.) 2003. Fishbase World Wide Web electronic
publications. www.fishbase.org, 20 Sept. 2003.
GELSLEICHTER, J., MUSICK, J.A., NICHOLS, S., 1999. Food habits of the smooth
dogfish, Mustelus canis, dusky shark, Carcharhinus obscurus, Atlantic sharpnose
shark, Rhizoprionodon terraenovae, and the sand tiger, Carcharias taurus, from the
northwest Atlantic Ocean. Environmental Biology of Fishes, 54: 205-217.
GIBSON, R. N., EZZI, I. A., 1987. Feeding relationships of a demersal fish assemblage
on the west coast of Scotland. J. Fish. Biol. 31, 55-69.
HYSLOP, E. J., 1980. Stomach content analysis - a review of methods and their
applications. J. Fish Biol. 17, 411-429.
JARDAS, I., 1979. Morphological, Biological and Ecological Characteristic of the
Lesser Spotted Dogfish, Scyliorhinus canicula (L., 1758), population in the Adriatic
Sea. Reports, Vol. IV, No. 2-3, SPLIT, pp 104.
67
KABASAKAL, H., 2001. Preliminary data on the feeding ecology of some selachians
from the north-eastern Aegean Sea. Acta Adriat. 42(2), 15-24.
KABASAKAL, H., 2002. Cephalopods in the stomach contents of four Elasmobranch
species from the northern Aegean Sea. Acta Adriat. 43(1), 17-24.
MACPHERSON, E., 1979. Relations trophiques des poisons tuns la Mediterranee
occidentale. Rapp. Comm. Int. Expl. Sci. Mer. Medit. 25/26, 49-58.
MORATO, T. M., SOLA, E., GROS, M. P., MENEZES, G., PINHO, M. R., 1998.
Trophic relationships and feeding habits of demersal fishes from the Azores:
importance to multispecies assessment. In: International Council for the Exploration
of the Sea. ICES CM 1998/O: 7, pp 34.
OLASO, I., VELASCO, F., PEREZ, N., 1998. Importance of discarded blue whiting
(Micromesistius poutossou) in the diet of lesser spotted dogfish (Scyliorhinus
canicula) in the Cantabrian Sea. ICES J. Mar. Sci. 55, 331-341.
OLASO, I., VELASCO, F., SÁNCHEZ, F., SERRANO, A., RODRÍGUEZ-CABELLO
C., CENDRERO, O., 2002. Trophic relations of lesser spotted dogfish (Scyliorhinus
canicula) and black mouth dogfish (Galeus melastomus) in the benthic and demersal
communities of the Cantabrian Sea. In Northwest Atlantic Fisheries Organization,
NAFO SCR Doc. 02/123, Serial No. N4745, pp 14.
PINKAS, L., OLHHIPHANT, M. S., IVERSON, I. L. K., 1971. Food habits of
albacore, bluefin tuna and bonito in California waters. California Fish and Game,
152, 1-105.
SIMS, D. W., DAVIES, S. J., BONE, Q., 1996. Gastric empty rate and return appetite
in lesser spotted dogfish, Scyliorhinus canicula (Chondrichthyes: Elasmobranchii). J.
Mar. Biol. Ass. U.K. 76, 479-491.
STERGIOU, K. I., KARPOUZI, V. S., 2002. Feeding habits and trophic levels of
Mediterranean fish. Reviews in Fish Biology and Fisheries 11, 217-254.
VELASCO, F., OLASO, I., SANCHEZ, F., 2001. The role of cephalopods as forage for
the demersal fish community in the southern Bay of Biscay. Fisheries Research 52,
65-77.
68
Proc. of the Int. Workshop on Med. Cartilaginous Fish with Emphasis on South.- East. Med., 14-16 Oct. 06, Istanbul-Turkey
PRELIMINARY RESULTS ON DEPTH DISTRIBUTION OF
CARTILAGINOUS FISH IN THE NORTH AEGEAN SEA AND THEIR
FISHING POTENTIAL IN SUMMER 2001
Çetin KESKİN and F. Saadet KARAKULAK
Istanbul University, Fisheries Faculty, Ordu St. No: 200, 34470 Laleli/ İstanbul, Turkey,
E-mail: seahorse@istanbul.edu.tr
Abstract
The aim of this study was to determine the depth distribution of cartilaginous fish in the
North Aegean Sea in August, 2001. Samplings were carried out using bottom trawl at
13 stations ranging from the depth of 40 m to 500 m (total trawling time was 8.6 h). A
total of 29223 fish specimens (total weight: 621.2 kg) were recorded. The total number
of cartilaginous specimens (3 % of total specimens) were 863; 114.3 kg in weight (18 %
of total weight). The most abundant cartilaginous fish species was Scyliorhinus canicula
(total mean biomass: 2850.6 kg/nm2 (kilogram/nautical mile square)), and it was caught
in all depths. Torpedo marmorata, Raja radula and Dipturus oxyrinchus were sampled
rarely.
Key Words: North Aegean Sea, elasmobranchs, depth distribution.
Introduction
Elasmobranch fish are common but unspecified by-catch in many fisheries all over the
world, particularly those using bottom trawls, long-lines, or gill nets (STEVENS et al.,
2000). Serious declines have been documented for a number of shark and ray
populations in recent years. Over human exploitation and habitat degredation are main
threats to elasmobranch populations (CORTES, 2000; ELLIS et al., 2002; HEESSEN,
2002; PRINCE, 2002). It is reported that there have been havested more than 700000 t
cartilaginous fish annually worldwide (BONFIL, 1994; FRISK et al., 2001).
BILECENOĞLU et al. (2002) reported that 64 elasmobranch species were found in the
Turkey’s seas. Among them 38 are important economical species (FİLİZ and
TOGULGA, 2002). Total havesting amount in Turkey is 965 t in 2003 (DIE, 2003).
A number of investigations have been carried out on the distribution, taxonomy
and biology of elasmobranch fish in Turkey’s seas (BENLİ et al., 1993; UYSAL et al.,
1996; CIHANGIR et al. 1997; KABASAKAL and ÜNSAL, 1999; KABASAKAL,
1998a, b; 1999; 2001, 2002, 2003, 2004; ERYILMAZ, 2000; AVSAR, 2001; FİLİZ and
MATER, 2002; ISMEN, 2003). BENLİ et al.(1999) investigated on the some demersal
fisheries researches in the Aegean Sea. Fisheries management of economical
elasmobranch species in Turkish sea was reported by FİLİZ and TOGULGA (2002).
69
The aim of this study was to determine the depth distribution and fisheries
potential of elasmobranchs in the North Aegean Sea.
Materials and Methods
This study was conducted in the North Aegean Sea from 03.08.2001 to 11.08.2001.
Samples were collected by bottom trawl at 13 stations (depth range: 40 to 500 m)
(Figure 1). The head-rope length of the trawl net was 21,6 m and the cod-end mesh size
was 20 mm (bar lenght). The trawling speed was 2.2-2.6 nm/h (nautical mile/hour). The
duration of each haul, and the trawling areas are showed in Table 1.
Fish species were identified according to WHITEHEAD et al. (1984), and the
number of individuals and the total weight of each species were determined, and
biomass was estimated based on the swept area method (SPARRE and VENEMA,
1992). The mean biomass per unit area (b) was calculated by using the formula:
b = (cw/a)/X1 (kg/nm2)
where cw is the catch in weight of a haul, X1 is the fraction of the biomass in the
effective path swept by the trawl (X1=1 was used), and “a” is swept area, which can be
estimated from; a= D*h*X2, D= v*t (h is the length of the head-rope, “t” is the time spent
trawling, X2 is that fraction of the head-rope length (X2=0.5 was used))
Samples were taken over a wide depth range and divided into four depth strata
for analysis: (A) between 40 and 50 m; (B) between 80 and 105 m; (C) between 200 and
300 m; and (D) between 300 and 500 m. Mean biomass values were calculated for all
four depth strata.
The frequency degree of species for each strata was calculated as follows:
F=(Na/N)*100
Where Na is sampling number of species a. N is total sampling of each strata.
70
Figure 1. Sampling stations in the North Aegean Sea.
Table 1. Towed area and duration of hauls per depth strata in the study area
Stations
1
2
3
4
5
6
7
8
9
10
11
12
13
Coordinates
40°14'35″N - 25°41'39″E
39°39'26″N - 26°06'26″E
39°28'02″N - 25°52'00″E
39°27'30"N - 26°19'00″E
39°24'42″N - 26°30'16″E
39°31'07″N – 25°4' 42″E
39°59'04″N - 25°48'59″E
40°05'35″N - 25°55'52″E
40°17'16″N - 25°55'11″E
40°33'51″N - 26°22'25″E
40°19'20″N - 25°57'32″E
40°16'37″N - 25°54'03″E
40°12'44″N - 25°32'06″E
40°13'57″N – 25°40'18″E
39°38'29″N – 26°05'34″E
39°26'11″N – 25°50'52″E
39°27'24"N – 26°21'30″E
39°25'29″N – 26°31'12″E
39°29'06″N – 25°54'35″E
39°58'43″N – 25°47'37″E
40°04'59″N – 25°54'40″E
40°16'14″N – 25°52'25″E
40°34' 09″N- 26°20'41″E
40°17'51″N – 25°56'37″E
40°15'40″N – 25°51'19″E
40°12'52″N – 25°29'33″E
71
Depth
(m)
314-447
40-45
300-310
105
99
266-300
83
43-49
200-280
80
490-350
226
486
Total
Time (h)
0.5
0.5
1
0.5
0.5
1
0.5
0.5
1
0.5
0.7
0.5
1
Surface
(nm2)
0.006
0.006
0.012
0.006
0.006
0.012
0.007
0.007
0.015
0.007
0.007
0.007
0.012
Results
A total of 11 elasmobranch species belonging to 5 families were caught in the North
Aegean Sea. While Scyliorhinus canicula, Rostraraja alba, Raja clavata and Raja
asterias were caught at all four depth strata, Galeus melastomus, Raja radula, Dipturus
oxyrinchus and Torpedo marmorata were caught very rarely (Table 2).
Table 2. List of elasmobranchs, frequency degree (f) and distribution in the various
depth strata
Family
Species
Scyliorhinidae
Scyliorhinus canicula
Galeus melastomus
Squalus blainvillei
Etmopterus spinax
Rostraraja alba
Raja miraletus
Raja clavata
Raja asterias
Raja radula
Dipturus oxyrinchus
Torpedo marmorata
Squalidae
Dalatiidae
Rajidae
Torpedinidae
f
50
100
100
100
50
50
40-50
m
+
+
+
+
+
+
f
100
50
100
50
25
80-105
m
+
+
+
+
+
-
f
100
33.3
33.3
33.3
33.3
66.3
33.3
200-300
m
+
+
+
+
+
+
+
-
f
100
75
25
75
25
25
25
25
25
300-500
m
+
+
+
+
+
+
+
+
+
-
Total catch composition: Commercial, discard and elasmobranchs
A total of 29233 fish (621.4 kg) were collected by 13 trawl hauls, during 8,6
hours, ranging from 40 m to 500 m. A total number of fish representing 11
elasmobranch species were 863 individuals (3 % of total fish number); 114.3 kg (18 %
of total fish weight). The total weight of commercial species was 285.7 kg (46 % of the
total fish weight), discard weight was 221.3 kg (36 %) (Table 3).
Depth variations in mean biomass of elasmobranchs, commercial and discard fish
Mean biomass of elasmobranchs was the lowest value (8.3 % of the mean total
biomass) in the 300-500 m, although the highest value was observed in the 40-50 m
(48.7 %) (Fig. 2). Mean biomass of commercial fishes was higher in the 80-105 m (56.3
%), 200-300 m (53.8 %) and 300-500 m (50.1 %), respectively, than in the 40-50 m
(25.3 %). Mean biomass value of discard fish was lower in the 200-300 m (22 %), 4050 m (26 %), and 80-105 m (27.9 %), respectively, than in the 300-500 m (41.6 %) (Fig.
2).
72
Table 3. General summary of the hauls analyzed (A: 40-50 m; B: 80-105m; C: 200-300
m; D: 300-500 m)
Stations
Min- max
depth (m)
Duration
(h)
2/A
8/A
10/B
7/B
5/B
4/B
12/C
6/C
9/C
3/D
1/D
11/D
13/D
Totals
40 - 45
43 - 49
80
83
99
105
226
266 - 300
200 - 280
300 - 310
314 - 447
490 - 350
486
0.5
0.5
0.5
0.5
0.5
0.5
0.5
1
1
1
0.5
0.6
1
Trawled
area
(nm2)
0.006
0.007
0.007
0.007
0.006
0.006
0.007
0.012
0.015
0.012
0.006
0.007
0.012
Commercial
(kg)
Discard
(kg)
Elasmobranchs
(kg)
8.2
11.5
24.2
17.5
8.2
21.5
31.4
17.1
30.6
22.8
59.5
10.4
23.0
285.7
15.4
4.9
11.1
5.9
3.7
14.7
2.3
33.9
6.5
37.4
16.8
24.8
44.0
221.3
22.6
15.2
5.1
8.3
4.5
2.5
7.5
20.0
6.1
5.4
3.4
9.0
4.8
114.3
Total
catch
(kg)
46.2
31.6
40.3
31.7
16.4
38.6
41.2
71.0
43.2
65.6
79.6
44.2
71.8
621.4
100%
80%
60%
40%
20%
0%
40-50m
80-105m
200-300m
300-500m
Elasmobranchs
2898,0
769,7
1292,1
592,0
Discard
1559,1
1376,7
1171,2
2961,1
Commercial
1493,8
2776,8
2871,0
3566,8
Figure 2. Percentages of mean biomass, and mean biomasses (kg/nm2) of commercial,
discard and elasmobranch fish in the four depth strata.
S. canicula was the most abundant elasmobranch species (total mean biomass:
2855.1 kg/nm2). In terms of depth strata, the most abundant species was S. canicula in
73
the 40-50 m (1634.3 kg/nm2) and 200-300 m (904.2 kg/nm2); R. clavata (444.8 kg/nm2)
was in the 80-105 m; and G. melastomus (340 kg/nm2) was in the 300-500 m (Table 4).
Table 4. Mean biomasses (kg/nm2) of commercial, discard and elasmobranch fish
species in the four depth strata
Commercial
Discard
S. canicula
G.melastomus
S. blainville
E. spinax
R. alba
R. miraletus
R. clavata
R. asterias
R. radula
D. oxyrinchus
T. marmorata
Total (kg/nm2)
40-50m
Mean
SD
1493.8
312.1
1559.1 1180.2
1634.3 2247.9
865
103.6
257.3
5.2
1117.5
91.8
184.4
7.4
32.6
5950.9
46.1
5187.3
80-105m
Mean
SD
2689.6
978.3
1348.7
796.6
252.8
215.1
15.4
12.8
30.9
22.1
444.8
42.9
1
392.3
56.6
2
4808
2493.9
200-300m
Mean
SD
2871
1490
1171.2 1042.2
350.2
904.2
1.9
251.3
26
0.3
99.1
9.4
5334.3
2.6
351.4
36.7
0.4
70.4
13.2
3357.2
300-500m
Mean
SD
3569.6 4117.3
2967.6
337.1
63.8
50.6
402.8
340
1.6
3.1
68.8
68.7
44.8
89.6
11.7
23.4
58.5
116.9
0.9
1.8
1.9
3.9
7129.2
5215.3
Total (kg/nm2)
Mean
SD
10624
6897.7
7046.6
3356.1
2863.8
2855.1
340
402.8
3.5
5.7
335.5
451
948.6
1265.9
115.6
115.6
859.7
764
58.4
79
1
2
1.9
3.9
32.6
46.1
23222.4 16253.7
Discussion and Conclusion
The number of elasmobranch species living in Turkish seas according to different
authors is showed in Table 5. A total of 11 elasmobranch species were caught in this
study. All these species were benthic forms; 4 species were sharks, and 7 species were
rays. The present study was carried out only in one season (summer) and only by
bottom trawl. For this reason, the number of species captured in this study was much
lower than that of the total identified elasmobranch species (57 species) in the Aegean
Sea, given in Checklist of the Marine Fishes of Turkey (BİLECENOĞLU et al., 2002).
Table 5. The number of elasmobranch fish species in Turkish seas according to different
authors
KOCATAŞ et al. (1987)
KOCATAŞ et al. (1993)
MERİÇ and MATER (1996)
ERYILMAZ (2000)
ERYILMAZ and MERİÇ
(2005)
BİLECENOĞLU et al. (2002)
Black
Sea
Sea of
Marmara
7
12
22
13
Aegean
Sea
Mediterranean
Turkey
43
52
50
54
57
61
64
31
8
33
It was determined that S. canicula was the most abundant species during the
research period. According to WHITEHEAD et al. (1984), this species has a wide
74
distribution range extending a wide bathymetric range and spatial area in the Northeast
Atlantic and the Mediterranean Sea. Also, CARRASSON et al. (1992) and MORANTA
et al. (1998) indicated that this species was found abundantly in 150 m depth and that
the distribution ranges extended to 500 m. In this study, S. canicula was mostly caught
at 40-50 m depth (1635.3 kg/nm2). In the trawl surveys carried out by JICA (1993) in
the North Aegean Sea and by CARNOBELL et al. (2003) in the Mediterranean Sea
(Baleric Islands), it was determined that S. canicula was found as the most abundant
species only in the Summer period. These results confirmed by our findings.
CARRASSON et al. (1992) and MORANTO et al. (1998) stated that G.
melastomus is the most abundant demersal shark on the upper and middle slope down to
about 1400 m in depth in the western Mediterranean. It is clear from the study carried
out by CARNOBELL et al. (2003) that E. spinax and G. melastomus were caught in the
western Mediterranean Sea at waters deeper than 150 m and that the biomasses of the
two species are more than that of S. canicula. In this study, E. spinax and G.
melastomus were caught at deeper waters than 200 m, and these two species were more
abundant than the other species.
It was estimated that the value of total biomass in the Summer 1994 in the
North Aegean Sea was 16,9*103 t (BENLİ et al., 1999). The ratio of teleost fish in the
total biomass was 50 %, and the proportion of sharks and rays was 45 %, the rest part of
total biomass (5 %) was formed by ahtapods, squids, shrimps and lobsters. It was
reported in the same study that the ratio of S. canicula in total elasmobranchs was 80 %.
In this study, the mean portion of sharks and rays in the total biomass is 31 %, and the
ratio of S. canicula in the total elasmobranchs is 51 %. This difference between results
of these two studies can be a sing to the declining of stocks.
Unfortunately, there are not any statistical records for elasmobranch species
caught in Turkey. According to DIE (2003), the total production of elasmobranchs was
965 t. It was determined that this amount was composed of three groups, sharks (400 t),
angel sharks (25 t), and rays (540 t). Of all elasmobranch species, Squalus acanthias
(piked dogfish), Scyliorhinus spp (spotted dogfish), and Raja spp (rays) are the most
commercially valuable species in Turkey. According to the export registers, they are
exported as fresh, frozen, and fillet. Turkey made 305039 $ by exporting the products of
82,8 t (DIE, 2003).
The elasmobranchs, considered as commercial species, are generally caught by
bottom trawl as by-catch in the Mediterranean Sea (BONFIL, 1994; BERTRAND et al.,
2000). Because of the higher rates of population increase and shorter generation times,
small coastal sharks, such as scyliorhinids may be able to sustain commercial fisheries
with careful conservation and management in contrast to deep-water shark species,
which are generally considered to be more vulnerable to exploitation (CAMHI et al.,
1998; WALKER, 1998).
This preliminary study shows that there may be an important fishing potential
of some elasmobranchs, such as S. canicula and Raja spp in the North Aegean Sea. For
this reason, it is vital to determine the commercial elasmobranchs stocks, and to study
their biological aspects. It is also important to develop an appropriate fisheries
75
management plan for these species from the point of view of the conservation of the
ecosystem and sustainable fisheries.
Acknowledgements
We would like to thank Prof. Dr. Bayram ÖZTÜRK and M.Sc. Elif ÖZGÜR for their
valuable contribution in composing the paper.
References
AVSAR, D., 2001. Age, Growth, Reproduction and Feeding of the Spurdog (Squalus
acanthias Linnaeus, 1758) in the South-eastern Black Sea. Estuarine, Coastal and
Shelf Science 52, 269-278.
BENLİ, H. A., CİHANGİR, BİZSEL, K. C., 1993. A nex record for the Sea of Marmara
(Family: Squalidae) Centrophorus granulosus (Blonh & Schneider, 1801). Doğa-Tr.
J. of Zoology 17, 133-135.
BENLİ, H. A., CİHANGİR, B., BİZSEL, K. C., 1999. Ege Denizi’nin Bazı Demersal
Balıkçılık Kaynakları Üzerine Araştırmalar. İ.Ü. Su Ürünleri Dergisi, özel sayı, 301370.
BERTRAND, J., GIL DE SOLA, L., PAPACONSTANTINOU, C, RELINI, G.
SOUPLET, A., 2000. Contribution on the Distribution of Elasmobranchs in the
Mediterranean from the Medits Surveys. Biol. Mar. Medit. 7 (1), 1-15.
BİLECENOĞLU, M., TASKAVAK, E., MATER S., KAYA, M. 2002. Checklist of the
Marine Fishes of Turkey (Zootaxa 113), ISBN 0-9582395-4-1, Published by
Magnolia Pres, New Zealand, pp 194.
BONFIL, R., 1994. Overview of World Elasmobranch Fisheries. FAO Fish. Tec. Pap.
Rome 341, pp 119.
CAMHI, M., FOWLER, S., MUSIRK, J., BRÄUTIGAM, A., FORDHAM, S., 1998.
Sharks and their Relatives-Ecology and Conservation. IUCN/SSC Shark Specialist
Group. IUCN, Cambrige, UK, IV+39 pp.
CARBONELL, A., ALEMANY, F., MERELLA, P., QUETGLAS, A., ROMÁN, E.,
2003. The by-catch of Sharks in the Western Mediterranean (Balearic Islands) Trawl
Fishery. Fisheries Research 61, 7-18.
CARRASON, M., STEFANESCU, C., CARTES, J. E., 1992. Diets and Batymetric
Distributions of Two Batyal Sharks of the Catalan Deep Sea (Western
Mediterranean). Mar. Ecol. Prog. Ser. 82, 21-30.
CIHANGIR, B., UNLUOGLU, A., TIRASIN, E. M., 1997. Distribution and Some
Biological Aspects of the Lesser Spotted Dogfish (Chondrichthyes, Scyliorhinus
canicula, Linnaeus, 1758) from the northern Aegean Sea. Mediterranean Fisheries
Congress. 9-11 April 1997, pp 585-603.
CORTES, E., 2000. Life History Pattern and Correlations in Sharks. Reviews in
Fisheries Science 8 (4), 299-344.
DIE, 2003. Fishery Statistics 2003. State Institute of Statistics Prime Ministry Republic
of Turkey, Ankara, Publication Number 2937, pp 49.
76
ELLIS, J. R., RACKHAM, B. B., ROGERS, S. I., 2002. The distribution of
Chondriyans Fishes around the British Isles and their Conservation Status. In:
Northwest Atlantic Fisheries Organisation. NAFO SCR Doc. 02/101, No. N4722, pp
7.
ERYILMAZ, L., S. 2000. A study on the Cartilaginuous Fishes Caught with the Bottom
Trawling and their Morphologies in the South of the Sea of Marmara. İstanbul
Üniversitesi Biyoloji Dergisi 62, 25-44.
ERYILMAZ, L., MERİÇ, N., 2005. Review of Fish Fauna of the Sea of Marmara,
Journal of the Blacksea / Mediterranean Environment 11 (2), 153-178.
FİLİZ, H., MATER S., 2002. A Preliminary Study on Length-Weight Relationships for
seven Elasmobranc Species from North Aegean Sea, Turkey. E. U. Journal of
Fisheries and Aquatic Science 19 (3-4), 401-409.
FİLİZ, H., TOGULGA, M., 2002. Türkiye Denizlerindeki Ekonomik Elasmobranş
Türleri, Balıkçılığı ve Yönetimi. Türkiye’nin Kıyı ve Deniz Alanları IV. Ulusal
Konferansı, In: ÖZHAN, E., ALPASLAN, N., (Eds)Türkiye Kıyıları 02 Bildiri
Kitabı, 5-8 Kasın 2002, pp 717-726.
FRISK, G. M., MILLER, T. J., FOGARTY, M. J., 2001. Estimation and Analysis of
Biological Parameters in Elasmobranch Fishes: a comparative life history study.
Canadian Journal of Fisheries 58 (5), 969-982.
HEESSEN, H. L., 2002. Development of the Elasmobranch Assesment (DELASS). In:
Northwest Atlantic Fisheries Organisation. NAFO SCR Doc. 02/112, No. N4733, pp
4.
ISMEN, A., 2003. Age, Growth, Reproduction and Food of Common Stingray
(Dasyatis pastinaca L., 1758) in İskenderun Bay, the eastern Mediterranean.
Fisheries Research 60, 169-176.
JICA, 1993. Report of Demersal Fisheries Resource Survey in the Republic of Turkey.
JICA, AFF, JR. 63, pp 579.
KABASAKAL, H., 1998a. A Note on the Occurence of the Thresher Shark, Alopias
vulpinus from South-west Black Sea. J. Mar. Biol. Ass. U.K. 78, 685-686.
KABASAKAL, H., 1998b. The First Record of the Speckled Ray, Raja (Raja)
polystigma Gegan, 1923 in the Seas of Turkey. Acta Adriat. 39(1), 61-66.
KABASAKAL, H., 1999. A Note on the Diet of Five Deep-sea Fishes from the NorthAegean Sea. Institut Za oceanografiju I Ribarstvo-split, Hrvatska, Biljeske-Notes 82,
8 pages.
KABASAKAL, H., 2001. Preliminary Data on the Feeding Ecology of Some Selachians
from the North-eastern Aegean Sea. Acta Adriat. 42 (2), 15-24.
KABASAKAL, H. 2002. Cephalopods in the Stomach Contents of Four Elasmobranch
Species from the Aegean Sea. Acta Adriat. 43 (1), 17-24.
KABASAKAL, H., 2003. Historical Recards of the Great White Shark, Carcharodon
carcharias (Linnaeus, 1758) (Lamniformes, Lamnidae), from the Sea of Marmara.
Annales, Ser. Hist. Nat. 13 (2), 173-180.
KABASAKAL, H., 2004. Preliminary Obsevations on the Reproductive Biology and
Diet of the Bluntnose Sixgill Shark, Hexanchus griseus (Bonnaterre, 1788)
(Chondrichthyes: Hexanchidae) in Turkish Sea. Acta Adriat. 42 (2), 187-196.
77
KABASAKAL, H., ÜNSAL, N., 1999. Obsevations on Etmopterus spinax (Pisces:
Squalidae), from the North-eastern Aegean Sea. Institut za Oceanografiju i RibarstvoSplit Hrvatska. Biljeske-Notes, No: 81.
KOCATAŞ, A., ERGEN, Z., MATER, S., ÖZEL, I., KATAĞAN, T., KORAY, T.,
ÖNEN, M., KAYA, M., 1987. Biological diversity in Turkey. Environmental
Problems Foundation of Turkey, pp 144-161
KOCATAŞ, A., T. KORAY, M. KAYA, KARA, Ö. F., 1993. Review of the Fishery
Resources and their Environment in the Sea of Marmara. Studies and Reviews
General Fisheries Council for the Mediterranean 64, pp 87-143.
MERİÇ, N., MATER, S. 1996. Deniz Balıkları, Pisces. In: A. KENCE, and C.C.
BILGIN (Eds.): Türkiye Omurgalılar Listesi, TÜBİTAK, Ankara, pp 131-183.
MORANTA, J. STEFANESCU, C., MASSUTI, E., MORALES-NIN, B., LLORIS, D.,
1998. Fish Community Structure and Depth-related Trends on the Continental Slope
of the Balearic Islands (Algerian basin, Western Mediterranean). Mar. Ecol. Prog.
Ser. 171, 247-259.
PRINCE, J. D., 2002. Gauntlet Fisheries for Elasmobrachs- the Secret Sustainable
Shark Fisheries. Northwest Atlantic Fisheries Organisation. NAFO SCR Doc. 02/139,
No. N4761, pp 16.
SPARRE, P., VENEMA, S. C., 1992. Introduction to Tropical Fish Assessment, Part I –
Manual, FAO Fisheries Tecnical Paper 306/1 Rev. 1, Roma, pp 376.
STEVENS, J. D., BONFIL, R., DULVY, N. K., WALKER, P. A., 2000. The effects of
fishing on sharks, rays, and chimaeras (chondrichthyans), and the implications for
marine ecosystems. ICES Journal of Marine Science 57, 476-494.
UYSAL, A., YÜKSEK, A., OKUS, E., 1996. Marmara Denizi’nde Ender Rastlanan Üç
Elasmobranchii Türü ve Dağılımları (Raja naevus, Müller and Hendle 1841; Raja
oxyrinchus, Linnaeus 1758; Galeus melastomus Rafinesque 1809). VIII. Biyoloji
Kongresi, 17-20 eylül 1996, Bildiri ve Poster Özetleri Hidrobiyoloji Seksiyonu. Cilt
V, 118-127.
WALKER, T. L., 1998. Can Shark Resources be Harvested Sustainably? A Question
Revisited with a Review of Shark Fisheries. Mar. Freshw. Res. 49, 553-572.
WHITEHEAD, P. J. P., BAUCHOT, M. L., HUREAU, J. C., NIELSEN, J.,
TORTONESE, E., 1984. Fishes of the North-eastern Atlantic and Mediterranean,
Vol. I. UNESCO, U. K., pp 510.
78
Proc. of the Int. Workshop on Med. Cartilaginous Fish with Emphasis on South.- East. Med., 14-16 Oct. 06, Istanbul-Turkey
THE PRODUCTION AND ECONOMIC IMPORTANCE OF SHARKS IN
TURKEY
Kadir DOĞAN
Istanbul University Faculty of Fisheries, Aquaculture Department, Ordu St. No: 200, 34470
Laleli/ Istanbul, Turkey. E-mail: kadogan@istanbul.edu.tr
Abstract
The production and economic values of sharks in Turkey have been analysed for the last
34 years. Along these years, the maximum catch level was recorded in 1979 as 11.125 t.
A significant decrease observed after 1989 and it reached to the minimum level of 400 t
in 2003.
In spite of its rare consumption in internal market, sharks fishery contributes to
Turkey’s economy as an export product. They were exported to the other countries as
fresh/chilled, frozen, topeshark fillets, dried, salted or in brine products. Total sale was
US$ 738.080 in 1993 with the exports of 309.461 kg and US$ 211.879 in 2003 with the
exports of 52.394 kg.
Key words: Cartilaginous trade, economic importance of shark.
Introduction
As it was pointed out by SPAGNOLO (1999), shark landings show a decreasing trend
and therefore increasing attention is being paid to the state of stocks. However, sharks
have been little studied in Turkey, except for a few works SLASTENENKO (1956),
KUTAYLIGIL and BILECIK (1998). Around 470 true shark species have been
recorded around the world and only 63 of those species live in Turkey KENCE and
BILGIN (1996). The phenomenon is hard to monitor since there is very little experience
of shark fisheries in the world SPAGNOLO (1999).
The aim of this paper is to provide data on production of sharks and on their
economic value in Turkey.
Materials and Methods
The main source of the present report will be compiled with the national and
international studies. During the 1970 to 2003, the total Sharks production which was
obtained by hunting, its distribution according to the region, and amount of the exports
have been evaluated using the Turkish Statistical Institute, Fishery Statistics. Only true
sharks data was used in this study, other species, like rays, were not included.
To understand economical value of the shark production to the Turkish
economy, several studies e.g. ACARA (1992, 1996), ACARA et al. (1993, 1998),
79
SENEL et al. (1999, 2000, 2001, 2002), GOZGOZOGLU et al. (2004, 2005) have been
used.
Results and Discussion
850
800
750
1000 t
2003
2002
2001
2000
1999
1998
1997
1996
1995
700
Production value (US$
million)
800
780
760
740
720
700
680
900
1994
Total production (1000 t)
Production of Sharks
The production of sharks in the world did not vary considerably for the period
of 1994 and 2003 (Fig. 1). Sharks do not take an important place in the world total fish
production. It accounted for only 0.7 % of the total production.
US$ mill
Figure 1. World shark production and production value in 1994-2003 (Source: URL1).
On the other hand, shark production showed big fluctuations among the years
in Turkey. The total production of sharks was 1198 t in 1970 and reached to the last 34
years’ maximum (11.125 t) in 1979. After that, the production showed a dramatic
decrease and only 400 t was caught in 2003. The production of sharks in Turkish waters
is shown in Table 1 and Figure 2.
Table 1. The production of sharks in Turkish waters between 1970 and 2003 (t)
Year
East
Black
Sea
West
Black Sea
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
400
2.373
1.876
418
1.305
1.178
1.098
672
10.738
122
212
206
25
41
115
456
150
Marmara
Sea
Aegean
Sea
Mediterranean
Sea
Total
Shark
Production
415
242
236
160
389
62
113
177
23
10
106
2
1
11
22
181
51
59
31
20
156
257
293
105
45
16
52
44
609
208
1.199
3.085
2.559
719
1.803
159
1.395
1.494
1.791
11.125
80
Table 2 (Cont.)
Year
East
Black
Sea
West
Black Sea
Marmara
Sea
Aegean
Sea
1980
4.210
492
133
33
1981
4.202
1.400
218
101
1982
5.113
1.637
255
118
1983
4.375
2.786
269
35
1984
854
3.734
348
45
1985
1.537
1.061
203
128
1986
2.195
386
470
71
1987
2.670
469
572
86
1988
2.790
471
670
136
1989
2.922
1.636
229
76
1990
797
262
345
103
1991
740
1.277
18
106
1992
857
1.363
25
101
1993
533
522
112
1994
463
1.969
79
129
1995
49
1.513
45
83
1996
70
1.678
205
65
1997
278
1.232
64
34
1998
302
553
225
242
1999
17
1.461
29
40
2000
60
2.330
269
103
2001
129
447
137
188
2002
49
267
146
121
2003
29
155
85
71
Source : 1970-2003 Fishery Statistics, Turkish Statistical Institute.
Mediterranean
Sea
Total
Shark
Production
122
352
211
357
254
62
81
98
148
277
208
151
58
269
240
93
140
112
128
78
118
99
103
60
4.990
6.273
7.334
7.822
5.235
2.911
3.203
3.895
4.215
5.140
1.715
2.292
2.404
1.436
2.880
1.783
2.158
1.720
1.450
1.625
2.880
1.000
686
400
As it can be seen in Fig. 2, the shark production varies between the seas and fluctuates
distinctively among the years. Most of the sharks have been caught in the Black Sea
KABASAKAL (2003) and it accounted for 84 % of the total production of last 34 years
fıshery statıstıcs (DIE, 1970-2003). 54 % of catch is from the Eastern Black Sea, 30 %
from Western Black Sea, 7 % from the Marmara Sea, 6 % from the Mediterranean Sea
and 3 % from the Aegean Sea.
Sharks are caught by long lines, gill-nets and deep trawls. Although, their
production is based on generally by-catches of deep trawling, anchovy and turbot
fisheries in Turkey KABASAKAL (1998).
Economical Importance
Sharks are consumed in many countries. Especially, fins are one of the most
expensive products of fish in the world. The market of the sharks fins present in
especially Asia, Hong Kong, Singapur, Taivan, China (SENGOR, 2005). Sharks fins are
not consumed in Turkey, therefore most of them are exported to other countries with or
without processing (KABASAKAL and KABASAKAL, 2004). Sharks are sold to the
other countries as fresh/chilled Scyliorhinus spp; Dogfish frozen and fillets, Topeshark
81
fillets, dried, salted or brine. In Table 4 shows the amount and values of exported sharks
products from Turkey.
According to the fishery statistics, the average price of sharks was 1.3 $/kg in
2003 while it was 0.8 $/kg in 2000 and 1.0 $/kg. in 1994 fıshery statıstıcs (DIE, 19702003).
700
Production (t)
600
500
400
300
200
100
2002
2000
1998
1996
1994
1992
1990
1988
1986
1984
1982
1980
1978
1976
1974
1972
1970
0
Years
Aegean Sea
Mediterranean Sea
2002
2000
1998
1996
1994
1992
1990
1988
1986
1984
1982
1980
1978
1976
1974
1972
11000
10000
9000
8000
7000
6000
5000
4000
3000
2000
1000
0
1970
Production (t)
Marmara Sea
Years
East Black Sea
West Black Sea
Figure 2. The annual production of sharks in Marmara, Aegean and Mediterranean Sea
(Upper panel) and East and West Black Sea (Lower panel).
82
In 2003 the average sales price of sharks per kg was 1.3 $ in the Eastern Black
Sea, 1.2 $ in Western Black Sea, 1 $ Marmara Sea, 1.4 $ Aegean Sea, and
Mediterranean Sea and it provided 535.406 $ supplementary budget to the country
economy with the average sales price of 1.3 $ per kg. The increasing economical value
of sharks in Turkey is given in Table 2 and Fig. 3. As it is seen from the table, the value
was 1.055.373 $ in 1985 while it was 1.733.779 $ in 1990 and 2.308.787 $ in 2000.
This ratio accounts for the 1 % of the total fish production in Turkey ACARA (1992),
ACARA et al. (1993), SENEL et al. (2000), GOZGOZOGLU et al. (2004),
GOZGOZOGLU et al. (2005).
The exportation of sharks in the world showed an increasing trend in recent
years. In 1995, US$ 42,546 billion of revenue was achieved with the exported products
of 17,956 t (URL1). This value was US$ 41,130 with 16,130 t in 1999. On the other
hand, the export quantity was 309.461 kg in Turkey in 1993 and decreased to the 52.394
kg with the revenue of US$ 211.879 in 2003 (Table 3 and Fig. 4).
Table 2. The positive effect of sharks to the country economy according to the regions
in 1985-2003 ($) (ACARA, 1992, 1996; ACARA et al., 1993, 1998; SENEL
et al., 1999, 2000, 2001, 2002; GOZGOZOGLU et al., 2004, 2005)
Year
1985
1986
1987
1988
1989
1990
1991
1992
1995
1996
1997
1998
1999
2000
2001
2002
2003
Eeatern
Black
Sea
250.820
1.006.872
2.950.801
1.963.682
2.249.623
916.935
709.849
68.385
107.283
56.460
169.505
215.613
14.995
48.098
71.057
28.348
38.446
Western
Black
Sea
613.544
403.346
548.089
331.503
771.407
301.427
1.224.969
1.978.947
3.126.430
1.820.084
821.283
492.201
1.165.114
1.861.819
307.816
83.456
194.572
Marmara
Sea
Aegean
Sea
Mediterranean
Sea
117.692
491.485
668.459
471.565
107.978
396.917
17.267
36.298
98.525
220.735
37.496
186.237
22.584
210.943
86.091
126.780
113.949
73.317
74.694
100.503
95.721
53.753
118.500
101.681
146.642
181.725
82.187
38.625
330.111
38.938
93.495
131.983
107.641
104.665
101.810
136.045
125.729
58.314
73.449
94.432
55.895
91.302
83.774
83
Total
Shark
production
1.055.373
1.976.397
4.267.852
2.862.471
3.182.761
1.733.779
2.053.766
2.230.272
3.615.773
2.315.511
1.192.638
1.282.476
1.315.080
2.308.787
652.842
437.527
535.406
Total marine
fish
production
296.380.474
442.455.931
509.142.223
539.452.421
392.931.440
767.293.297
813.436.773
956.500.036
1.383.943.096
918.363.824
704.912.395
796.808.015
596.764.734
510.167.483
344.701.308
348.147.993
462.059.560
3.500.000
3.000.000
Value (US$)
2.500.000
2.000.000
1.500.000
1.000.000
500.000
2003
2001
1999
1997
1995
1991
1989
1987
1985
0
Years
East Black Sea
West Blsck Sea
800.000
700.000
Value (US$)
600.000
500.000
400.000
300.000
200.000
100.000
2003
2002
2001
2000
1999
1998
1997
1996
1995
1992
1991
1990
1989
1988
1987
1986
1985
0
Years
Marmara Sea
Aegean Sea
Mediterranean Sea
Figure 3. Total income of shark production in East and West Black Sea (upper panel)
and Marmara, Aegean and Mediterranean Seas (lower panel).
84
Table 3. Exported sharks production of Turkey, 1993-2003
Value (US$)
738.080
365.826
498.929
243.327
434.449
429.010
174.074
363.207
447.062
383.881
211.879
800.000
700.000
600.000
500.000
400.000
300.000
200.000
100.000
0
350.000
Quantity (Kg)
300.000
250.000
200.000
150.000
100.000
50.000
2003
2002
2001
2000
1999
1998
1997
1996
1995
1994
1993
0
Value (US$ )
Quantity (Kg)
1993
309.461
1994
180.058
1995
194.647
1996
92.851
1997
155.428
1998
156.633
1999
58.721
2000
115.426
2001
156.976
2002
133.591
2003
52.394
Source :1993-2003 Fishery Statistics, Turkish Statistics Institute.
Years
Quantity (Kg)
Value (US$)
Figure 4. The quantity and economical value of exported sharks in Turkey.
The production of sharks in Turkey is variable, but it provides relatively
important income as most of it is exported. SPAGNOLO (1999) stated that sharks have
a wide range of uses and the Mediterranean markets are the most important in absolute
terms. He also pointed out that shark liver is used as a raw material for the production of
pharmaceutical products and the cartilage is used by the same industry for its curative
properties.
In conclusion, it is worthwhile to point out that the main fishing areas in
Turkey for the sharks are the Black Sea and North Aegean Sea. Although sharks are
weakly consumed in Turkey, there are some potentialities to develop internal markets,
pending on stock assessments are undertaken.
85
References
ACARA, A., 1992. Economy of Fishery products change of production, quantity and
price of 1985-1991. (SPO) State Planning Organization of Turkey (in Turkish) pp
203.
ACARA, A., COSKUN, F., PATRONA, K., 1993. Economy of Fishery products
change of production, quantity and price of 1992. (SPO) State Planning Organization
of Turkey, pp 14 (in Turkish).
ACARA, A., 1996. Economy of Fishery products change of production, quantity and
price of 1995. (SPO) State Planning Organization of Turkey, pp 19.
ACARA, A., BAYRAK, M., TASER, B., KUSHAN, S., 1998. Economy of Fishery
products change of production, quantity and price of 1996. (SPO) State Planning
Organization of Turkey.
GOZGOZOGLU, E., ERTAS, S., ERBAS, S., DURU, D., KUSHAN, S., DEVECI, S.,
SENEL, G., 2004. Economy of Fishery products change of production, quantity and
price of 2001-2002. Ministry of Agriculture and Rural Affairs of Turkey, pp 79 (in
Turkish).
GOZGOZOGLU, E., ERTAS, S., ERBAS, S., DURU, D., MALTAS, O. KUSHAN, S.,
DEVECI, S., 2005. Economy of Fishery products change of production, quantity and
price of 2003. Ministry of Agriculture and Rural Affairs of Turkey, pp 82 (in
Turkish).
KABASAKAL, H., 1998. Shark and ray fisheries in Turkey. Shark News 11, page 8.
KABASAKAL, H., 2003. Historical and contemporary of sharks from the Sea of
Marmara, Turkey. ANNALES, Ser. Hist. Nat. 13 (1), 1-12.
KABASAKAL, H., KABASAKAL, E., 2004. Sharks captured by commercial fishing
vessels off the coast of Turkey in the Northern Aegean Sea. ANNALES, Ser. hist. nat.
14 (2), 171-180.
KENCE, A., BILGIN, C. C., 1996. Vertebrate species list of Turkey. Project of Fauna
Database of Turkey. State Planning Organization and the Scientific & Technological
Research Council of Turkey (in Turkish).
KUTAYLIGIL, N., BILECIK, N., 1998. Studies on a Shark Species, Picked Dogfish
(Squalus acanthias L.) Distirubited along the Anatolian Littoral Zones in the Black
Sea. Ministry of Agriculture and Rural Affairs of Turkey, Seafood Research Institute,
Publication Series B (2), pp 73 (in Turkish).
SENEL, G., ATIK, F., BAYRAK, M., TASER, B., KUSHAN, S., SAYGIN, S.,
DEVECI, S., 1999. Economy of Fishery products change of production, quantity and
price of 1997. (SPO) State Planning Organization of Turkey, pp 79 (in Turkish).
SENEL, G., ATIK, F., BAYRAK, M., TASER, B., KUSHAN, S., SAYGIN, S.,
DEVECI, S., 2000. Economy of Fishery products change of production, quantity and
price of 1998. (SPO) State Planning Organization of Turkey, pp 81(in Turkish).
SENEL, G., ATIK, F., ERBAS, S., ERTAS, S., GOZGOZOOLU, E., DURU, D.,
KUSHAN, S., SAYGIN, S.,DEVECI, S., 2001. Economy of Fishery products change
of production, quantity and price of 1999. (SPO) State Planning Organization of
Turkey (in Turkish).
86
SENEL, G., ATIK, F., ERBAS, S., ERTAS, S., GOZGOZOOLU, E., DURU, D.,
KUSHAN, S., SAYGIN, S., DEVECI, S., 2002. Economy of Fishery products
change of production, quantity and price of 2000. (SPO) State Planning Organization
of Turkey (in Turkish).
SENGOR, G. F., 2005. Effect of ascorbat, citrit and salt on fillets of shark (Squalus
acanthias L.1758) preserved in ice in a cool store. Istanbul University, Research
Foundation Project Report (in Turkish).
SLASTENENKO, E., 1956. The Fishes of the Black Sea Basin Meat and Fish Office,
Istanbul, pp 711 (in Turkish).
DIE, 1970-2003, Prime Ministry of Turkish Statistical Institute (Turkstat) State
Instutute Statistics. Fishery Statistics 1970-2003 (in Turkish).
SPAGNOLO, M., 1999. Shark Utilization, Marketing and Trade In: VANNUCCINI, S.
(Ed.), FAO Fisheries Technical Paper 389.
URL1, http://www.fao.org/fi/statist/statist.asp
87
Proc. of the Int. Workshop on Med. Cartilaginous Fish with Emphasis on South.- East. Med., 14-16 Oct. 06, Istanbul-Turkey
Iago omanensis, A DEEP-SEA SHARK UNDER THE STRESS OF
FISHERIES IN THE GULF OF AQABA (NORTHERN RED SEA)
Albert BARANES
Interuniversity Institute of Marine Sciences,
P.O.Box 469, 88000 - Eilat, Israel
Abstract
Iago omanensis, is caught in the Gulf of Aqaba by hook-and-line, mostly by artisanal
fisheries. It is now obvious that commercial fishery on deep-sea fish of the Gulf of
Aqaba, without a proper management program, will endanger the population of Iago
omanensis. The fisheries in the Gulf of Aqaba harvest mostly females while in the Red
Sea proper, the fisheries impacts mostly on large males.
Key words: Red Sea, Iago omanensis, critical habitat, ecology.
Introduction
In Israel, sharks are “protected animals” by law and it is forbidden to catch or sell them;
also it is “non-Kosher” fish and is not consumed by religious Jewish people. When
illegally caught, in the Mediterranean Sea, sharks are smuggled to the Gaza stripe;
therefore obtaining any fisheries statistic is impossible.
The principal and most pressing problem is that none of the countries bordering
the Red Sea has any kind of control in the form of management measures. Furthermore,
there is a general lack of knowledge of how many species of sharks are found in the
region, and neither what is their ecology.
Iago omanensis, among other species, is caught in the Gulf of Aqaba by hookand-line, mostly by artisanal fisheries. In Jordan, Iago is a commercial fish consumed as
fresh food. Although, commercial fishing in Jordan is of little significance, a gradual
decline of commercial fish production has been observed during the last few years.
Jordan fishermen operate approximately 100 medium and small boats, using hand lines,
traps and gillnets as fishing gears (KHALAF, pers. comm.).
The Egyptian fishermen are operating, in the Gulf of Aqaba, mostly in shallow
coastal water and then do not land I. omanensis.
In the Red Sea proper, small-scale fishing boats are commonly used but in
some places larger fishing vessels with long-range capabilities also take part in the
fishery. Trawlers for shrimps usually harvest Iago population and it is commercialized
as by-catch.
The Red Sea presents a very peculiar pattern of circulation, warm surface
waters (28-30oC) entering the Straits of Bab el Mandeb, are transported to the northern
Red Sea where they cool and become saltier; the thermohaline circulation causes the
88
bottom waters to eventually exit the Red Sea system back to the Indian Ocean
(GOLDSHMIDT et al., 1996).
BARANES and GOLANI (1993) showed that the ichthyofauna inhabiting the
deep-waters of the aphotic zone of the Gulf of Aqaba (and the Red Sea) is primarily a
coral reef fauna that migrated to deeper waters, presenting similar abiotic characteristics
(warm and constant temperature) and provided with a sustainable food web.
Within the frame of a regional research and monitoring project (The Red Sea
Peace Park Program), between 2000 and 2003, a joint team of Israeli and Jordanian
Ichthyologists developed a method for monitoring Coral Reef Fishes. It very soon
appeared that about 83 % of the fish caught by fishermen in the northern Red Sea are
coral reef fishes, mostly not edible.
Our recommendation was to move the coastal fisheries to deeper waters, in
order to protect the coral reef ecosystem and to land more valuable commercial fishes.
According to KHALAF (pers.comm.), one of the side impacts on these new
fisheries grounds was the reduction of the number of a deep-sea shark, I. omanensis, in
the catches.
Materials and Methods
The hound shark, Iago, belongs to the Order Carcharhiniformes, Family Triakidae,
Genus Iago COMPAGNO and SPRINGER, 1971.
Only two species in this genus are known today: Iago omanensis (NORMAN,
1939), known from the Red Sea and the Gulf of Aden (Fig. 1 and Fig. 2), and I. garricki
FOURMANOIR and RIVATON (1979) from the New Hebrides.
Figure 1. A live specimen of Iago omanensis, 510 mm TL.
89
Figure 2. Map of the Gulf of Aqaba, northern part enlarged.
Iago omanensis was reported on the basis of photographs taken at 740 m deep
in the central Red Sea by KLAUSEWITZ and THIEL (1982). BARANES and BENTUVIA (1979) recorded I. omanensis as a rare carcharhinid from the Gulf of Aqaba.
Since then it appears that I. omanensis is a common inhabitant of the deep waters of the
Gulf of Aqaba and numerous works were conducted on its ecology and life history.
BARANES and GOLANI (1993) reported I. omanensis from all depths
sampled in the aphotic zone (150-1500 m).
BARANES (1986) described the reproduction of I. omanensis as a viviparous
development, forming a yolk sac-placenta. The males reach maturity at the size of 310320 mm TL, females at about 400 mm. There are 2 to 6 embryos in each litter. Young
90
are born at about 160 mm. TL. Females get pregnant 6 months after parturition. The
gestation period is about 10-12 months. A female is gravid twice in two years. No
seasonality was found in the mating of this species. The sex ratio of embryos was 1:1 in
more than 1000 gravid females observed. HAMLETT et al. (2002) showed that females
are able to retain sperm, for a long period and without affecting its quality.
WALLER and BARANES (1991) investigated the morphology of I. omanensis
and stated that there is no sexual dimorphism in the anatomy of the skull and the jaw
fixation, therefore males and females can eat the same food items.
In a study conducted between 1989 and 1990, WALLER and BARANES
(1994) collected in trammel nets 630 specimens of I. omanensis for stomach contents
analyses. They concluded that there was no sexual difference in the diet of 630 Iago
omanensis examined. In I. omanensis stomachs examined, 7.5 % were empty.
Cephalopods were the most numerous prey items in the diet, with fish intermediate and
crustaceans, gastropods and polychaetes of minor importance. Mud was present in
96.7 % of non-empty stomachs (probably for buffering the stomach pH or the
neutralization of cephalopod toxins). Offal (vegetables, animal bones, feathers) was
recorded in 44 % of non-empty stomachs. Detritus (plastic, rubber, string, nylon) was
present in 9.8 % of non-empty stomachs.
GOLDSHMIDT et al. (1996) reported the bathyal distribution of I. omanensis
in the Gulf of Aqaba and showed that two distinct groups exist within the population
(Fig. 3).
Figure 3. Bathymetric distribution of Iago omanensis (from GOLDSHMIDT et al.,
1996).
91
When plotting the males and females separately, it appears that most of the
males inhabit the deeper waters, while the females prefer shallower areas (Fig. 4).
Figure 4. Distribution of sexes vs. depth in Iago omanensis.
The authors also confirmed the fact described in previous works that females
are found to outnumber males in catches. The overall sex ratio is usually 8 females: 1
male (Fig. 5)
Figure 5. Total length frequency n= 246 of Iago omanensis in the Gulf of
Aqaba (black: females, white: males).
92
GOLDSHMIDT et al. (1996) described the food web in the aphotic zone of the
Gulf of Aqaba, using qualitative analyses of the stomach contents and the stable carbon
isotopic composition (δ13C) in the tissue of collected organisms. They concluded that
the highest trophic level comprising Muraenesox cinereus and Carcharhinus plumbeus,
is above that of I. omanensis, indicating that the former two species feed on the Iago
population. The authors stated that the low proportions of males in catches were
independent of depth of sampling and geographical locality of collection; no evidence
of cannibalism was observed in I. omanensis and remains of only males were not found
ingested by other sharks feeding in the deep reef zone; probably the smaller size of
males makes them vulnerable to higher predation pressure than females.
Sharks species often segregate by sex (SPRINGER, 1967) and the males are
probably in other areas, or in deeper water. The confirmation of this hypothesis was
obtained when we collected 87 I. omanensis in the Dahlak Archipelago (Eritrea, central
Red Sea), 57 males (250-451 mm) and 30 females (267-459 mm) at a depth of 1570 m.
(BARANES, GOLANI and GOREN, personal communication).
Conclusions
Although fishery statistics are inexistent in the area, it is now obvious that commercial
fishery on deep-sea fish of the Gulf of Aqaba, without a proper management program,
will endanger the population of I. omanensis. The fisheries in the Gulf of Aqaba
harvests mostly females while in the Red Sea proper, the fisheries impacts mostly on
large males.
The balance between shark exploitation in fisheries and shark preservation
must be carefully and continuously monitored. It is of higher importance for sustaining
shark population to learn their life history, their reproductive cycle and their food habits.
Nursery grounds must be declared protected areas. When learning the bathymetrical
distribution of each and every species we shall be able to protect selected areas from
fisheries during mating, spawning and parturition periods.
The need of further investigation on sharks is crucial, and since most of the
species are presenting large territories, regional, multinational, joint fishery
management program are to be developed with full partnership.
References
BARANES, A., 1986. Comparative systematics and reproduction of the carcharhinid
sharks of the northern Red Sea. Ph.D. thesis, Hebrew University of Jerusalem, pp
108.
BARANES, A., BEN-TUVIA, A., 1979. Two rare carcharhinids, Hemipristis elongatus
and Iago omanensis from the northern Red Sea. Isr. J. Zool. 28, 39-50.
BARANES, A., GOLANI, D., 1993. An annotated list of deep-sea fishes collected in
the northern Red Sea, Gulf of Aqaba. Isr. J. Zool. 39, 299-336.
COMPAGNO, L. J. V., SPRINGER, S., 1971. Iago, a new genus of carcharhinid
sharks, with a redescription of Iago omanensis. Fish. Bull. 69, 615-626.
93
FOURMANOIR, P., RIVATON, J., 1979. Poissons de la pente recifale externe de
Nouvelle-Caledonie et des Nouvelles-Hebrides. Cah. Indo-Pac 4, 405-443.
GOLDSHMIDT, O., GALIL, B., GOLANI, D., LAZAR, B., EREZ, J., BARANES, A.,
1996. Food selection and habitat preferences in deep-sea fishes of the northern Red
Sea. In: Uiblein, F., Ott, J., Stachowtisch, M. (Eds): Deep-sea and extreme shallowwater habitats: affinities and adaptations. Biosystematics and Ecology Series. 11, 271298.
HAMLETT, W. C., FISHELSON, L., BARANES, A., HYSELL, C. K., SEVER, D. M.,
2002. Ultrastructural analysis of sperm storage and morphology of the oviducal gland
in the Oman shark, Iago omanensis (Triakidae). Mar. Freshwater Res. 53, 601-613.
KLAUSEWITZ, W.,THIEL, H., 1982. Tiefenwasser und Tiefseefische aus dem Roten
Meer. VI. Uber das Vorkommen des Haifisches Iago omanensis (Norman) und des
Messerzahnaals Muraenesox cinereus (Forsskal). Senckenbergiana Maritima. 14,
227-243.
SPRINGER, S., 1967. Social organization of shark populations. In: GILBERT, P. W.,
MATHEWSON, R. F., RALL, D. P. (Eds), Sharks, Skates and Rays. Baltimore: John
Hopkins University Press., pp 149-174.
WALLER,G. N. H., BARANES, A., 1991. Chondrocranium morphology of northern
Red Sea triakid sharks and relationship to feeding habits. J.Fish Biol. 38, 715-730.
WALLER, G. N. H., BARANES, A., 1994. Food of Iago omanensis, a deep water shark
from the northern Red Sea. J. Fish Biol. 45, 37-45.
94
Proc. of the Int. Workshop on Med. Cartilaginous Fish with Emphasis on South.- East. Med., 14-16 Oct. 06, Istanbul-Turkey
CARTILAGINOUS FISHES OF THE MEDITERRANEAN
COAST OF ISRAEL
Daniel GOLANI
Department of Evolution, Systematics and Ecology
The Hebrew University of Jerusalem
91904 Jerusalem, Israel
Abstract
The Mediterranean ichthyofauna of Israel numbers a total of 57 cartilaginous species:
31 sharks, 25 skates and rays and only a single Chimaera species. Only one species
Himantura uarnak (Forsskål, 1775) is of Red Sea origin (Lessepsian migrant). The
west-east gradient of species number, known throughout the entire Mediterranean
ichthyofauna, is echoed in cartilaginous species, where only 65.5 % of the
Mediterranean ichthyofauna is found in Israel. The annual catch of cartilaginous
species in the last few decades ranges between 28-111 tons, constituting only 0.9-2.8 %
of the total catch. Due to their low catch and low commercial value in Israel, there are
very few local studies of the biology and ecology of these species. However their
importance in the well-being of the ecosystem justifies more intensive studies of
cartilaginous fishes, in order to formulate effective conservation and management
policies.
Key words: Israel coast, Levantine basin, Lessepsian migration.
Cartilaginous fish constitute an important component in all marine ecosystems. Since
some cartilaginous fish are target species of commercial fishery, it is essential to study
their biology, ecology and the impact of fishery and other anthropogenic factors on their
exploited stocks.
Conservation of cartilaginous species is an acute issue worldwide. The high
demand for shark fins in the markets of the Far East, as well as their low reproductive
rate, places many sharks in the list of endangered species.
In order to further understand the global distribution and population dynamics
of cartilaginous fish, regional studies must be conducted. Therefore, a primary research
priority is the compilation of an inventory list of the cartilaginous species of the
Mediterranean coast of Israel and comparing this list with that of the entire
Mediterranean. For the purposes of this compilation, the work of QUIGNARD and
TOMASINI (2000) was used regarding cartilaginous fishes of the entire Mediterranean
and that of GOLANI (2005) regarding the coast of Israel.
When one examines the ichthyofauna of the entire Mediterranean, one sees a
clear west-east gradient of the number of species; 664 fish species have been recorded
in the Mediterranean, of which only 402 (60.5 %) are in the Israeli coast. However, this
rate is misleading and is actually more moderate, due to the influx of Lessepsian
95
migrants that entered the Mediterranean via the Suez Canal. To date, there are 62
Lessepsian fish species occupying the eastern Mediterranean basin (GOLANI and
SONIN, in press). As for indigenous Mediterranean fish species, only 52.2% are found
also in the eastern basin (see Table 1).
This west-east gradient of number of species is echoed in Cartilaginous
species; out of 87 Mediterranean species, 57 (65.5 %) are found in the Israeli coast and
out of 55 shark species, 31 (56.4 %) are found in the eastern basin. However, this value
may be an overestimation, since QUIGNARD and TOMASINI (2000) included in their
list several doubtful and questionable records (including Carcharhinus melanopterus,
Sphyrna tudes, Centrophorus uyato, etc.). As for Batoidea, 25 (83.3 %) species are
found in Israel out of 30 in the entire Mediterranean. The single Chimaera species
(Chimaera monstrasa) is distributed throughout the Mediterranean.
Table 1. Number of fish species in the Mediterranean coast of Israel as compared to that
of the entire Mediterranean
All fish species
Med. Indigenous only
Cartilaginous
Sharks
Skates and Rays
Chimaera
Entire
Mediterranean
664
664
87
55
30
1
Coast of Israel
%
402
340
57
31
25
1
60.5
51.2
65.5
56.4
83.3
100.0
Very little is known about the abundance of cartilaginous species, for two main
reasons. Firstly, there is some confusion as to the taxonomy of these species. Secondly,
the catch of all cartilaginous species is lumped together in fishery statistics which are
the main source of information on these species.
The paucity of biological studies of cartilaginous fish in Israel is due to a
certain extent to the low esteem and therefore the low price given them in local markets.
The low demand for cartilaginous fish in Israel stems mainly from the fact that their
consumption is forbidden for observant Jews, since these fish are not kosher. According
to the Jewish religion, only fish with scales are kosher or ritually permitted for eating.
Despite the fact that sharks have scales, the definition of scales by Jewish religious
authorities differs from that of ichthyologists. The laws of Kashrut or keeping kosher
provide that a fish scale must be big enough to be discernible by the naked eye and also
should be easily detachable. The placoid scales of sharks do not meet these criteria.
Therefore, most of the sharks, skates and rays caught along the Israeli Mediterranean
coast are sold to non-Jewish communities at a rather low price.
Cartilaginous fishes are considered to be a by-catch by local Israeli fishermen
who catch them mainly by trawl and bottom long-line and, to a lesser extent, in purse
seine and trammel nets. The total annual catch of Mediterranean cartilaginous species in
96
Israel for the years 1980-2004 varied greatly between 28 to 111 tons, constituting only
0.9-2.8 % of the total catch (DEPARTMENT OF FISHERIES, 1981-2005).
Table 2 reveals the list of the cartilaginous fish of the Mediterranean coast of
Israel with a general classification of each species' abundance.
Table 2. List of cartilaginous species from the Mediterranean coast of Israel. R – Rare;
P—Prevalent; C—Common
SELACHII
HEXANCHIDAE
ODONTASPIDIDAE
LAMNIDAE
CETORHINIDAE
ALOPIIDAE
SCYLIORHINIDAE
TRIAKIDAE
CARCHARHINIDAE
SPHYRNIDAE
DALATIIDAE
OXYNOTIDAE
CENTROPHORIDAE
SQUALIDAE
SQUATINIDAE
BATOIDAE
PRISTIDAE
TORPEDINIDAE
RHINOBATIDAE
Heptranchias perlo (Bonnaterre, 1788)
Hexanchus griseus (Bonnaterre, 1788)
Carcharias taurus Rafinesque, 1810
Odontaspis ferox (Risso, 1810)
Carcharodon carcharias (Linnaeus, 1758)
Isurus oxyrinchus Rafinesque, 1810
Lamna nasus (Bonnaterre, 1788)
Cetorhinus maximus (Günnerus, 1765)
Alopias superciliosus (Lowe, 1839)
Alopias vulpinus (Bonnaterre, 1788)
Galeus melastomus Rafinesque, 1810
Scyliorhinus canicula (Linnaeus, 1758)
Mustelus asterias Cloquet, 1821
Mustelus mustelus (Linnaeus, 1758)
Carcharhinus altimus (Springer, 1950)
Carcharhinus brevipinna (Müller and Henle, 1839)
Carcharhinus limbatus (Valenciennes, in Müller and Henle, 1839)
Carcharhinus obscurus (Lesueur, 1818)
Carcharhinus plumbeus (Nardo, 1827)
Prionace glauca (Linnaeus, 1758)
Sphyrna zygaena (Linnaeus, 1758)
Etmopterus spinax (Linnaeus, 1758)
Dalatias licha (Bonnaterre, 1788)
Oxynotus centrina (Linnaeus, 1758)
Centrophorus granulosus (Bloch and Schneider, 1801)
Squalus acanthias Linnaeus, 1758
Squalus blainvillei (Risso, 1826)
Squatina aculeata Dumeril in Cuvier, 1817
Squatina oculata Bonaparte, 1840
Squatina squatina (Linnaeus, 1758)
Pristis pectinata Latham, 1794
Torpedo marmorata Risso, 1810
Torpedo nobiliana Bonaparte, 1835
Torpedo torpedo (Linnaeus, 1758)
Rhinobatos cemiculus Geoffroy Saint-Hilaire, 1817
97
P
P
R
R
R
P/R
R
R
P
R
C
C
R
C
R
P
R
C
C
R
P
C
R
C/P
C
C
P
R
P
R
R
C
R
C
P
Tablo 2. (Cont.)
RAJIDAE
DASYATIDAE
GYMNURIDAE
MYLIOBATIDAE
RHINOPTERIDAE
MOBULIDAE
HOLOCEPHALI
CHIMAERIDAE
Rhinobatos rhinobatos (Linnaeus, 1758)
Dipturus oxyrinchus (Linnaeus, 1758)
Raja asterias Delaroche, 1809
Raja clavata Linnaeus, 1758
Raja miraletus Linnaeus, 1758
Raja montagui Fowler, 1910
Raja radula Delaroche, 1809
Raja undulata Lacépède, 1802
Dasyatis centroura (Mitchill, 1815)
Dasyatis chrysonota (Smith, 1828)
Dasyatis pastinaca (Linnaeus, 1758)
Dasyatis tortonesei Capapé, 1975
Himantura uarnak (Forsskål, 1775)
Pteroplatytrygon violacea (Bonaparte, 1832)
Taeniura grabata (Geoffroy St-Hilaire, 1817)
Gymnura altavela (Linnaeus, 1758)
Myliobatis aquila (Linnaeus, 1758)
Pteromylaeus bovinus (Geoffroy St-Hilaire, 1817)
Rhinoptera marginata (Geoffroy St-Hilaire, 1817)
Mobula mobular (Bonnaterre, 1788)
Chimaera monstrosa Linnaeus, 1758
C
C
R
C
C
R
R
R
R
C/P
C
P
P
R/P
C/P
P
C/P
C/P
C
R
C
Knowledge of the biology and ecology of cartilaginous fish along the coast of
Israel is partial. There have been a few studies of Centrophorus granulosus and other
deep-water species (GILAT and GELMAN, 1984; PISANTY and GOLANI, 1995;
GOLANI and PISANTY, 2000) and several taxonomical studies (BARANES, 1973;
GOLANI and CAPAPÉ, 2004). PISANTY and GOLANI (1995) and GOLANI and
PISANTY (2000) showed that C. granulosus is the most abundant shark at depths of
200-400 m, with a sex ratio of 1 male to 4.5 females. At depths of 500-800 m males
dominate while juveniles inhabit depths of 1400-1500 m with an equal ratio of males to
females. The most abundant shark species at these depths was found to be Galeus
melastomus with females overwhelming males by a ratio of 1 male to 21 females
(GOLANI, unpublished data). BEN-TUVIA (1977) reported large catches of two shark
species Carcharhinus plumbeus and C. obscurus outside the openings connecting the
Bardawil Lagoon (northern Sinai) to the Mediterranean; in this lagoon, these sharks are
abundant particularly in winter, when their primary fish prey species Dicentrarchus
labrax and Sparus aurata commence spawning in November and December and return
to the lagoon in March and April.
Regarding cartilaginous Lessepsian migrants, only a single such species has
been recorded: the Spotted or Forsskål's stingray Himantura uarnak. The presence of
another Indo-Pacific shark, Carcharhinus melanopterus, in the Mediterranean has been
recorded by TORTONESE (1951). But it should be noted that this record originated in
98
Egypt, where the source of the specimens could be from the Red Sea; in addition, no
specimens were preserved for confirmation. Furthermore, C. melanopterus bears a
superficial resemblance, especially its black fin tips, to the indigenous Carcharhinus
brevipinna. However, the occurrence of C. melanopterus in the Mediterranean has been
repeatedly cited in major works. BEN-TUVIA (1978) erroneously reported
Carcharhinus brevipinna as a Lessepsian migrant despite its being an indigenous
Mediterranean species.
Further studies of cartilaginous fish in the Levant are of prime importance. The
question remains, whether the apparent low abundance of these fish in the eastern
Mediterranean is due to the fact that data has been obtained from fishery statistics or
whether this is a true case of scarcity. Only direct studies on the abundance of these
species in the Levant will reveal a more accurate picture, when complemented by
studies on such biological aspects as growth rate, feeding habits and reproduction, etc.
These studies will provide tools to aid in making rational decisions as to conservation of
cartilaginous species in the Levant.
References
BARANES, A., 1973. Taxonomy and behaviour of the genera Mustelus and Triaenodon
(Triakidae, Pisces) of the Mediterranean and Red Sea. M.Sc. Thesis. The Hebrew
University of Jerusalem, Jerusalem, pp 108.
BEN-TUVIA, A., 1977. Report on the fisheries research in the Bardawil Lagoon for the
years 1975-1976. Heb. Univ. Jerusalem, pp 35. (mimeo, in Hebrew)
BEN-TUVIA, A., 1978. Immigration of fishes through the Suez Canal. Fish. Bull. 76,
249-255.
DEPARTMENT OF FISHERIES, 1981-2005. Israel Fisheries in Figures (years 19802004). Min. Agricul. Tel-Aviv. (24 annual reports).
GILAT, E., GELMAN, A., 1984. On the sharks and fishes observed using underwater
photography during a deep-water cruise in the eastern Mediterranean. Fish. Res. 2,
257-271.
GOLANI, D., 2005. Checklist of the Mediterranean fishes of Israel. Zootaxa, 947, 1-90.
GOLANI, D., CAPAPÉ, C., 2004. First record of the Blue stingray, Dasytis chrysonota
(Smith, 1828) (Chondrichthyes: Dasyatidae), off the coast of Israel (eastern
Mediterranean). Acta Adriatica 45, 107-113.
GOLANI, D., PISANTY, S., 2000. Biological aspects of the Gulper shark, Centrphorus
granulosus (BLOCH & SCHNIEDER, 1801), from the Mediterranean coast of Israel.
Acta Adriatica 41, 71-78.
GOLANI, D., SONIN, O., in press. The Japanese threadfin (Nemipterus japonicus), a
new Indo-Pacific fish in the Mediterranean. J. Fish Biol.
PISANTY, S. GOLANI, D., 1995. Vertical distribution of demersal fish on the
continental slope of Israel. In : ARMANTROUT, N. B. (Ed.), Condition of the World
Aquatic Habits. Proc. World Fish. Con. Theme 1. Oxford & IBH Pub. Com. New
Delhi, pp 386-395.
99
QUIGNARD, J. P., TOMASINI, J. A., 2000. Mediterranean fish biodiversity. Biol.
Mar. Medit. 7 (3), 1-66.
TORTONESE, E., 1951. I. Caratteri biologici del Mediterraneo orientale e i problemi
relative. Attualità Zoologiche 7, 207-251.
100
Proc. of the Int. Workshop on Med. Cartilaginous Fish with Emphasis on South.- East. Med., 14-16 Oct. 06, Istanbul-Turkey
ELASMOBRANCH RESEARCH IN SLOVENIA: STATE OF THE ART
Borut MAVRIČ1, Robert TURK2 and Lovrenc LIPEJ1
1
2
Marine Biology Station Piran, NIB, Slovenia
Institute of Republic of Slovenia for Nature Conservation Piran, Slovenia
Abstract
In the Slovenian part of the Adriatic Sea elasmobranch research is almost totally
neglected in favour of the study of commercially more important bony fishes (e.g.
swordfish). Elasmobranch research is more or less connected to an individual interest of
a small number of ichthyologists and marine biology enthusiasts rather than to
organized research interest. Up to date, 34 elasmobranch species (20 sharks and 14
Batoids) have been recorded in the Slovenian coastal sea. However, among them only
few are rather common in the area. In recent years research in Slovenia has been
focused on different topics such as: feeding ecology of Mustelus punctulatus and M.
mustelus, increased occurrence of basking sharks (Cetorhinus maximus) and occurrence
of juvenile sandbar shark specimens (Carcharhinus plumbeus) in the area, ecology and
feeding habits of violet stingray (Pteroplatytrigon violacea) and others.
Key words: North Adriatic Sea, Slovenian coast.
Introduction
In the Adriatic area, elasmobranch research is almost totally neglected in favour of the
study of commercially more important bony fishes. This is true for Slovenia, as well,
where there is still a huge lack in all aspects of elasmobranch research. This is more or
less connected to an individual interest of a small number of ichthyologists and marine
biology enthusiasts rather than to organized research interest. The knowledge on sharks
and rays is still more or less connected with occasional captures by fishermen.
The sea of Slovenia covers the southern part of the Gulf of Trieste, which is the
northernmost part of both the Adriatic and the Mediterranean seas. It is a shallow semienclosed gulf with a maximum depth of ca. 33 m in waters off Piran. Slovenian
coastline is approximately 46 km long. The area is characterized by the greatest tidal
differences (semidiurnal amplitudes approach 30 cm) and the lowest winter
temperatures (below 10oC) in the Mediterranean Sea (BOICOURT et al., 1999).
Up to date, 34 elasmobranch species (20 sharks and 14 batoids) have been
recorded in the Slovenian coastal sea (LIPEJ et al., 2004). However, among them only
few are rather common in the area. Five species of sharks: nursehound (Scyliorhinus
stellaris), lesser spotted cat shark (Scyliorhinus canicula), piked dogfish (Squalus
acanthias), smooth-hound (Mustelus mustelus) and black-spotted smooth-hound
(Mustelus punctulatus), and seven ray and skate species: marbled electric ray (Torpedo
marmorata), common stingray (Dasyatis pastinaca), common eagle-ray (Myliobatis
101
aquila), bull ray (Pteromylaeus bovinus), starry ray (Raja asterias), thornback ray (Raja
clavata) and brown ray (Raja miraletus) should be considered as frequent in the area.
Some other species are only occasionally visiting the area, whereas the majority of
species were only rarely sighted or captured in waters off Slovenia (LIPEJ et al., 2004).
Materials and Methods
Highlights of research
The most common shark species in the Slovenian coastal area are M.
punctulatus and M. mustelus. A recent research on the ecology of those species revealed
that they are both occurring in mixed schools (Fig. 1). Additionally, the analysis of their
stomach content showed that they are feeding on the same assemblage of benthic
invertebrates, mainly bivalves, clupeids and mantis shrimps (Squilla mantis). Due to
such results, certain doubts are arising on the validity of the status of M. punctulatus as
a distinct species.
30
M. mustelus
M. punctulatus
No. specimens
25
20
15
10
5
141-150
131-140
121-130
111-120
101-110
91-100
81-90
71-80
61-70
51-60
41-50
0
size range (cm)
Figure 1. Size range distribution of two mustelid shark species, caught in the
Slovenian coastal waters in 2003-2004.
The basking shark (Cetorhinus maximus) occurrence in the Slovenian coastal
sea deserves a proper attention. During last decades, the frequency of sightings (and
captures) of basking sharks in the Adriatic Sea with particular emphasis at the
102
northernmost part drastically increased. In the Slovenian coastal sea two juvenile
basking sharks were accidentally caught in the waters off Piran in 2000 (LIPEJ et al.,
2000a). The first one has been entrapped in the special net for small sharks (e.g. smooth
hounds), whereas the other was entangled in the bottom net for flatfish. In the very next
year, a group of ten sharks were monitored while grazing in the Slovenian coastal sea
over a month in spring. There are evidences of huge specimens, almost 9.50 m in
length, but also cases of some very small specimens, measuring below 3 m and even
below 2.5 m (LIPEJ et al., 2004).
Figure 2. Grazing basking shark from a group of ten individuals observed off Slovenian
coast during a month long period in 2000 (Photo: C. Mlinar).
It is not yet clear, what is the main reason of a sudden increase of evidence.
Certain authors such as ZUFFA et al. (2001) postulated three possible explanations for
the unusual occurrence of basking sharks in northern and central Adriatic Sea.
According to them, this event could be explained by climate changes, changes in
zooplankton abundance or some unknown aspects of basking sharks metabolism and/or
behaviour.
Recently, we witnessed the increased abundance of another elasmobranch
species, the violet stingray (Pteroplatytrigon violacea). The very first record of this
species has been reported by MAVRIČ et al. (2004) for the waters of Slovenia. Since
then, the pelagic stingray has been regularly caught by fishermen. The preliminary
research on its feeding habits revealed a diverse food spectrum, consisting mainly on
Cepola rubescens and clupeids (Fig. 3) (MAVRIČ et al., 2004). The increasing number
of pelagic stingrays in the area offers the possibility to investigate this species more
accurately, in order to get more precise data on its diet and role in the food web. At the
103
very same time, the feeding habits of the eagle ray (Myliobatis aquila) and the bull ray
are investigated. Both species are regularly occurring in the area in high numbers.
Figure 3. Prey items found in stomachs of pelagic stingray (Figure by T. Makovec).
Beside the previously mentioned juvenile basking sharks there were another
two distinct juvenile elasmobranch specimens of Carcharhinus plumbeus caught in
Slovenian area in 2000. In October 2000 a specimen of sandbar shark has been caught
in gillnet called »cagnara«, a fishing gear for small cartilaginous fish. This was the first
ever record of this species in Slovene coastal waters. The second specimen was caught
10 days later in the trammel net called »passarela« used for fishing flatfish (LIPEJ et
al., 2000b). These juveniles together with a record of some neonatal specimens caught in
northern Adriatic imply that northern Adriatic might be a nursery area for this rather
rare (or neglected) shark species in the Adriatic Sea.
Threats
Since elasmobranches are more vulnerable to fishery than other fishes high
measure of caution should be taken when exploiting them. Elasmobranches in Slovenian
waters are usually not exposed to targeted fishery. Fishing effort is dedicated only to
smooth-hounds (Mustelus spp.) and piked dogfish (S. acanthias). According to some
fishermen, less than 5 tonnes of those shark species are caught per year.
Elasmobranches are thus having a rather negligible relative importance in Slovenian
fisheries. Unplanned capture known as by-catch represents one of the most damaging
impact on elasmobranch populations in Slovenian coastal waters. Thresher sharks
(Alopias vulpinus) are occasionally caught by fishermen and in certain cases juvenile
specimens of basking shark were captured in bottom nets, as previously mentioned. The
104
same is true for many stingrays, eagle rays and bull rays, which are regularly caught in
pelagic trawls and discarded at sea by fishermen.
Although the Slovenian sea covers only a small portion of the Adriatic Sea, the
big game is practiced in the area, as well. This impact seems to be a serious threat to
certain shark species such as the Thresher shark and Blue shark (Prionace glauca). This
is even more concerning as the northern Adriatic represents a nursery area for both
species.
During last decade many cases of illegal trading with shark jaws are known in
Slovenia. Generally, confiscated jaws belonged to several tropic shark species. There is
a good cooperation between Marine Biology Station and the Ministry of Environment,
who is involved in CITES.
Conservation
The decline in the number of elasmobranches calls for urgent investigation into
their status. Despite only small portion of the Adriatic Sea belongs to Slovenia, a
relatively high number of elasmobranchs have been till now reported for the area. This
shows importance of Slovenian area in elasmobranch research and conservation. As
there are still some cases of captures of shark species, listed in the IUCN list of
endangered animals, such as the basking shark and the great white shark (Carcharodon
carcharias), some conservation measures should be put into practice. There is also a
critical need, prior to conservation, for biological information on the life history of
many elasmobranch species in order to better assess the impact of fisheries on these top
predators. Their role in structuring biodiversity should as well be assessed and this
cannot be done without a basic knowledge on elasmobranch biology and ecology.
References
BOICOURT, W. C., KUZMIĆ, M., HOPKINS, T. S., 1999. The Inland Sea: Circulation
of Chesapeake Bay and the Northern Adriatic. In: MALONE T. C., MALEJ A.,
HARDING L. W. JR., SMODLAKA N., TURNER R. E. (Ed.): Ecosystems at the
Land-Sea Margin: Drainage Basin to Coastal Sea. Coastal and Estuarine Studies 55,
81-129.
LIPEJ, L., MAKOVEC, T., SOLDO, A., ŽIŽA, V., 2000a. Records of the Sandbar shark
Carcharhinus plumbeus, (Nardo, 1827) in the Gulf of Trieste (Northern Adriatic).
Annals Istr. Med. Studies 10 (2), 199-206.
LIPEJ, L., MAKOVEC, T., ORLANDO BONACA, M., ŽIŽA, V., 2000b. Occurrence
of the Basking shark, Cetorhinus maximus (Günnerus, 1765), in the waters off Piran
(Gulf of Trieste, Northern Adriatic). Annals Istr. Med. Studies 10 (2), 211-218.
LIPEJ, L., DE MADDALENA, A., SOLDO, A., 2004. Sharks of the Adriatic sea,
Annales Majora, Koper, 253 pp.
MAVRIČ, B., JENKO, R., MAKOVEC, T., LIPEJ, L., 2004. On the occurrence of the
pelagic stingray, Dasyatis violacea (Bonaparte, 1832), in the Gulf of Trieste
(Northern Adriatic). Annals Istr. Med. Studies 14 (2), 181-186.
105
ZUFFA, M., SOLDO, A., STORAI, T., 2001. Preliminary observations on abnormal
abundance of Cetorhinus maximus (Gunnerus, 1765) in the central and northern
Adriatic Sea. Annals Istr. Med. Studies 11 (2), 185-192.
106
Proc. of the Int. Workshop on Med. Cartilaginous Fish with Emphasis on South.- East. Med., 14-16 Oct. 06, Istanbul-Turkey
THE GULF OF GABÈS: A SPOT FOR THE MEDITERRANEAN
ELASMOBRANCHS
Mohamed Nejmeddine BRADAÏ1, Bechir SAIDÏ1,
Samira ENAJJAR1 and Abderrahmen BOUAIN2
1
Institut national des sciences et technologies de la mer, Centre de Sfax, BP 1035, 3018 Sfax, Tunisia.
E-mail : mednejmeddine.bradai@instm.rnrt.tn
2
Faculté des Sciences de Sfax, BP 802, 3018 Sfax, Tunisia.
Abstract
Among the Mediterranean elasmobranchs, 62 species occurred along the Tunisian
coasts. The elasmobranchs fauna of Tunisia included 33 sharks and 29 rays representing
about 19 % of Tunisian ichthyofauna. Twenty-three sharks and 21 rays are recorded in
the gulf of Gabès, the most important fishing area.
In Tunisia, elasmobranchs constitute about 2 % (2000 Tones/an) of national
fish production. They are captured mainly by the bottom trawl, gillnets and longlines.
The most abundant fishing zone is the gulf of Gabès from which about 70 % of Tunisian
production is landed. Mainly 5 sharks and 7 rays are landed throughout the year and
have an economic value. Several other species are landed along the year as by-catch of
fisheries. Pelagic species (Isurus oxyrinchus, Alopias vulpinus and Carcharodon
carcharias) were frequently captured by tuna trap.
Literature and new investigations along the Tunisian coasts, mainly in the gulf
of Gabès, suggest that many species found favorable environmental conditions to
develop and reproduce in the area, which constitutes nursery for some of them.
Key words: Tunisia, gulf of Gabès, elasmobranchs, nurseries.
Introduction
The Mediterranean elasmobranchs consist of about 1/10 of the total number of species
in the world and they are represented with 84 species (SERENA, 2005). They are found
in various habitats, from the coastal lagoons to the abyssal grounds. Although,
elasmobranchs border various habitats, they migrate to rather specific places when they
give birth or lay eggs (SPRINGER, 1967). These areas are geographically discrete parts
where the gravid females deliver their young or deposit their eggs and where their
young spend their first weeks, months or years. These areas are usually located in
shallow, energy rich coastal zones where the young find abundant food and have little
predation by large sharks (CASTRO, 1993).
The present paper deals with the status of elasmobranch species off Tunisian
coasts and mainly off gulf of Gabès coasts.
107
Materials and Methods
This work is based on (1) the analysis of the ichthyological knowledge available for the
Tunisian elasmobranchs (QUIGNARD and CAPAPE, 1971, 1972; CAPAPE, 1975;
1987; CAPAPE et al., 1979; CHAKROUN, 1966; NAJAI, 1980), (2) surveying
campaigns (using the INSTM’s oceanographic vessel and commercial fishing fleet) and
(3) visits to main landing points mainly in the gulf of Gabès (Fig. 1).
As sampling has various goals, it includes species and sex determination,
measurements (TL mm and claspers length for males) and weighing. Several specimens
of both sexes were dissected to examine the genital tract for maturity stages. The
oocytes, the embryos and the fully developed fetuses were removed from the ovaries
and the uteri of female genital tracts and then measured and weighted.
Figure 1. Map of Tunisian coasts
108
Results
Diversity
The Mediterranean basin is known as one of the world-wide marine regions
where biodiversity is high. Its ichthyofauna includes 664 species of fish of which 84 are
elasmobranchs (SERENA, 2005). These elasmobranchs fauna compound endemic,
Atlantic, cosmopolitan and Lessepsian migrants’species. Mediterranean elasmobranchs
are mainly coastal (80%). Among the Mediterranean elasmobranchs, 62 species
occurred along the Tunisian coasts (BRADAI et al., 2002; BRADAI et al., 2004). The
elasmobranchs fauna of Tunisia included 33 sharks and 29 rays representing about 19%
of Tunisian ichthyofauna (BRADAI et al., 2004). Among the 33 sharks, 23 species are
recorded in the gulf of Gabès (BRADAI et al., 2002). Among the 29 rays, 21 species
occurred along the gulf of Gabès. Of the 33 sharks cited along the Tunisian coasts, we
observed 27 species from which three are recorded only one time during our
investigations. Six sharks are cited in literature and not observed during last decade
(Table 1). Among the 29 rays, we observed only 21 species since 1990 (Table 2).
Table 1. Sharks recorded in Tunisian coasts
Species
Heptranchias perlo
Hexanchus griseus
Squalus blainvellei
Squalus acanthias
Dalatias licha
Etmopterus spinax
Oxynotus centrina
Centrophorus granulosus
Squatina aculeata
Squatina oculata
Squatina squatina
Alopias vulpinus
Cetorhinus maximus
Carcharodon carcharias
Isurus oxyrhinchus
Lamna nasus
Sphyrna zygaena
*
*
*
*
*
*
*
*
*
*
*
*
*
-
Species
Carcharias taurus
Odontaspis ferox
Scyliorhinus canicula
Scyliorhinus stellaris
Galeus melastomus
Galeorhinus galeus
Mustelus asterias
Mustelus mustelus
Mustelus punctulatus
Carcharhinus brevipinna
Carcharhinus melanopterus
Carcharhinus plumbeus
Carcharhinus falciformis
Carcharhinus limbatus
Carcharhinus obscurus
Prionace glauca
*Regularly observed, ** Observed only one time, - Cited in literature and not observed.
109
*
*
*
*
*
*
*
*
*
*
**
**
**
*
Table 2. Rays recorded in Tunisian waters.
Species
Dasyatis pastinaca
Dasyatis tortonesei
Dasyatis centroura
Dasyatis chrysonota
Peroplatytrygon violacea
Taeniura grabata
Torpedo marmorata
Torpedo torpedo
Torpedo nobiliana
Rhinobatos rhinobatos
Rhinobatos cemiculus
Myliobatis aquila
Pteromylaeus bovinus
Mobula mobular
Gymnura altavela
Species
Raja clavata
Raja radula
Raja miraletus
Raja asterias
Raja montagui
Raja brachyura
Raja polystigma
Raja africana
Dipturus oxyrinchus
Leucoraja fullonica
Leucoraja circularis
Leucoraja naevus
Leucoraja melitensis
Rostroraja alba
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
* Regularly observed, ** Observed only one time, - Cited in literature and not observed
Landing
In Tunisia, elasmobranchs constitute about 2 % (2000 Tones/an) of national
fish production (ANONYMOUS, 2004). The most abundant fishing zone is the gulf of
Gabès from which about 70% of Tunisian production is landed (Fig. 2). Mainly 5 sharks
and 7 rays are landed throughout the year and have an economic value (Sharks:
Mustelus mustelus, M. punctulatus, Carcharhinus plumbeus, Squalus blainvillei and
Scyliorhinus canicula; Rays: Rhinobatos cemiculus, R. rhinobatos, Dasyatis pastinaca,
D. tortonesei, Pteromylaeus bovinus, Torpedo torpedo and Raja clavata).
110
2500
Tunisia
gullf of Gabès
Production (T)
2000
1500
1000
500
0
1995 1996 1997 1998 1999 2000 2001 2002 2003 2004
Figure 2. Elasmobranch landings in Tunisia and gulf of Gabès during the period 19952004.
In the Gabès gulf, the targeted species are M. mustelus, M. punctulatus, C.
plumbeus, R. cemiculus and R. rhinobatos. Several other species are landed along the
year in important quantities such as Dasyatids, S. blainvillei, P. bovinus, Scyliorhinids
but constitute the by-catch of fisheries.
Commercial catches of targeted species such as C. plumbeus and Mustelus spp
in the gulf of Gabès are seasonal; they peak in spring-summer when these species move
to shallow water (Fig. 3, 4). Our investigation shows that inshore moving is a regular
annual event, and it is probably linked with annual reproductive cycle.
24
50
Production (T)
Production (T)
60
40
30
20
10
0
18
12
6
0
J F M A M J J A S O N D
J F M A M J J A S O N D
Figure 3. Monthly landing of C. plumbeus.
Figure 4. Monthly landing of Mustelus spp.
Fishing gears in the gulf of Gabès
Along the Tunisian coast, elasmobranchs are mainly caught with bottom
trawls, gillnets and longlines.
111
The bottom trawlnets, with a cod end of 20 mm stretched mesh, were used to
capture shrimps and demersal fishes at depths of 30-100 m. Elasmobranchs were bycatch species. Sandbar sharks were targeted March-July between Djerba Island and
Zarzis by gillnets in polyamide monofilament with a stretched mesh size of 300-400
mm. Gillnets were 1000-3000 m long, set on the sea floor at depths of 10-25 m, and
checked and cleared of catch, or pulled and reset, daily. These special gillnets
“Garracia”, was used only to capture C. plumbeus or Rhinobatids. C. plumbeus were
also captured by pelagic and bottom longlines. Pelagic longlines, used in June-August,
consist of a heavy nylon monofilament mainline, 7-28 km long, connected to buoys by a
10 m buoy line. Twenty-five large hooks (hook size: 00-01) are suspended about every
kilometer, at depths of 30-100 m. Bottom longlines, used in August-October, consist of
a heavy nylon monofilament (1.5-3 km long) with small hooks, generally 200 (hook
size: 04-05) suspended every kilometer and a single hook per light stick. For both types
of longlines, the hooks were baited with pieces of teleosts such as pilchard and mackerel
or cephalopods such as cuttlefish.
The Smooth-hounds were targeted by special gillnets “Gattatia” from February to June
along the gulf of Gabès coasts. This gillnets was constructed of polyamide
monofilament netting with a stretched mesh size of 120-160 mm. Gillnets were 5001500 m long, set on the sea floor at depths of 10-40 m, and checked and cleared of
catch, or pulled and reset, daily.
By-catch
Several species of sharks and rays of different size, but mainly the juvenile, are
captured incidentally as by-catch in costal fisheries. These categories include mainly
Triakids, Dasyatids, P. bovinus and juveniles of Carcharhinids. Individuals of
Cetorhinus maximus are mainly caught as by-catch along the Tunisian coasts (CAPAPE
et al., 2003; MANCUSI et al., 2005).
The deep fisheries (trawls and longlines) captured incidentally several sharks.
Scyliorhinus canicula, Galeus melastomus, S. blainvillei, Centrophorus granulosus,
Mustelus spp and some rays are common in the catches. Species without commercial
values, such Rajids, are discarded at sea.
Pelagic sharks (Isurus oxyrinchus, Prionace glauca) represent the main bycatch of high-sea fisheries targeting tuna and swordfish.
The pelagic species were also frequently captured by tuna trap. Recent
observations and data available in literature show that three large shark species are
episodically caught in tuna traps: I. oxyrinchus, Alopias vulpinus and Carcharodon
carcharias. From 27 records of C. carcharias along the Tunisian coast, 15 were
registered in the tuna trap of Sidi Daoud.
Critical habitats
Mediterranean Sea offers divers habitats from coastal lagoons to abyssal
grounds. However, little information is known about the presence of nursery area in
Mediterranean Sea. It is possible that parturition occurred in remote areas; for exemple,
neonates of C. plumbeus are captured in Adriatic Sea (COSTANTINI and AFFRONTE,
112
2003) and gravid females off Turkish coast (SIMON CLÒ, pers. comm.). Northern
Tyrrhenian Sea and Southern Ligurian Sea are hypothesized to be nurseries for R.
clavata, S. canicula and G. melastomus (BAINO and SERENA, 2000). However, the
mere presence of gravid females bearing term pups and neonates in an area is not
sufficient to determine a nursery area (CASTRO, 1993). In general, shark nurseries are
areas where gravid females give birth or lay eggs, and where the young spend their first
weeks, months or years (SPRINGER, 1967).
Literature and new investigations along the Tunisian coasts mainly in the gulf of Gabès
suggest that many species found favorable environmental conditions to develop and
reproduce in the area which constitutes nursery for some of them.
The sandbar shark, Carcharhinus plumbeus
The sandbar shark, C. plumbeus, is a medium-sized coastal carcharhinid with a
worldwide distribution in temperate and tropical region of the Atlantic, Indian, Pacific
Oceans and all the Mediterranean Sea (COMPAGNO, 1984).
Along the Tunisian coasts, C. plumbeus is captured through the year mainly in
summer particularly along the southern-east coast (gulf of Gabès) where it finds the
favorite condition to reproduce (SAIDI et al., 2005a).The sandbar shark is the most
commonly landed carcharhinids, especially at fishing sites in the gulf of Gabès (Fig. 5).
Figure 5. C. plumbeus capture sites (black stars).
Commercial landings of this species increased from 250 t in 2000 to about 400
t in 2004 (Fig. 6). Males and females are mature at 1600 and 1720 mm TL (SAIDI et
al., 2005a). Pregnant females were observed between March and July, and then at the
end of July, they disappeared from landing. These pregnant females were captured by
113
Production (T)
demersal gillnets at depths between 10 and 20 m from March to May, and at depths
lesser than 10 m from June to July, on sandy-muddy bottoms. These females were
caught by special gillnets “Kallabia”. Soon after, neonates exhibiting an unhealed
umbilical scar on the ventral surface and post-partum females were captured from July
to October. Neonates are captured at depths between 10 and 50 m, especially on sandy
bottoms. Juveniles are captured along the year. These observations suggested that the
gulf of Gabès is a nursery area for this shark (BRADAI et al., in press).
500
450
400
350
300
250
200
150
100
50
0
1995 1996 1997 1998 1999 2000 2001 2002 2003 2004
Figure 6. Sandbar shark catches in gulf of Gabès.
White shark, Carcharodon carcharias
The white shark C. carcharias has been repeatedly documented from the
Mediterranean sea since Antiquity (FERGUSSON, 2002). Since POSTEL (1958), 27
captures of C. carcharias were reported off the Tunisian coast from which there is one
neonates and tow pregnant females. Of the 27 records, 11 were reported from the gulf of
Gabès. In 1992, first pregnant female carrying two embryos was captured off Cape Bon
(Tunisia northeastern) (FERGUSSON, 2002). On 26 February 2004, a second pregnant
female was caught off the Tunisian coast, in the gulf of Gabès (southern Tunisia)
(SAIDI et al., 2005b). FERGUSSON (2002) noted that along the Sicilian Canal, coastal
records of immature specimens (< 250 cm TL) were primarily of Tunisian origin,
coming from longlines and gillnets fisheries operating in the southeast of the country
(gulf of Gabès). These observations suggest that the species find favorable
environmental conditions to develop and reproduce in the area. FERGUSSON (2002)
stated that 41 % of white shark records in Mediterranean Sea are reported from the
Sicilian Channel and its adjoining environs suggesting that this zone is a reproductive
and nursery area for this Shark.
Beside the White shark and the Sandbar shark, other species seem to have also
nursery in the gulf of Gabès.
114
The smouth-hound, Mustelus mustelus
M. mustelus is landed along the year as a targeted or as by-catch species
(Figure 4). Our investigation shows that the pregnant females were captured at depths
between 10 and 20 ms from February to April, on sandy-muddy bottoms. From the
earlier May to the end of June, neonates exhibiting an unhealed umbilical scar on the
ventral surface and post-partum females were captured. On July females with
encapsulated eggs are captured at depth about 50 m. Neonates are captured at depths
between 10 and 30 m, especially on sandy bottoms. Juveniles are captured along the
year. These observations suggested that smooth-hound shark find in the Gulf of Gabès
the condition to reproduce and develop which could be considered as a nursery area for
the species.
The blackchin guitarfish, Rhinobatos cemiculus
R. cemiculus is targeted mainly between April and August by gillnets (Figure
7). On June-July females with encapsulated eggs are captured at depth about 20 m.
Neonates are captured at depths between 10 and 20 m, especially on sandy bottoms.
Juveniles are captured along the year in bottom trawlers. The presence of all size classes
of the Blackchin guitarfish in the southern east region of Gabès gulf (Zarzis, Djerba)
suggested that this ray find in the area the condition to reproduce and develop which
could be considered as a nursery area for the species.
70
Production (T)
60
50
40
30
20
10
0
J
F
M
A
M
J
J
A
S
O
N
D
Figure 7. Monthly landings of Rhinobatos cemiculus in Southeast of gulf of Gabès
(Zarzis).
Conclusion
This review of literature data and the new observations show that Tunisian coasts and
mainly the gulf of Gabès are very important places for the elasmobranch fauna in the
Mediterranean ; many species found favorable conditions to reproduce and to develop.
Nevertheless, precise information and data on distribution, biologic and fishing
115
parameters should be needed to ovoid over-exploitation and determine particular areas
to be protected. On other hand national action plan should be elaborate to maintain
catch at level of sustainable yield and to reduce incidental mortality due to fishing in
the frame of the implementation of the action plan for the conservation of cartilaginous
fishes (Chondrichtyans) in the Mediterranean sea adopted by Tunisia.
References
ANONYMOUS., 2004. Annuaire des statistiques des pêches en Tunisie (année 2004).
Direction Générale de la Pêche et de l’Aquaculture, pp 114.
BAINO, R., SERENA, F., 2000. Abundance evaluation and geographical distribution of
some selachii in the Northern Tyrrhenian Southern and ligurian seas. Biol. Mar.
Medit. 7(1), 433-439.
BRADAI, M. N., QUIGNARD, J. P., BOUAIN, A., JARBOUI, O., OUANNESGHORBEL, A., BEN ABDALLAH, L., ZAQUALI, J., BEN SALEM, S., 2004.
Ichtyofaune autochtone et exotique des côtes tunisiennes: recensement et
biogéographie. Cybium 28(4), 315-328.
BRADAÏ, M. N., SAIDÏ, B., BOUAIN, A., GUELORGET, O., CAPAPE, C., (In press)
The gulf of Gabès (Southern Tunisia, entral Mediterranean): a nursery area for
sandbar shark, Carcharhinus plumbeus (Nardo, 1827) (Chondrichthyes:
Carcharhinidae). Annales. Ser. hist. nat.
BRADAÏ, M. N., SAIDÏ, B., GHORBEL, M., BOUAIN, A., GUÉLORGET, O.,
CAPAPÉ, C., 2002. Observations sur les requins du golfe de Gabès (Tunisie
méridionale, Méditerranée centrale). Mésogée 60, 61-77.
CAPAPE, C., 1975. Sélaciens nouveaux et rares le long des côtes tunisiennes.
Première observations biologiques. Archs. Inst. Pasteur Tunis 51(1-2), 107-128.
CAPAPE, C., 1987. Propos sur les Sélaciens des côtes tunisiennes. Bull.
Inst.Océanogr. Pêche, Salammbô 14, 15-32.
CAPAPE, C., HEMIDA, F., BENSACI, J., SAIDI, B., BRADAI, M. N., 2003. Records
of basking sharks, Cetorhinus maximus (Gunnerus, 1765) (Chondrichthyes:
Cetorhinidae) off the Maghrebin shore (southern Mediterranean) : a survey. Annales.
Ser. hist. nat. 13(1), 13-18.
CAPAPE,C., ZAOUALI, J., DESOUTTER, M., 1979. Note sur la présence en Tunisie
de Carcharhinus obscurus (Lesueur, 1818) (Pisces, Pleurotremata) avec clé de
détermination des Carcharhinidae des côtes tunisiennes. Bull. off. natn. Pêch,
Tunisie. 3(2), 171- 182.
CASTRO, J.I., 1993. The shark nursery of Bulls Bay, South Carolina, with a review of
the sharks nurseries of the south eastern coast of the United States. Env. Biol. Fish.
38, 37-48.
CHAKROUN, F., 1966. Capture d’animaux rares en Tunisie. bull. Inst. natn. scient.
tech. Océanogr. Pêche Salammbô 1(2), 75-79.
COMPAGNO, L.V.J., 1984. FAO species catalogue, vol. 4. Sharks of the World. An
Annotated and Illustrated Catalogue of Shark Species Known to Date, part 2.
Carcharhiniformes. FAO Fish. Syn., 125(2), pp 251-655.
116
COSTANTINI. M, AFFRONTE, M.Ü, 2003. Neonatal and juveniles sandbar sharks in
the northern Adriatic Sea. J. Fish. Biol. 62(3), 740-744.
FERGUSSON, K.I., 2002. Occurrence and biology of the Great white shark
Carcharodon carcharias in the Central Mediterranean Sea: A review. In: VACCHI,
M., LA MESA G., SERENA F. & B. SERET (Eds), Proc.4th Europ. Elasm. Assoc.
Meet., Livorno, (Italy). ICRAM, ARPAT & SFI 2000, pp 7-23.
MANCUSI, C., CLÒ, S., AFFRONTE, M., BRADAÏ, M. N., HEMIDA, F., SERENA
F., SOLDO, A., VACCHI, M., 2005. On the presence of basking shark (Cetorhinus
maximus) in the Mediterranean Sea. Cybium. 29(4): 399-405.
NAJAI, S., 1980. Note sur la présence de deux requins pélerins dans le golfe de Tunis.
Bull. Inst. nat. Scient. Tech. Océanogr. Pêche, Salammbô. 7, 151-152.
POSTEL, E., 1958. Sur la présence de Carcharodon carcharias (L., 1758) dans les
eaux tunisiennes. Bull. Mus. Nat. Hist. Nat., Paris, 2ème sér. 30, n°4, 1 fig., pp 42-344.
QUIGNARD, J.P., CAPAPE, C., 1971. Liste commentée des Sélaciens de Tunisie. Bull.
Inst. Natn. scient. tech. Océanogr. Pêche, Salammbô. 2(2), 131-141.
QUIGNARD, J.P., CAPAPE, C., 1972. Complément à la liste commentée des Sélaciens
de Tunisie. Bull. Inst. Natn. scient. tech. Océanogr. Pêche, Salammbô. 2(3), 445-447.
SAIDÏ, B., BRADAÏ, M.N., BOUAIN, A., GUELORGET, O., CAPAPE, C., 2005a.
Reproductive biology of tea sandbar shark, Carcharhinus plumbeus (Chondrichthyes:
Carcharhinidae) from Gulf tea Gabès of (Southern Tunisia, Central Mediterranean).
Acta. Adriat. 46(1), 47-62.
SAIDÏ, B., BRADAÏ, M.N., BOUAIN, A., GUELORGET, O., CAPAPE, C., 2005b.
Capture of a pregnant female white shark, Carcharodon carcharias (Lamnidae) in the
gulf of Gabès (southern Tunisia, central Mediterranean) with comments on oophagy
in sharks. Cybium. 29(3), 303-307.
SERENA, F., 2005. Field identification guide to sharks and rays of Mediterranean and
Black Sea. FAO Species Identification Guide for Fisheries Purpose. Rome, pp 95. 11
colour plates + egg cases.
SPRINGER, S., 1967. Social organization of shark populations. In: GILBERT, R. F.
MATHESON and D.P. RALL (Eds.) Shark, Skates, and Rays, John Hopkins Press,
Baltimore, pp 149-174.
117
Proc. of the Int. Workshop on Med. Cartilaginous Fish with Emphasis on South.- East. Med., 14-16 Oct. 06, Istanbul-Turkey
THE MEDLEM DATABASE APPLICATION: A TOOL FOR STORING
AND SHARING THE LARGE SHARK’S DATA COLLECTED IN THE
MEDITERRANEAN COUNTRIES
Fabrizio SERENA1, Monica BARONE1, Celilia MANCUSI1,
Glauco MAGNELLI1 and Marino VACCHI2
1
Agenzia Regionale per la Protezione Ambientale della Toscana
Via Marradi 114 57100 Livorno, Italy. E-mail: f.serena@arpat.toscana.it
2
ICRAM c/o MNA-Università di Genova
Abstract
The MedLem Database Application is a user-friendly computerized system designed to
facilitate sharing of large cartilaginous fish data between participants in the MedLem
programme. Main objectives of the MedLem Database Application are an
implementation of data collection, the standardization of the data entry procedures and a
free access for the participants to the site www.arpat.toscana.it/xxx/medlem.htlm.
Furthermore, the MedLem Database provides an updated source of information on large
cartilaginous fishes for national and international organizations involved in the
management and the conservation of these marine vertebrates in the Mediterranean Sea.
The application allows the data entry of catch, sighting, stranding or bibliographic
reference, or a search for species, country and gear. An example of the practical use of
these data stored in the MedLem database is presented.
Key words: Large elasmobranchs, Mediterranean Sea, information system, open
source software.
Introduction
The MedLem Database Application is a computerized system, based on Open Source
software, designed as a simple tool to store and share the available data collected in the
framework of the MedLem programme. As one of the major intention of the MedLem
programme were to collect and share data following a common protocol, the idea
was to design an user-friendly application that would allow all participants to insert
new data and making search easily through a free accessible site
(www.arpat.toscana.it/xxxx/medlem.htlm). In addition a new data sheet, which fields
are standardized with the MEDLEM Database Application, is presented (Fig. 1).
In all the seas of the world, the cartilaginous fish species are exploited for their
fins, skin, jaws or meat. Sometimes they are directly targeted in commercial and
recreational fisheries while in other cases they are caught incidentally as by-catch. In
many areas of the world a decline in cartilaginous fish species landings has been
observed while fishing effort has generally increased. This especially applies to the
118
fisheries that target shark fins. Moreover, most countries report statistics related to
sharks without making a distinction between species or, in worse still, they are not
recorded at all. As a result, it is impossible to recognize the species in multi-specific
fishery. Due to an inadequate collection of statistics on landings, it is difficult to
estimate and monitor fishing mortality (SERENA, 2005).
Background information on MedLem programme
MedLem is a monitoring programme on the captures and sightings of the large
cartilaginous fishes occurring in the Mediterranean Sea. This programme directly links
up with the FAO IPOA-SHARKS and it has been submitted to the discussion of the
SAC Sub-Committee on Marine Environment and Ecosystems (SCMEE) of the GFCM
(Barcelona, 6-9 May 2002) as “subproject Basking shark” (FAO, 2002a; 2002b).
During the meeting of the SCMEE held in Spain (Malaga, 10-12 May 2004) a
common protocol to collect field data were proposed and many Mediterranean countries
showed a willingness to cooperate on this initiative and to conform in the collection of
data (Table 1) (FAO, 2004). In The seventh session of the General Fisheries
Commission for the Mediterranean (GFCM) Scientific Advisory Committee (SAC),
held in Italy (Rome, 19-22 October 2004), SCMEE reiterated the importance of a wider
use of the MedLem protocols and information system already adopted by a number of
regional bodies to favour timely exchange of information on Large Elasmobranchs
(FAO, 2005). Up to now, an updating of information on incidental catches of protected
species and on by catch of large migratory sharks in the commercial fisheries is still
done.
•
•
Among the principal aims of the programme are:
Contribute to the knowledge and conservation of the sharks following a
common protocol to collect data about the specimens sighted, stranded or
accidentally captured in the Mediterranean Basin.
The collection of scientific papers related to elasmobranches in the
Mediterranean area.
Main objectives of the MedLem Database Application
The creation of the MedLem application allowed for
•
•
•
•
Implementation of data collection;
Standardization of the data entry procedures;
Effective data sharing among the participating countries.
Free access for the participants to the site
www.arpat.toscana.it/xxx/medlem.htlm
Materials and Methods
Cartilaginous fish data
In relation to this project “large cartilaginous fish” is defined as an
elasmobranch of more than 100 cm Total Length or a batoid fish with a Disc Width
119
more than 100 cm or Total Length more than 150 cm. The size of the monitored
cartilaginous fishes is established on the basis of the maximum size reached from the
different species. For this reason the species to be considered in the project belong to the
families reported in Table 2.
However, in the list of the species recorded in the frame of the MedLem
project are present also some “small” specimens, not considered “large cartilaginous
fishes”, like Galeorhinus galeus, Mustelus punctulatus, Mustelus sp.. This is due to the
fact that these species are very rare in some Mediterranean areas, in Italian seas for
example, and we thought of interest to report their accidental caught. Some other
species can be rather common in the southern part of the Mediterranean basin, present
also in the commercial landings (e.g. Rhinobatos cemiculus and R. rhinobatos) and
never registered or very rare in other parts of the region.
Application characteristics
The MedLem Database Application use Open Source software. The advantages
of Open Source model are:
•
•
•
•
•
Simplified license management: obtain the software once and install it as
many times and in as many locations as you need.
Lower software costs: Open source solutions generally require no licensing
fees.
Lower hardware costs: in general, Linux and open source solutions are
elegantly compact and portable, and the result is you can get by with less
expensive or older hardware.
Ample support: support is available for open source, often superior to
proprietary solutions. First, open source support is freely available and
accessible through the online community via the Internet. And second, many
tech companies are now supporting open source with free online and multiple
levels of paid support.
Quality software: evidence and research indicate that open source software is
good stuff. The peer review process and community standards, plus the fact
that source code is out there for the world to see, tend to drive excellence in
design and efficiency in coding.
Open source software used by MedLem Database Application (Fig. 2):
•
•
Perl: Perl is a stable, cross platform programming language created by Larry
Wall. It is used for mission critical projects in the public and private sectors.
Perl is Open Source software, licensed under its Artistic License, or the GNU
General Public License (GPL).
Apache: The Apache HTTP Server Project is an effort to develop and maintain
an opensource HTTP server for modern operating systems including UNIX and
Windows NT. The goal of this project is to provide a secure, efficient and
120
•
•
•
•
extensible server that provides HTTP services in sync with the current HTTP
standards.
Linux: Linux is a free Unixtype operating system originally created by Linus
Torvalds with the assistance of developers around the world. Developed under
the GNU General Public License, the source code for Linux is freely available
to everyone.
MySQL: The MySQL database has become the world's most popular open
source database because of its consistent fast performance, high reliability and
ease of use.
CGI: The Common Gateway Interface (CGI) is a standard for interfacing
external applications with information servers, such as HTTP or Web servers.
DBI: The DBI is the standard database interface module for Perl. It defines a
set of methods, variables and conventions that provide a consistent database
interface independent of the actual database being used.
Database organization
In Figure 3 a flowchart to follow during the start up of the application is given.
As to access to MedLem application username and password are needed, each user will
be required to compile a registration form; then username, password and instructions
will be sent by e-mail only to users belonging to institutions or organizations involved
in the project. Once users access to the application, they can choose both to entry data
on catch, sighting, stranding or bibliographic reference inherent large cartilaginous fish
(Fig. 4), or to do a search for species, country and gear (Fig. 5). As the data entry
procedure is based on the previous compilation of the data collection field sheet, users
who have properly compiled the data sheet will be advantageous.
The data are stored into six main tables: DATA, BIOLOGY, SPECIES,
BIBLIOGRAPHY, GEAR, PERSON IN CHARGE (Fig. 6). Users are not allowed to
see or manage these tables but the knowledge of the fields required by the system is
essential to understand the application performance properly.
Results
Thanks to the collaboration with several research institutes, military authorities and with
professional and recreational fishermen, MedLem programme allowed the acquisition of
valuable information on catch, sighting and stranding of large cartilaginous fish, starting
from 1795. As the most part of event recorded into the MedLem database concern
Cetorhinus maximus (Gunnerus, 1765) (Table 3), an example of the practical use of
these data is presented by MANCUSI et al (2005) in figures 7, 8 and 9 presence and
distribution of basking shark in the Mediterranean, the major fishing gears responsible
for the by-catch of basking sharks and the frequency of accidental catches are showed.
References
C. MANCUSI, CLÒ, S., AFFRONTE, M., BRADAÏ, M. N., HEMIDA, F., SERENA,
F., SOLDO, A., VACCHI, M., 2005. On the presence of basking shark (Cetorhinus
121
maximus) in the Mediterranean Sea. Sur la présence du requin-pèlerin (Cetorhinus
maximus) en Méditerranée. Cybium 29 (4), 399-405
FAO, 2002a. GFCM:SAC5/2002/Inf.5 - Report of the Third Session of the SubCommittee on Marine Environment and Ecosystems, Barcelona, Spain, 6-9 May 2002
(ftp://ftp.fao.org/FI/DOCUMENT/gfcm/sac_scmee/2002/SCMEE_May2002.pdf).
FAO, 2002b. FAO General Fisheries Commission for the Mediterranean/Commission
générale des pêches pour la Méditerranée. Report of the fifth session of the Scientific
Advisory Committee 2002. Rome, 1-4 July 2002. Rapport de la cinquième session du
Comité scientifique consultatif. Rome, 1-4 juillet 2002 FAO Fisheries Report/FAO
Rapport sur les pêches. No. 684. Rome, FAO, 2002, pp 100.
FAO, 2004. GFCM:SAC7/2004/Mad.1 - Report of the Fifth Session of the SubCommittee on Marine Environment and Ecosystems, Malaga, Spain, 10-12 May 2004
(ftp://ftp.fao.org/fi/document/gfcm/sac_scmee/2004/report_SCMEE_2004.pdf).
FAO, 2005. FAO/General Fisheries Commission for the Mediterranean/Commission
générale des pêches pour la Méditerranée 2005. Report of the seventh session of the
Scientific Advisory Committee. Rome, 19-22 October 2004. Rapport de la septième
session du Comité scientifique consultatif. Rome, 19-22 octobre 2004. FAO
Fisheries Report/FAO Rapport sur les pêches. No. 763. Rome, FAO, 2005, pp 83.
SERENA F., 2005. Field identification guide to the sharks and rays of the
Mediterranean and Black Sea. FAO Species identification Guide for Fishery
Purposes. Rome, FAO. 97, p 11, colour plates+egg cases.
122
Table 1. List of the institutions or organizations and their referent involved in the
project
ARPAT, Livorno (Italy)
ICRAM, Roma (Italy)
IEO, Malaga (Spain)
IMEDEA, Spain
INSTM, Tunisia
N.AG.RE.F, Greece
Institute of Oceanography and
USTHB, Algeria
National & Kapodistrian University of
Marine Sciences laboratory, Fac. of
Malta Centre for Fisheries Science
IUCN-SSG
European Elasmobranchs Association
Societa Italiana Biologia Marina (Italy)
Fabrizio Serena
Marino Vacchi
Luis Jil de Sola
Gabriel Morey
Mohamed Nejmeddline Bradai
Argiris Kallianotis
Alen Soldo
Farid Hemida
Persefoni Megalofonou
Adib Ali Saad
Matthew Camilleri
Table 2. List of the families to be considered in the MedLem project.
HEXANCHIDAE
ECHINORHINIDAE
SQUATINIDAE
PRISTIDAE
RHINOBATIDAE
RAIJDAE
DASYATIDAE
GYMNURIDAE
MYLIOBATIDAE
RHINOPTERIDAE
MOBULIDAE
ODONTASPIDIDAE
ALOPIIDAE
CETORHINIDAE
LAMNIDAE
CARCHARHINIDAE
SPHYRNIDAE
123
Table 3. Number of species present in the MedLem database up to now
Scientific name
Alopias vulpinus (Bonnaterre, 1788)
Carcharhinus brachyurus (Günther, 1870)
Carcharhinus plumbeus (Nardo, 1827)
Carcharodon carcharias (Linnaeus, 1758)
Cetorhinus maximus (Gunnerus, 1765)
Dalatias licha (Bonnaterre, 1788)
Galeocerdo cuvier (Péron and Lesueur, in Lesueur 1822)
Galeorhinus galeus (Linnaeus, 1758)
Hexanchus griseus (Bonnaterre, 1788)
Isurus oxyrinchus Rafinesque, 1810
Lamna nasus (Bonnaterre, 1788)
Mobula mobular (Bonnaterre, 1788)
Mustelus punctulatus (Risso, 1826)
Mustelus sp.
Oxinutus centrina (Linnaeus, 1758)
Prionace glauca (Linnaeus, 1758)
Pteromylaeus bovinus (Geoffroy St-Hilaire, 1817)
Sphyrna zygaena (Linnaeus, 1758)
Taeniura grabata (Geoffroy St-Hilaire, 1817)
Total
124
n°
26
1
1
9
610
1
1
2
18
2
4
19
6
12
3
7
1
3
1
743
Fig. 1 Data collection field sheet of MedLem project (See Annex II of this volume for details).
Figure 2. Architecture of the MedLem application
125
Figure 3. Flowchart of MedLem database application
Figure 4. One of the pages of data entry in MedLem database application.
Figure 5. Page of search in MedLem database application.
126
∞
BIOLOGY
cod_bio
Sex
Teeth shape
Teeth photo
Stomach content
Embryo in uterus
Intestine contents
Gonads
Vertebrae
Muscle
Liver
Underskin fat
Spermatophores
Parasite
Utera
Morphometry
....
SPECIES
cod_species
Scientific name
3A_CODE
English_name
French_name
Spanish_name
Arabic_name
Italian_name
1
1
1
∞
∞
ID
cod_ref
DATA
ID
DAY
Date (dd/mm/yyyy)
Season
Time
Country
GSA
Locality
Latitude (DecDeg)
Longitude
Original Lat/Long (Y/N)
Distance from coast (NM)
Direction
Depth (m)
Type of report
Number
Total lenght (cm)
Weight (kg)
Other sources
Photo
Notes
cod_bio
cod_gear
cod_species
cod_person
1
BIBLIOGRAPHY
cod_ref
Author
Year
Title
Publication
1
GEAR
cod_gear
Gear (English_name)
Gear (French_name)
Gear (Spanish_name)
Gear (Italian_name)
Gear (Arabic_name)
1
PERSON IN CHARGE
cod_person
Last name
Name
Institution
Address
Telephone
Fax
Mobile phone
1
∞
∞
Figure 6. Table and relationship of MedLem database application.
Figure 7. Geographical allocation of observations and captures of Cetorhinus maximus in the Mediterranean Sea
(MANCUSI et al., 2005).
Figure 8. Incidental catches of C. maximus split by
fishing gear (MANCUSI et al., 2005).
Figure 9. Frequency of incidental catches of C. maximus
by year in the Mediterranean. (MANCUSI et al., 2005).
127
Proc. of the Int. Workshop on Med. Cartilaginous Fish with Emphasis on South.- East. Med., 14-16 Oct. 06, Istanbul-Turkey
STATUS OF THE SHARKS IN THE ADRIATIC
Alen SOLDO
Institute of Oceanography and Fisheries, Split, Croatia.
Abstract
Several authors have reported lists of shark species in the Adriatic. Recent list
considered as unreliable some previously reported shark species for the Adriatic and
considered the total of 28 species as confirmed. Most of the shark species are not target
species in the Adriatic area but they were caught mainly as bycatch by various fishing
gears. Shark targeted fisheries are only for dogfish and hound sharks, which are
performed by gillnets designated exclusively for such fishery. This paper reports data on
currently known status of shark species in the Adriatic and gives suggestions for
ensuring conservation of shark populations and biodiversity of marine ecosystem of the
Adriatic.
Key words: Adriatic Sea, sharks, conservation.
Introduction
Several authors have reported lists of cartilaginous fishes in the Adriatic (ŠOLJAN,
1948; MILIŠIĆ, 1994; JARDAS, 1996). Usually they were reporting around 54
different cartilaginous species, within this number 29 species were sharks, 24 batoids
(skates and rays) and 1 species of chimaeroids. Some of those species were constantly
present in the Adriatic, while some were reported only occasionally. MILIŠIĆ (1994)
reported 31 species of sharks, containing two additional species: oceanic whitetip shark,
Carcharhinus longimanus, and little gulper shark, Centrophorus uyato, but those data
are very questionable and uncertain.
BELLO (1999) reported only 28 species with an exception of smalleye
hammerhead, Sphyrna tudes (Valenciennes, 1822), whose occurrence in the Adriatic
Sea, according to him, still needs to be confirmed. The same author also wanted to find
the origin of the data regarding S. tudes, but he was unable to trace it. Sphyrna tudes is
one of the most questionable shark species not only in the Adriatic, but in the whole
Mediterranean as well. COMPAGNO (1984) has not considered the Mediterranean as
the area of its distribution, QUERO (1984) reported several records in the
Mediterranean (one in western Greek waters), while FISCHER et al. (1987), within the
other Mediterranean records reported one record from the Southern Adriatic. Only 2
records, both from 19th century, have been reported in the Eastern Adriatic and they are
based on data from KOLOMBATOVIĆ (1894) who had determined and reported
several young specimens of smalleye hammerhead. Consequently, all succeeding
lists of the Adriatic sharks, where S. tudes was listed, were based on that
report (KOSIĆ, 1903; ŠOLJAN, 1948; MILIŠIĆ, 1994; JARDAS, 1996).
128
Based on findings of origin of the data on S. tudes, recent book on sharks (LIPEJ et al.,
2004) has not included this species in the list of Adriatic sharks, as according to the
authors key for the determination of this species in 19th century was not certain.
Therefore, this report was considered as unreliable and only 28 shark species have been
considered as confirmed for the Adriatic area (Table 1).
Table 1. List of shark species reported in the Adriatic with English and Croatian names.
Order
Families
HEXANCHIFORMES
HEXANCHIDAE
SQUALIFORMES
ECHINORHINIDAE
SQUALIDAE
CENTROPHORIDAE
ETMOPTERIDAE
OXYNOTIDAE
DALATIIDAE
SQUATINIFORMES
SQUATINIDAE
LAMNIFORMES
ODONTASPIDIDAE
ALOPIIDAE
CETORHINIDAE
LAMNIDAE
129
Species
Heptranchias perlo (Bonnaterre, 1788).
Sharpnose sevengill shark. Volonja
sedmoškrgaš.
Hexanchus griseus (Bonnaterre, 1788).
Bluntnose sixgill shark. Glavonja
šestoškrgaš.
Echinorhinus brucus (Bonnaterre, 1788).
Bramble shark. Pas zvjezdaš.
Squalus acanthias Linnaeus, 1758. Piked
dogfish. Kostelj.
Squalus blainvillei (Risso, 1826).
Longnose spurdog. Kostelj dugonosi.
Centrophorus granulosus (Bloch &
Schneider, 1801). Kostelj dubinac.
Etmopterus spinax (Linnaeus, 1758).
Velvet belly. Kostelj crnac.
Oxynotus centrina (Linnaeus, 1758).
Angular roughshark. Prasac.
Dalatias licha (Bonnaterre, 1788). Kitefin
shark. Drkovna.
Squatina oculata Bonaparte, 1840.
Smoothback angelshark. Sklat žutan.
Squatina squatina (Linnaeus, 1758).
Angelshark. Sklat sivac.
Carcharias taurus Rafinesque, 1810.
Sand tiger shark. Psina zmijozuba
ružičasta.
Odontaspis ferox (Risso, 1810).
Smalltooth sand tiger. Psina zmijozuba.
Alopias vulpinus (Bonnaterre, 1788).
Thresher shark. Lisica.
Cetorhinus maximus (Gunnerus, 1765).
Basking shark. Gorostasna psina.
Carcharodon carcharias (Linnaeus,
1758). Great white shark. Velika bijela
psina.
Isurus oxyrinchus Rafinesque, 1810.
Shortfin mako. Psina dugonosa.
Table 1 (Cont.)
CARCHARHINIFORMES
SCYLIORHINIDAE
TRIAKIDAE
CARCHARHINIDAE
SPHYRNIDAE
Lamna nasus (Bonnaterre, 1788).
Porbeagle shark. Atlantska psina.
Galeus melastomus Rafinesque, 1810.
Blackmouth catshark. Mačka crnousta.
Scyliorhinus canicula (Linnaeus, 1758).
Smallspotted catshark. Mačka bljedica.
Scyliorhinus stellaris (Linnaeus, 1758).
Nursehound. Mačka mrkulja.
Galeorhinus galeus (Linnaeus, 1758).
Tope shark. Butor.
Mustelus asterias Cloquet, 1821. Starry
smoothhound. Pas mekuš.
Mustelus mustelus (Linnaeus, 1758).
Smoothhound. Pas čukov.
Mustelus punctulatus Risso, 1826.
Blackspot smoothhound. Pas mekuš
piknjavac.
Carcharhinus plumbeus (Nardo, 1827).
Sandbar shark. Pas tupan.
Prionace glauca (Linnaeus, 1758). Blue
shark. Modrulj.
Sphyrna zygaena (Linnaeus, 1758).
Smooth hammerhead. Mlat.
Most of the shark species are not target species in the Adriatic Sea but they are
caught mainly as bycatch by longlines, driftnets and other fishing gear used in tuna,
small pelagic fish and swordfish fisheries. Smaller shark species are also often bycatch
of trawls. In certain areas during some seasons dogfish and hound sharks are targeted
with gillnets, but only few fishermen are involved in this fishery.
Current Croatian legislation does not have any regulations for shark
conservation and management, so shark catches and bycatch are not reported in the
eastern Adriatic.
Materials and Methods
Data presented in this paper were collected from scientific and popular literature and by
unpublished data from personal research. All common names of sharks used in this
paper follow FAO nomenclature (COMPAGNO, 1984).
Results and Discussion
Due to lack of any fishery statistics, members of Institute of Oceanography and
Fisheries - Split started and conducted monitoring of large sharks in 1999 on a voluntary
basis and collaboration with fisherman, journalists, marine police, harbor offices,
private citizens, etc.
130
This monitoring allowed to collect data on several large shark species. From
1868 to 2000, a total of 62 records on occurrence of the great white shark, C. carcharias
in the Eastern Adriatic Sea have been collected. The records showed a distribution of
the great white throughout whole eastern coast of Adriatic, mainly in the northern
Adriatic, especially in the area of Kvarner Bay and adjacent islands.
SOLDO and JARDAS (2002) related the presence of the great white shark in
coastal waters of the eastern Adriatic with high abundance of tuna in these waters
during 19th century and first half of 20th century, which were their major prey. The start
of intensive tuna fishing in open waters of the Adriatic, especially during the 70’s,
caused the disappearance of tuna in coastal waters of the eastern Adriatic, and as a
consequence the disappearing of the great white shark records in these waters. Same
authors also presumed that any future records of the great white shark in the Eastern
Adriatic would be, probably, only accidental entering from the Mediterranean. New
record, and first since 1974, confirmed such speculation on 24-25. June 2003, a female
was caught in tuna purse seine 15 Nm southwest off Jabuka island (SOLDO and
DULČIĆ, 2005).
Data on shortfin mako (I. oxyrinchus) have showed even more severe. FourtyThree records out of total 48, were reported during 19th century and since 1972 there
were no more records of this species in the Eastern Adriatic. However, it is possible that
shortfin mako still occurs in open waters of the Adriatic where it is misidentified by
fisherman as blue shark (P. glauca), or some other shark species. Unconfirmed data
pointing that this species could be bycatch of pelagic longlines and driftnets used in the
southern Adriatic.
Porbeagle shark (L. nasus) has been reported 11 times in the eastern Adriatic,
most in the 20th century. All records were reported in open waters of the Adriatic what
is in accordance with its description as an offshore and epipelagic shark. As in the case
of shortfin mako (misidentification and inadequate fishing gear), it is possible that
occurrence of the porbeagle is even higher than reported (SOLDO and JARDAS, 2002).
Recent records (1999, 2002, 2005) prove they are reported accidentally as bycatch of
big game fishing, activity that rapidly grow up in the eastern Adriatic area in recent
years.
The basking sharks (Cetorhinus maximus) and hammerhead sharks (Sphyrna
spp). are rather rare in this area, although the evidence (by comparing records in the 19th
century with the 20th century) suggests that they have been more abundant in the past.
However, in the case of the basking sharks there has been a notable increase in records
reported in the eastern Adriatic since 2000, especially during 2001 (ZUFFA et al.,
2001). This unusual phenomenon is related to changes in zooplankton abundance,
mainly of copepod species, with particular emphasis on Calanus helgolandicus, on
which basking shark prey.
Particular problems are regarding other large species of sharks, whose
populations with smaller or higher number of specimens exist in the eastern Adriatic,
but these species are often misidentified, so their records are not reported.
The bluntnose sixgill shark (H. griseus) and sharpnose sevengill shark (H.
perlo) are often caught as bycatch in trawls and by deep bottom longlines, but their
131
current status in the Adriatic is unknown. Similar case is of the sandtiger shark (C.
taurus) and the smalltooth sand tiger (O. ferox), that were previously reported often, but
in recent years there are no records of them. The thresher shark (A. vulpinus), was
common in the eastern Adriatic and was caught, as bycatch, in purse seines and by tuna
longlines, like the blue shark (P. glauca), the most common species of large sharks in
the Adriatic. Big game fishing regularly targeted these two species, so fishermen
involved in that activity have observed rapid decline of those species in their catches
during last few years.
Recently, the Adriatic was supposed to be nursery and spawning areas for
many large shark species. For C. plumbeus (CONSTANTINI and AFFRONTE, 2003)
and A.vulpinus (NOTARBARTOLO DI SCIARA and BIANCHI, 1998) in the northern
part, for P. glauca and O. centrina in the middle part, and for L. nasus in the southern
Adriatic (SOLDO, unpublished data) (Fig. 1).
Figure 1. Possible nursery areas in the Adriatic for Carcharhinus plumbeus (CP),
Alopias vulpinus (AV), Prionace glauca (PG), Oxynotus centrina (OC), and
Lamna nasus (LN).
132
It is of great importance to identify critical habitats, namely mating areas,
spawning and nursery grounds of all shark species in the Adriatic. Furthermore, it is
necessary to develop management programmes that would ensure acurate fisheries
statistics of catches and landings by species. Although there are no proper fishery
statistics, comparison of catches of chondrichthyan fishes caught by trawls in 1948-49
during research expedition “HVAR” with the data from “MEDITS” program in 1997-98
shows considerable decline in abundance of 26 species of chondrichthyans, as well as
major reductions of their distribution. The Hypotremata group showed the greatest
decline, as their biomass percentage decline from 20 % during HVAR research to 7 %
in MEDITS (JUKIĆ-PELADIĆ et al., 2001). Hence, the thornback ray, Raja clavata in
1948-49 had high abundance and widespread distribution throughout the Adriatic Sea,
while was restricted to a small area with low abundance in 1997-98 (SOLDO, 2002).
Therefore, more thorough investigations are necessary to lead to the
implementation of a management plan for the Adriatic Sea, to prevent overexploitation
and preserve the biodiversity in this region. Shark management programmes in the
Mediterranean, followed by local ones (Adriatic) should respect the principles of
sustainability, precautionary principle and conservation measures as defined in the FAO
Code of Conduct for Responsible Fisheries and in the International Plan of Action for
the Conservation and Management of Sharks.
Such approach is urgently needed, as any delays can have severe consequences
on conservation of shark populations and biodiversity of marine ecosystem of the
Adriatic, as well as in the Mediterranean Sea.
References
BELLO, G., 1999. The chondrichthyans of the Adriatic Sea. Acta Adriatica 40(1), 6576.
COMPAGNO, L. J. V., 1984. Sharks of the world, FAO Species catalogue, Vol. 4, Part
1, 2, pp 655.
COSTANTINI, M. & AFFRONTE, M., 2003. Neonatal and juvenile sandbar sharks in
the northern Adriatic Sea. J. Fish. Biol. 62, 740-743.
FISCHER, W., SCHNEIDER, M., BAUCHOT, M. L., 1987. Vertebres, Mediterranee et
Mer Noire, Vol. II, FAO ECEE, Rome, pp 763-1529.
JARDAS, I., 1996. Jadranska ihtiofauna, Školska knjiga, Zagreb, pp 536.
JUKIĆ-PELADIĆ, S., VRGOČ, N., KRSTULOVIĆ-ŠIFNER, S., PICCINETTI, C.,
PICCINETTI-MANFRIN, G., MARANO, G., UNGARO, N., 2001. Long-term
changes in demersal resources of the Adriatic Sea: comparison between trawl surveys
carried out in 1948 and 1998. Fisheries research 53, 95-104.
KOLOMBATOVIĆ, J., 1894. O navodima vrsti meči i kralježnjaka iz Jadranskog mora,
Izvješće Vel. Realke, Split, 1-58.
KOSIĆ, B., 1903. Ribe dubrovačke, Knjiga 155, JAZU, Zagreb, pp 48.
LIPEJ, L., De MADDALENA, A., SOLDO, A., 2004. Sharks of the Adriatic Sea.
Knjižnica Annales Majora, Koper, pp 254.
MILIŠIĆ, N., 1994. Sva riba Jadranskog mora, Niva, Split, pp 463.
133
NOTARBARTOLO DI SCIARA, G., BIANCHI, I., 1998. Guida degli squali e delle
razze del Mediterraneo. F. Muzzio Ed. Padova, pp 388.
QUERO, J. C. 1984. Sphyrnidae, In: WHITEHEAD P. J. P., BAUCHOT M.-L.,
HUREAU J.-C., NIELSEN J., TORTONESE E. (Eds.), Fishes of the North-eastern
Atlantic and the Mediterranean, UNESCO, pp 122-127.
SOLDO, A., 2002. Status of cartilaginous fish in the Eastern Adriatic (Croatia). Report
of the meeting of experts for the elaboration of an action plan for the conservation of
Mediterranean species of cartilaginous fish. UNEP(DEC)/MED/WG. 211, 4, 4-9
SOLDO, A., DULČIĆ, J., 2005. New record of a great white shark, Carcharodon
carcharias (Lamnidae) from the eastern Adriatic Sea. Cybium 29(41), 89-90.
SOLDO, A., JARDAS, I., 2002. Large sharks in the Eastern Adriatic. In: VACCHI, M.,
LA MESA, G., SERENA, F., SERET, B. (Eds), Proc. 4th. Europ. Elasm. Assoc.
Meet., Livorno, (Italy), ICRAM, ARPAT & SFI 2000, 141-155.
ŠOLJAN, T., 1948. Ribe Jadrana, Fauna i flora Jadrana, 1, IOR Split, pp 437.
ZUFFA, M., SOLDO, A., STORAI, T., 2001. Preliminary observations on abnormal
abundance of Cetorhinus maximus (Gunnerus, 1765) in the Central and Northern
Adriatic Sea. Annales, Ser. Hist. Nat. 11, 2 (25), 185-192.
134
Proc. of the Int. Workshop on Med. Cartilaginous Fish with Emphasis on South.- East. Med., 14-16 Oct. 06, Istanbul-Turkey
USE OF SCIENTIFIC CAMPAIGNS (TRAWL SURVEYS) FOR THE
KNOWLEDGE OF THE SENSITIVE HABITATS.
A REVIEW OF THE MEDITS, GRUND AND APHIA DATA WITH
SPECIAL ATTENTION TO THE ITALIAN SEAS
Fabrizio SERENA1 and Giulio RELINI2
1
ARPAT Via Marradi 114 - 57100 Livorno, Italy. E-mail: f.serena@arpat.toscana.it
2
DIP.TE.RIS. Università di Genova Viale Benedetto XV, 3 -16132 Genova, Italy
Abstract
National and international trawl surveys have been carried on in the Mediterranean
since 1985. The analysis of abundance indexes and size structure of the chondrichthyan
populations is important to identify and delimitate the nursery areas and the juveniles
concentrations. Some examples for elasmobrachs and rays are reported for the southern
Ligurian and North Tyrrhenian Sea.
Keywords: Trawl survey, nursery area, Mediterranean Sea.
Introduction
In the Mediterranean and Black Sea about 84 chondrichthyan species of potential
interest for fishery have been identified (SERENA, 2005). These species show different
distribution patterns in the basin. In the Greek waters, 62 species of elasmobranchs have
been listed within a total of 447 fish species (PAPAKONSTANTINOU, 1988). The
situation is quite similar in the Catalan Sea with 62 elasmobranch species for a total of
454 fish species (LLORIS et al., 1984; STEFANESCU et al. 1992). In the Italian seas
490 fish species were recorded and among these 74 are represented by cartilaginous
fishes (1 Chimaeriformes, 43 Squaliformes, 30 Rajiformes) (AMORI et al., 1993).
Demersal scientific campaigns in the Mediterranean Sea have been carried out at
national and international level as MEDITS and GRUND projects (BERTRAND et al.,
1997; RELINI, 1998). These surveys produced a lot of information on a large number of
species occurring on the shelves and on the upper slopes and represent an opportunity to
improve the knowledges on a great number of species. The list of cartilaginous fishes
caught during national trawl surveys (1985-1998) within the GRUND project in all the
Italian seas, reports 44 demersal species (1 Rabbit fish, 17 sharks, 26 rays) (RELINI et
al., 2000). Different studies on the distribution of fishes, including elasmobranchs, in
the Mediterranean basin are also available (GIL DE SOLA SIMARRO, 1994). Also
some local or regional projects represent very important tools to collect information
about the distribution, biology and ecology of this group of fishes (ABELLA et al.,
1997; Catalano et al., 2003). In some cases, trends in abundance and diversity of these
species
135
have been described (ALDEBERT, 1997; FERRETTI et al., 2005; SERENA et al.,
2005).
In the Mediterranean-Black Sea region the distribution of cartilaginous fishes
show two particular situations: in the Adriatic Sea, the abundance of chondrichthyan
species is scarce especially in the northern part perhaps due to the hydrological
characteristics of this area that may limit biodiversity; infact the deeper currents do not
reach this area. A total of 52 species of cartilaginous fish have been recorded and only
10 of them are widely distributed. Some bathyal species of the group inhabit exclusively
the central and southern parts of this sea (JARDAS, 1984; JUKIC-PELADIC et al.,
2001). The number of cartilaginous fish species is very low in the Black Sea too: only
12 chondrichthyans species are assumed to occur in this basin (TORTONESE, 1956;
BAUCHOT, 1987; ROUX, 1984; McEACHRAN and CAPAPÉ, In: Whitehead et al.,
1984; FREDJ and MAURIN, 1987). BİLECENOGLU et al. (2002) consider only 8
elasmobranchs along the Turkey coast of the Black Sea.
The goal of this paper is to provide some general indications on the diversity
and distribution of chondrichthyans in the Mediterranean using data collected with the
trawl surveys and to underline the importance of these projects in order to indicate the
areas where juveniles specimens are concentrated. In some cases, the identification of
breading and feeding areas are important as well.
Materials and Methods
The data used for this review were issued from standardized bottom trawl surveys
carried out in the Mediterranean especially in the Italian seas from 1985 to 2004. We
consider here the MEDITS and GRUND trawl surveys and others demersal scientific
campaigns as APHIA for Aphia minuta stock assessment (BERTRAND et al., 1997;
RELINI et al., 1998; ABELLA et al., 1997) and RAIA TAG project, a tag and release
survey on juveniles of Raja asterias (CATALANO et al., 2003) (Table 1). The
MEDITS and GRUND surveys covered all the trawlable areas from the Straits of
Gibraltar to the Aegean Sea at depths between 10 to 800 meters (Fig. 1). They were
conducted each year between the end of spring and the middle of summer (MEDITS
project) and in autumn season (GRUND project). During each of the MEDITS surveys,
a total of about one thousand hauls were carried out. Each tow lasted 30 minutes at
depths of less than 200 meters. Below this limit the tows length was double. About 59%
of the total 6336 studied stations during the 11 surveys carried on from 1994 to 2004
were positioned over the continental shelves from 10 to 200 meters while the others
were allocated on the upper slope. The hauls were conducted in the same geographical
position during every yearly survey. Even though the surveys were managed aboard
different vessels with as similar as possible structural characteristics, all the involved
teams applied the same sampling methodology, including the characteristics of the gear,
its handling and the observations on the samples. The gear used for these surveys had a
small codend (20 mm, 40 mm stretched mesh for MEDITS and GRUND respectively)
and between 2 and 2.5 meters of vertical opening (BERTRAND et al., 1997; RELINI,
1998). APHIA project was carried out monthly from 1994 to 1997 and the gear used
136
had a smallest codend (3 mm, stretched mesh) (ABELLA et al., 1997). For the RAIA
TAG project a trawl net with 20 mm, 40 mm stretched cod end mesh size was used and
two sampling campaigns were performed in July- August 2001 and March-May 2002
(CATALANO et al., 2003).
Estimates of abundance indices were based on stratified random sampling
(COCHRAN, 1977), applying the stratification scheme defined for the MEDITS
programme and a swept area method. When the areas have been aggregated, the limit
between the western and eastern basins has been arbitrary fixed at the south-eastern end
of Sicily. The chondrichthyans reported in table 2 were named referring to the recent
FAO taxonomy (SERENA, 2005).
The geo-referenced information proceeding from the trawl surveys was
analysed with a geographic information system Arcview (ESRI, 1996) and maps
representing areas with different levels of density were drawn through interpolation
techniques. This more detailed analysis, however, refers only to the area between
Southern Ligurian and Northern Tyrrhenian Sea.
Moreover, the analysis of time series of the data of abundance and biomass for
some species has been carried out by the min/max autocorrelation factor analysis
(MAFA) (SHAPIRO and SWITZER, 1989), a statistical method to extract common
trend from multiple time series performed using the software package Brodgar 2.3.7
(www.brodgar.com).
Figure 1. Bottom grounds up to 800 m depth investigated by MEDITS trawl surveys
and GRUND surveys in the Italian seas.
137
Table 1. Origin of the data used in the analysis.
Project
Number
of
cruises
Number
of
stations
Period
Frequency
GRUND
1985-2004
Every year in
autumn
30
870
MEDITS
1994-2004
Every year in
spring
11
6336
APHIA
1994-1997
Every month
25
125
RAJATAG
2001&2002
July-August
& MarchApril
2
47
Geographical
areas
explored
South Ligurian
and North
Tyrrhenian
Sea
Euro
Mediterranean
Basin
South Ligurian
Sea
South Ligurian
Sea
Depth
range
sampled
(m)
10-800
10-800
0-50
0-20
Results
From 1994 to 2004, 11 surveys and 6336 MEDITS tows were performed and 45
demersal chondrichthyan species were identified in the catch: 18 sharks, 2 angelsharks,
4 stingrays, 3 skates, 14 rays, 3 electric rays and 1 rabbitfish (Table 2). Indeed, R.
montagui is probably the same species as R. polystigma; D. tortonesey is equal D.
pastinaca and R. rondeleti = R. fullonica (Serena, 2005). Single or sporadic captures
were recorded for Dasyatis centroura, Pteroplatytrigon violacea, Galeus atlanticus,
Hexanchus griseus, H. vitulus, Mustelus asterias, M. punctulatus, Rostroraja alba,
Dipturus batis, Raja brachiura, Leucoraja circularis, Leucoraja fullonica, Raja
undulata, Rhinoptera marginata, Squatina aculeata and S. squatina. For some species,
these figures reflect a true rarity (e.g. R. marginata) or possibly a depletion of the
populations (e.g. Squatina spp.) but in other cases such G. atlanticus some
misidentification problems cannot be excluded. Mobula mobular and H. nakamurai are
occasional captures (BAINO et al., 2001; BERTRAND et al., 2000).
138
Table 2. Ranked list of the chondrichthyans caught in the MEDITS, Italian GRUND
surveys and in the Northern Tuscany GRUND surveys.
139
0,1%
0,1%
0,0%
0,0%
0,0%
0,0%
13,6%
6,2%
2,1%
5,4%
7,9%
3,3%
2,9%
5,0%
9,5%
6,2%
3,7%
0,8%
0,8%
6,2%
2,5%
0,8%
1,7%
0,8%
0,1%
0,1%
0,4%
0,8%
0,0%
0,0%
GRUND
Tuscany
0,0%
0,0%
0,0%
83,9%
84,3%
77,3%
57,9%
60,7%
50,4%
49,2%
57,8%
37,6%
26,4%
31,8%
20,6%
9,9%
22,3%
33,9%
20,6%
21,9%
19,4%
21,9%
16,1%
14,1%
GRUND
Italy
27,8%
26,9%
18,5%
15,8%
8,3%
6,7%
5,0%
4,0%
4,8%
5,2%
2,4%
3,1%
2,7%
1,8%
1,7%
0,4%
0,6%
0,5%
1,8%
1,2%
0,8%
0,6%
0,2%
0,2%
0,7%
0,3%
0,1%
0,3%
0,3%
0,2%
0,0%
0,1%
0,1%
0,3%
MEDITS
Scyliorhinus canicula (Linnaeus, 1758)
Galeus melastomus Rafinesque, 1810
Etmopterus spinax (Linnaeus, 1758)
R aja clavata Linnaeus, 1758
C himaera monstrosa Linnaeus, 1758
R aja miraletus Linnaeus, 1758
Torpedo (Torpedo) marmorata Risso, 1810
R aja asterias Delaroche, 1809
D ipturus oxyrinchus Linnaeus, 1758
Squalus acanthias Linnaeus, 1758
D alatias licha (Bonnaterre, 1788)
Squalus blainvillei (R isso, 1826)
R aja polystigma Regan, 1923
C entrophorus granulosus (Bloch & Schneider, 1801)
R aja montagui cfr polystigma R egan, 1923
Torpedo (Torpedo) torpedo (Linnaeus, 1758)
Myliobatis aquila (Linnaeus, 1758)
Scyliorhinus stellaris (Linnaeus, 1758)
Mustelus mustelus (Linnaeus, 1758)
Torpedo (Tetronarce) nobiliana Bonaparte, 1835
D asyatis pastinaca (Linnaeus, 1758)
Oxynotus centrina (Linnaeus, 1758)
Leucoraja circularis Couch, 1838
H eptranchias perlo (Bonnaterre, 1788)
Leucoraja naevus Müller & Henle, 1841
Leucoraja melitensis Clark, 1926
R ostroraja alba Lacépède, 1803
R aja radula Delaroche, 1809
R aja brachyura Lafont, 1783
H exanchus griseus Bonnaterre, 1788)
D ipturus batis Linnaeus, 1758
Mustelus asterias Cloquet, 1821
Leucoraja fullonica Linnaeus, 1758
C entrophorus uyato (Rafinesque, 1810)
R aja rondeleti = Leucoraja fullonica Linnaues, 1758
Pteroplatytrygon violacea (Bonaparte, 1832)
Mustelus punctulatus Risso, 1826
D asyatis centroura (Mitchill, 1815)
Pteromylaeus bovinus (Geoffroy St-Hilaire, 1817)
R aja undulata Lacépède, 1802
Galeorhinus galeus (Linnaeus, 1758)
D asyatis tortonesei = pastinaca (Linnaeus, 1758)
Squatina squatina (Linnaeus, 1758)
R hinoptera marginata (Geoffroy Saint-Hilaire, 1817)
Galeus atlanticus (Vaillant, 1888)
Mobula mobular (Bonnaterre, 1788)
H exanchus nakamurai Teng, 1962
Squatina aculeata Cuvier, 1829
ranks
GRUND
Tuscany
(% hauls)
Species
GRUND
Italy
(% surveys)
MEDITS
(% hauls)
Frequency of occurrence
64,8%
32,1%
16,1%
31,8%
12,0%
17,0%
11,4%
10,3%
6,3%
2,9%
2,4%
2,3%
10,1%
1,1%
0,7%
4,5%
1,0%
1,5%
1
2
3
4
5
6
8
10
9
7
13
11
12
14
16
23
20
22
15
17
18
21
30
28
19
26
31
25
24
29
38
35
32
27
47
37
44
41
46
33
34
36
40
39
42
48
43
45
2
1
3
5
4
7
8
6
9
12
11
16
22
13
10
17
15
18
14
19
20
23
21
26
35
29
25
32
33
30
24
27
31
37
39
28
34
38
36
40
43
44
42
45
46
41
47
48
1
2
5
3
6
4
7
8
10
12
13
14
9
17
21
11
18
15
27
24
22
19
20
28
29
30
31
32
33
34
35
36
37
38
16
39
26
25
23
40
41
42
43
44
45
46
47
48
0,2%
0,3%
0,8%
0,7%
1,3%
0,1%
0,1%
0,2%
Only a reduced number of species have abundance levels of some commercial
interest, and only some of them are actually marketed. Most of these species are
represented by sharks of small or medium size, with an opportunistic behaviour (i.e. the
scavenger G. melastomus) or show a bathimetric distribution that extends to deeper
waters over the depth interval covered by MEDITS surveys (i.e., G. melastomus or
Etmopterus spinax). On the contrary, the high-priced and large-sized species (such as
Mustelus spp and Squalus spp.) show signs of depletion although some zones of
relatively high density were evidenced (likely in dangerous grounds usually not
explored by fishermen) (FERRETTI et al., 2005).
Some of the most common and abundant species, Scyliorhinus canicula, Raja
clavata, Galeus melastomus and Squalus acanthias, showed high frequency of
occurrence (>5% of the hauls) and abundance (> 10 kg/km2 or > 10 % of relative
biomass); the first three species also display the wider geographical distribution.
Based on the species depth distribution, MEDITS data suggest the
identification of three faunistic groups: a) the group of species more or less well
represented on all depths such as R. clavata and S. canicula; b) the group of species
showing a preference for the shelf such as D. pastinaca and M. mustelus and c) the
group of species showing a preference for the slope such as C. granulosus and E.
Spinax (BAINO et al., 2001).
From the geographical point of view, some species are abundant in all areas (S.
canicula, R. clavata, Torpedo marmorata, R. asterias, Chimaera monstrosa), while
others are most common in the west (Torpedo nobiliana, R. alba, Oxynotus centrina) or
in the east (S. acanthias, R. radula, L. naevus, R brachyura) sector of the Mediterranean
basin; some species are localised into restricted areas (H. griseus and R. miraletus in the
Tyrrhenian, M. mustelus in the Adriatic Sea, or R. brachyura and R. undulata in the
Aegean Sea). The eastern basins (Adriatic and Aegean Seas) show quite high standing
stocks biomass, mainly due to the presence of a wider continental shelf, while densities
(kg/km2) are higher in the western basins.
Figure 2. Geographical distribution of Raja clavata in the Northern Mediterranean
140
The skate R. clavata is still abundant despite its high vulnerability to the trawl
net. The persistence of good rate of catches for this species, in fact, seems to reflect a
higher ecological performance than a true resilience to exploitation. The higher biomass
concentrations (up to 100 kg/km2) are found only locally in the Gulf of Lion, Corsica,
Sardinia and Greece waters. Up 64 % of the total Mediterranean biomass is located in
the Aegean Sea, where trawling deeper than 400 m is inexistent (Fig. 2). Considering
the size at first maturity calculated for all the Mediterranean area (Mean Weight = 300 g
and Total Length = 37 cm), the Ionian Sea seems to be the most important area where
the juvenile specimens are concentrated (Table 3).
0
0
1
53
43
60
17
0
0
0
0
65
49
57
66
0
1
0
0
0
2
57
54
6
2
7
0
0
17
58
49
32
22
36
42
2
1
9
0
3
0
0
0
0
0
0
0
0
0
8
0
17
27
18
36
0
0
0
1
0
3
24
0
1
0
3
0
0
0
1
0
0
3
0
1
0
0
2
0
0
0
0
0
0
0
0
0
0
0
0
0
1
6
2
4
0
0
0
0
0
0
0
0
0
0
0
0
1
0
2
225a
0
1
0
224a
0
0
0
S Aegean Sea
0
0
0
223a
0
0
0
N Aegean Sea
221h
0
0
0
222a
221g
SW Adriatic Sea
0
5
0
Argosaronikos
221f
SW Adriatic Sea
9
0
0
E Ionian Sea
221e
SW Adriatic Sea
0
0
SE Adriatic-Alban 221i
221d
2
0
1
SW Adriatic Sea
0
10
0
221c
23
0
0
N Ionian Sea
0
0
0
221b
211c
0
22
0
N Ionian Sea
211b
N Adriatic-Slov.
0
111
0
221a
211a
Central Adriatic
15
73
0
NW Ionian Sea
134c
N Adriatic Sea
1
18
0
E Sicily
134b
Sicilian Channel
11
59
0
NE Adriatic-Croat 211d
134a
SW Tyrrhenian
0
67
2
133g
33
53
0
SE Tyrrhenian
133e
0
1
0
133f
133d
W Sardinia
0
5
0
S Sardinia
133c
NW Sardinia
1
15
2
SW Sardinia
133b
4
0
0
N Sardinia
0
36
0
133a
101
11
0
NE Sardinia
75
28
0
SE Sardinia
3
0
Centr. Tyrrhenian 132d
131a
132b
121b
NE Corsica
7
0
N Tyrrhenian Sea 132c
121a
E Gulf of Lions
0
0
0
132a
114b
W Gulf of Lions
0
0
2
1
E Ligurian Sea
114a
E Morocco
0
0
10
0
131b
113a
W Morocco
1
0
0
0
N Ligurian Sea
112a
Catalan Sea
0
0
0
SE Corsica
111a
Kg/kmq
0-50
50-100
100-200
200-500
500-800
Alicante sector
Raja
clavata
Area =
Alboran Sea
Table 3. Density, biomass and nursery location of Raja clavata in the Northern
Mediterranean
7
3
11
2
limiti = 10 - 50 - 100 - kg/kmq
Biomass in tons
0-50
0
0
50-100
0
0
100-200
0
34
200-500
0
6
500-800
0
0
0
1
0
0
0
3
0
0
6
7
92
0
0
0
29
8
39
53
0
6
1
0
0
52
0
6
1
15
0
0
0
150
0
23
0
136
0
0
0
0
0
0
0
0
2
231
25
507
69
7
3
0
0
0
0
49
3
5
0
0
47
0
14
0
3
0
19
2
56
0
30
0
16
0
67
2
260
0
17
0
0
103
0
0
0
39
0
0
0
0
2
0
0
0
0
165
20
350
908
869
10
0
0
0
1
37
50
2
4
17
0
0
10
45
24
15
9
58
44
8
1
119
0
12
0
1
0
0
0
0
0
0
0
5
0
54
163
353
645
0
1
0
2
14
0
1
0
3
0
0
0
1
0
0
1
1
1
0
0
27
0
0
0
0
0
0
0
0
0
0
0
0
0
2
50
36
91
.
0,0
.
0,0
limiti = 50 - 100 - 300 - tons
Nursey (milions of individuals with stratum average MW<300g ML<37 cm)
0-50
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
50-100
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
0,0
100-200
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
200-500
.
.
.
.
.
.
.
.
.
.
.
0,0
.
.
0,2
.
500-800
.
.
.
.
.
.
.
0,0
.
0,0
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
1,1
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
0,0
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
limiti = 0,5 - 1 - 5 million ind
This MEDITS project extends the information gathered during the GRUND
national surveys confirming the presence of juveniles in specific areas and also allows
the comparison between the different explored areas. For example, S. canicula nursery
area in the northern Tyrrhenian Sea can be compared with that off the central-eastern
Adriatic coasts (Fig. 3a, 3b). In both areas the juveniles of this species are concentrated
at about 200 m of depth (PICCINETTI pers. com.; BAINO and SERENA, 2000).
141
SIZE<…CM
SIZE
≤ 19
a
Figure 3. Scyliorhinus. canicula nursery area along the central-eastern Adriatic coasts
(a) and in the northern Tyrrhenian Sea (b).
During the 30 GRUND campaigns 870 hauls were carried out from 1985 to
2004 in the Tuscany area, 26 chondrichthyans species were caught, 1 chimaera, 10
sharks and 15 and rays skates. The species that show the higher values in number and
in weight are G. melastomus, S. canicula and R. clavata; in some cases their catches
reach 100 kg/h in yield. Besides the important information gathered regarding the
biology of the species, this project allowed to identify, for some of them, nursery and
feeding grounds. A study on the historical series of the rays catches in the northern part
of the western Mediterranean basin allowed identifying the presence of juveniles in
specific areas and depths.
In the north Tyrrhenian and south Ligurian Sea R. miraletus is distributed
between 13 and 439 meters of depth, but it is mainly concentrated between 50-150 m
(Fig. 4). Unlike other species, R. miraletus lives on bottoms with different
characteristics, from the muddy substratum to Posidonia oceanica seabed. The
population size structure obtained from the GRUND data give a figure of an important
mode on 40 cm TL but the size range is between 11-48 cm TL. The biomass and density
indices time series trend, for both GRUND and MEDITS project, show a discrepancy
between BI and DI. The exceptional captures of juvenile specimens are underlined by
the density index (DI) pick in 1999 (Fig. 5) (SERENA et al., 2005).
142
b
Raja miraletus N/Km2
Raja miraletus Kg/Km2
Figure 4. Spatial distribution in number and biomass per km2 of Raja miraletus in the
south Ligurian and North Tyrrhenian Sea.
0,6
0,5
0,4
0,3
0,2
0,1
0
-0,1
-0,2
19
85
19
86
19
87
19
88
19
89
19
90
19
91
19
92
19
93
19
94
19
95
19
96
19
97
19
98
19
99
20
00
20
01
20
02
20
03
20
04
-0,3
MAF1 ac=0,84
Variable
Biom (Kg/K m2 )
Abund (N/Km 2)
MAF1
0,6846
ns
MAF2
0,7289
0,9094
95% CI=+- 0,45
MAF2 ac=0,76
Figure 5. First and second MAFA axes for Raja miraletus. Canonical correlations
between the variables and the MAFA axes are also shown; ac = autocorrelation
of MAFA axis with time lag 1.
Following R. clavata and R. miraletus, Raja polystigma is the third most
abundant species in the trawl-surveys catches for the north Tyrrhenian Sea. It occupies a
very wide depth range (20-633 m), preferring the depths of 100-400 m, but
143
concentrating between 300-400 m (Fig. 6). Important captures of juvenile specimens
were registered between 1997 and 2000 for MEDITS and GRUND trawl surveys data
(Fig. 7) (SERENA et al., 2005).
Raja polystigma N/Km2
Raja polystigma Kg/Km2
Figure 6. Spatial distribution in number and biomass per km2 of Raja polystigma in the
South Ligurian and North Tyrrhenian Sea.
0,8
0,7
0,6
0,5
0,4
0,3
0,2
0,1
0
-0,1
-0,2
19
85
19
86
19
87
19
88
19
89
19
90
19
91
19
92
19
93
19
94
19
95
19
96
19
97
19
98
19
99
20
00
20
01
20
02
20
03
20
04
-0,3
MAF1 ac=0,95
MAF2 ac=0,72
Variable
Biom (Kg/K m2 )
Abund (N/Km 2)
MAF1
0,8763
0,9819
MAF2
ns
ns
95% CI=+- 0,45
Figure 7. First and second MAFA axes for Raja polystigma. Canonical correlations
between the variables and the MAFA axes are also shown; ac = autocorrelation
of MAFA axis with time lag 1.
144
Along a very restricted coastal zone of the south Ligurian and north Tyrrhenian
Sea, trawl surveys aimed at the Gobidae Aphia minuta stock assessment allowed to
identify and monitor important nursery, reproduction and spawning areas of R. asterias
ranging between 5-50 metres of depth (ABELLA et al., 1997). The juveniles are
concentrated in this area especially in the January-March and July-September months
(Fig. 8). On the muddy bottoms, at about 40 m of depth, the egg cases are laid all
around the year especially in spring season. After hatching, juvenile specimens quickly
reach the shore (3-7 meters of depth) (BARONE et al., in press). The RAIA TAG
project thanks to tag and release experiments of juveniles of this species made possible
to demonstrate the migration of R. asterias northwards to open sea areas and to deeper
bottoms as individuals increase their size (BONO et al., 2003; CATALANO et al.,
2003).
Depth m
20
10
30
40
Nov
n = 318
Sep
Jul
May
Mar
8
9
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
Gen
TL cm
Figure 8. Raja asterias juveniles size distribution by month in the coastal studied area
(0-50 m of depth).
Discussion
The knowledge of many biological characteristics of the cartilaginous species
(distribution, growth rates, migrations, reproduction), of their demographic structures as
well as the fisheries catching these species are very important when it is necessary to
give advice as regards management measures aimed at the reduction of the by-catch or
to protect sensible habitats and the biodiversity. In fact, the management measures
useful for the reduction of the by-catch of the cartilaginous fishes are directed to the
reduction of undesired catches of these species or alternatively to release at sea the
juveniles specimens or the adults with no commercial value when they are still in life,
but above all to avoid the fishing activities in the nurseries, breading or the spawning
areas, in the cases of ovoviviparous species, in order to preserve sensible habitat.
145
The preliminary results presented herein are only a first step toward the
implementation of a future assessment aimed at a sound management of the
Mediterranean cartilaginous fish stocks. Nevertheless, a preliminary analysis of
MEDITS data evidences clear signs of suffering for most of sharks and rays and the risk
of local extinction for some species that in the past were considered common (such as
Squatina spp.). The importance of the present results mainly relays to the fact that for
the first time data were collected using a common gear and methodology, a condition
necessary although not sufficient to implement a proper assessment program for this
important component of the marine ecosystem on a wide spatial scale.
Acknowledgments
This study was carried out with data coming from scientific trawl surveys campaigns
financed by Ministero delle Politiche Agricole e Forestali of Italy (GRUND) and
European Union (D.G. XIV) (MEDITS).
Many tanks to all the colleague participants to the data collection within the
frame of the MEDITS, GRUND, APHIA and RAIA TAG projects.
References
ABELLA A., AUTERI, R., BAINO, R., LAZZERETTI, A., RIGHINI, P., SERENA, F.,
SILVESTRI, R., VOLIANI, A., ZUCCHI, A., 1997. Reclutamento di forme giovanili
nella fascia costiera toscana. Biol. Mar. Medit. 4(1), 172-181.
ALDEBERT, Y., 1997. Demersal resources of the Gulf of Lions (NW Mediterranean).
Impact of exploitation on fish diversity. Vie et Millieu 47, 275-284.
AMORI, G., ANGELICI, F. M., FRUGIS, S., GANDOLFI, G., GROPALLI, R.,
LANZA, B., RELINI, G., VICINI, G., 1993. Vertebrata. In: A. MINELLI, S. RUFFO
and S. LA POSTA (Eds). Checklist delle specie della fauna italiana. Bologna:
Calderini, pp 1-83.
BAINO, R., SERENA, F., 2000. Valutazione di abbondanza e distribuzione geografica
di alcuni selaci dell’alto tirreno e mar ligure meridionale. Biol. Mar. Medit. 7(1), 433439.
BAINO, R., SERENA, F., RAGONESE, S., REY, J., RINELLI, P., 2001. Catch
composition and abundance of Elasmobranchs based on the MEDITS program. Rapp.
Comm. int. Mer Mèdit., 36, p. 234.
BARONE, M., DE RANIERI, S., FABIANI, O., PIRONE, A., SERENA, F., (in press).
Gametogenesis and maturity stages scale of Raja asterias Delaroche, 1809
(Chondrichthyes, Rajidae) from the south Ligurian Sea. Hydrobiologia.
BAUCHOT, M. L., 1987. Raies et autres batoides. pp. 845-886. In: FISCHER, W.,
BAUCHOT M.L. and SCHNEIDER M. (Eds). Fiches FAO d'identification pour les
besoins de la pêche. (rev. 1). Mèditerranée et mer Noire. Zone de pêche 37. Vol. II.
Commission des Communautés Européennes and FAO, Rome.
146
BERTRAND, J., GIL DE SOLA, L., PAPAKOSTANTINOU, C., RELINI, G.,
SOUPLET, A., 2000. Contribution on the distribution of elasmobranchs in the
Mediterranean (from the MEDIT surveys). Biol. Mar. Medit. 7 (1), 1-15.
BERTRAND, J., L, GIL DE SOLA, PAPAKOSTANTINOU, C., RELINI, G.,
SOUPLET, A., 1997. An international bottom trawl survey in the Mediterranean: the
MEDITS Program. ICES CM 1997/Y : 03 16.
BONO, L., DE RANIERI, S., FABIANI, O., LENZI, C., MANCUSI, C., SERENA, F.,
2005. Study on the growth Raja asterias Delaroche, 1809 (Chondrichthyes, Rajidae)
through the analysis of the vertebral sections. Biol. Mar. Medit. 12(1), 470-474
(Italian language).
CATALANO, B., MANCUSI, C., CLÒ, S., DALÙ, M., SERENA, F., VACCHI, M.,
2003. “Tag and Release” of Raja asterias juveniles in Tuscany waters: preliminary
results and future perspectives. Biol. Mar. Medit. 10(2), 789-791 (Italian language).
COCHRAN W.G., 1977. Sampling techniques. New York, John Wiley and Sons, Inc.,
3rd ed., pp 428.
ESRI, 1996. ArcView GIS. The Geographic Information System for Everyone.
Environmental System Research Institute, Inc., pp 340.
FERRETTI, F., MYERS, R.A., SERENA, F., SARTOR, P., 2005. Long-term dynamics
of chondrichthyan fish community in the upper Tyrrhenian Sea. 2005 ICES Annual
Science Conference; Theme Session on Elasmobranch Fisheries Science, 20-24
September. CM2005/N: 25.
FREDJ, G., MAURIN, C., 1987. Les poissons dans la banque de donnes medifaune.
Application a l’etude des caracteristiques de la faune ichthyologique mediterranenne.
Cybium, pp 299.
GIL DE SOLA SIMARRO, L., 1994. Ictiofauna demersal de l plataforma continental
del mar Alboran (Mediterraneo suroccidental iberico). Biol. Inst. Esp. Oceanogr.,
10(1): 63-79.
JARDAS, I., 1984. Horizontal and vertical distribution of benthos Selachia
(Pleurotremata, Hypotremata) in the Adriatic. FAO Fish. Rep. 290, 95-108.
JUKIC-PELADIC, S., VRGOC, N., KRSTULOVIC-SIFNER, S., PICCINETTI, C.,
PICCINETTI-MANFRIN, G., MARANO, G., UNGARO, N., 2001. Long-term
changes in demersal resources of the Adriatic Sea: comparison between trawl surveys
carried out in 1948 and 1998. Fisheries Research 53, 95-104.
LLORIS, D., RUCABADO, J., DEL CERRO, L., PORTAS, F., SEMESTRE, M.,
ROIG A., 1984. Tots el peixos de Mar Català. I: Llistat de cites i referéncies. Treballs
Soc. Cat. Ict. Herp. 1, 1-208.
MACECHRAN, J.D., CAPAPÉ, C., 1984. In: WHITEHEAD, P.J.P., BAUCHOT, M.L., HUREAU, J.-C., NIELSEN, J., TORTONESE, E., (Eds) 1984. Fishes of the
North-eastern Atlantic and Mediterranean (FNAM). Volume 1. UNESCO, Paris, pp
510.
BİLECENOGLU, M., TASKAVAK, E., MATER, S., KAYA, M., 2002. Checklist of
the marine fishes of Turkey. Magnolia press, Auckland. Zootaxa, 113, 1-194.
PAPAKONSTANTINOU, C., 1988. Fauna graeciae IV. Check-list of marine fishes of
Greece. Athens: NCMR – Hellenic Zoological Society, pp 257.
147
RELINI, G., 1998. Valutazione delle Risorse Demersali. Biol. Mar. Medit., 5(3) parte
prima, 3-19.
RELINI, G., BIAGI, F., SERENA, F., BELLUSCIO, A., SPEDICATO, M. T.,
RINELLI, P., FOLLESA, M. C., PICCINETTI, C., UNGANO, N., SION, L., LEVI,
D., 2000. I selaci pescati con lo strascico nei mari italiani. Biol. Mar. Medit., 7(1):
347-384.
ROUX, C., 1984. Squatinidae. In: WHITEHEAD, P. J. P., BAUCHOT, M.-L.,
HUREAU, J.-C., NIELSEN, J., TORTONESE, E. (Eds), 1984. Fishes of the Northeastern Atlantic and Mediterranean (FNAM). Volume 1. UNESCO, Paris, pp 510.
SERENA, F., 2005. Field identification guide to the sharks and rays of the
Mediterranean and Black Sea. FAO Species identification Guide for Fishery
Purposes. Rome, FAO, pp 97. 11 coulor plates+egg cases.
SERENA, F., MANCUSI, C., BARONE, M., ABELLA, A. J., 2005. Abundance and
distribution of rays in the south Ligurian and north Tyrrhenian Sea. 2005 ICES
Annual Science Conference; Theme Session on Elasmobranch Fisheries Science, 2024 September. CM2005/N: 20.
SHAPIRO, D. E., SWITZER, P., 1989. Extracting time trends from multiple monitoring
sites. Technical Report 132. Stanford University, Stanford, USA.
STEFANESCU, C., D. L-J. RUCABADO., 1992. Deep living demersal fishes in the
Catalan Sea (Western Mediterranean) below the depth of 1000 m. Journal of Natural
History 26, 197-213.
TORTONESE, E., 1956. Leptocardia, Ciclostomata, Selachii, Fauna d’Italia. Vol. II.
Ed. Calderini, Bologna: pp 334.
WHITEHEAD, P. J. P., BAUCHOT, M.-L., HUREAU, J.-C., NIELSEN, J.,
TORTONESE, E., 1984. Fishes of the North-eastern Atlantic and Mediterranean
(FNAM). Volume 1. UNESCO, Paris; pp 510.
148
Proc. of the Int. Workshop on Med. Cartilaginous Fish with Emphasis on South.- East. Med., 14-16 Oct. 06, Istanbul-Turkey
BY-CATCH OF SHARKS IN THE MEDITERRANEAN SEA:
AVAILABLE MITIGATION TOOLS
Francesco FERRETTI and Ransom A. MYERS
Biology Department. Dalhousie University. 1355 Oxford St. Halifax, NS, B3H 4J1, Canada.
E-mail: ferretti@mathstat.dal.ca
Abstract
The Mediterranean elasmobranch community is thought to suffer strong depletion in
many sectors of the basin because of fishing. The reduction of their catches is felt as a
priority. This paper reviews some example of by-catch mitigation tools available world
wide that would be effective for elasmobranch, and specifically, in the Mediterranean
basin. We talked about their potential, limitation, and finally priorities that would be
necessary to address for a better conservation of elasmobranchs in the Mediterranean
Sea.
Key words: Mediterranean Sea, by-catch, mitigation tools, legislation tools.
Introduction
The definition of by-catch is quite controversial in the scientific literature. By-catch can
refer to the portion of the capture not directly targeted by the fishers (KELLEHER,
2005). This can be retained or discarded at sea, depending on the regulation of the
fishery, and personal choice of the fishers. Usually the discarded portion is what causes
many controversies. In fact, it has a negative connotation for fishers and
environmentalists, since it burdens the fishery with a high economic, social, and moral
cost.
Elasmobranchs constitute a by-catch fraction of many fisheries around the
world (BONFIL, 1994). The low quality of their meat and the unfortunate reputation
that labels the group as man eaters, make fishers to discard these catches for more
valuable prey. However, as target fish decline in abundance and fisheries start to show
signs of sufferance in terms of production, it seems that elasmobranch fish represent
compensation for such lost. In recent years, new markets trading elasmobranch products
raised in importance (WALKER, 2004), leading many fisheries to actively pursue many
chondrichthyan stocks with catastrophic effect for the status of their populations
(WALKER, 1999).
The conservation of elasmobranchs is now a priority for the scientific
community (FAO, 1999). Many populations around the world show strong depletion
after years of fishing pressure (BAUM et al., 2003; BAUM and MYERS, 2004;
STEVENS et al., 2000; GRAHAM et al., 2001) . Limiting shark by-catch is one of the
goals of many fishery managers, who are accepting the fact that shark extirpation could
149
bring negative effects on the marine ecosystem, in spite of a long period of resource
exploitation.
This paper discusses the shark by-catch present in the Mediterranean Sea, the
available tools to limit its incidence worldwide and suggestion for future research to
cope with this problem.
The Mediterranean situation
In the Mediterranean Sea elasmobranchs constitute by-catch and target fish in
relation to the sector, type of fishery, considered species and location (MACHIAS et al.,
2001; CARBONELL et al., 2003; ANONYMOUS, 2003). What can be regarded as bycatch in more developed countries could be a vital resource in southern and eastern
countries where sharks represent a cheap fish meal. Generally there are really few
discarded species. In trawl fisheries about 46 species of demersal elasmobranchs are
commercially used (ANONYMOUS, 2003). At least 10 species of large pelagic sharks
(Prionace glauca, Alopias spp., Isurus oxyrhincus, Lamna nasus, Sphyrna zygaena,
Carcharodon carcharias, Galeorhinus galueus, Cetorhinus maximus, Carcharhinus
spp., Pteroplatytrygon violacea) are regularly caught by fisheries using long lines and
driftnets (DI NATALE, 1995, 1997; MEGALOFONOU et al., 2000; TUDELA et al.,
2005), even though the effect of drifnets probably declined after its use was restricted
by the European Community in 2001 (ANONYMOUS, 2003). Thresher sharks (Alopias
vulpinus), basking sharks (Cetorhinus. maximus), blue sharks (Prionace glauca) and
pelagic stingrays are also occasionally caught by pelagic trawlers and purse seiners
(ANONYMOUS, 2003; FROMENTIN and FARRUGIO, 2005; TUDELA, 2004).
Despite this information, it is very difficult to quantify the magnitude of shark by-catch
in the Mediterranean Sea. Elasmobranch catches are not regulated in any fisheries.
There have been few monitoring programs specifically addressing by-catch species of
any kind and even less addressing elasmobranchs. The available data are scattered in
time and space. Data on directed shark fisheries are difficult to retrieve because these
fisheries are all artisanal and at the present time located in countries that even have
trouble in developing efficient fishery management programmes for target fishes.
FAO reports 9.332 tons of shark landing for the year 2003 in the whole
Mediterranean Sea (Fig. 1) (Data extracted form Fishstat PC database). This is probably
a gross underestimation due to the discarded portion of the catches and the unmonitored
fisheries in the basin. However, by looking at the temporal trend of the landings, it is
worrying to see the sharp decline these have undergone in the last 10 years. It is likely
that the Mediterranean elasmobranch community is experiencing high levels of overexploitation. In some of its sectors, the coastal elasmobranch diversity have dropped by
more than 50 % over 50 years of fishing exploitation (ALDEBERT, 1997; JUKICPELADIC et al., 2001; FERRETTI et al., 2005). In some of these areas, elasmobranchs
showed signs of stock depletion as far back as the beginning of the last century, even
before the industrialized fishery began in the basin (FERRETTI et al., 2005). Therefore
in recent periods the attention of the scientific community has been raising to develop
conservative action in their regard. One of these would be limiting the by-catch fraction
associated with different fisheries in the basin (FAO, 1999).
150
25000
20000
tons
15000
10000
1950
1955
1960
1965
1970
1975
1980
1985
1990
1995
2000
years
Figure 1. Mediterranean elasmobranch production according to FAO statistics. Dots
represent annual landings of elasmobranchs in the basin in tons. The line is a
local regression fitted on the data to show a smooth temporal trend of the
catches.
By-catch mitigation
There is very little research on avoiding shark by-catch. Most of the by-catch
mitigation tools have been studied for turtles, birds, marine mammals and fisheries
where the amount of discards represented a clamorous portion of the production
(KELLEHER, 2005; HALL et al., 2000; HALL and MAINPRIZE, 2005).
Elasmobranchs constitute mainly undervalued species and are of little concern to the
public. This resulted in a significant lack of information with respect to their ecology,
biology and potential mechanisms to reduce their extraction from the sea. Until a few
years ago their status and rate of decline in abundance in the ocean were not really
evident and so there was no perceived problem to resolve.
However, many of these mechanisms studied for other animals, or measures
traditionally applied to manage target stocks, can be applied as well to reduce shark bycatch. These can be classified into three large groups:
•
Technological methods: modification of the fishing gear framework thought to
increase its selectivity to target fish and reduce the catchability of the unwanted
portion of the catches; actions addressed to reduce the availability of unwanted
fish stocks by the fisheries;
151
•
•
Legislative regulations: all the regulations made to reduce the wastage of
productions, and all the conservative deliberations to protect endangered
species.
Social approaches: actions addressed to improve and enhance the applicability
and the effectiveness of the first two, by working with fishers to accustom
them to these kinds of constrains in their work.
Technological mitigation tools
Some technological mitigation tools adopted world-wide could also be applied
to the most important fisheries in the Mediterranean Sea where elasmobranchs
constitute a significant portion of by-catch.
The shrimp trawl fishery is one of the most wasteful extractive practices in the
oceans. Target fish usually represent less than 20 % of the total catch and a big portion
of the by-catch is systematically discarded at sea. In the Italian waters, about 13
elasmobranch species are being taken with this practice; constituting 20 % of the total
catches (ANONYMOUS, 2003). Technological modifications of this kind of gear, to
reduce the by-catch fraction of the production, are particularly widespread around the
world. In the federal water of the Gulf of Mexico and the south Atlantic States of the
US, the production of commercial shrimp amounts to about 13 % of total production.
Most of by-catch consists of finfish, but turtles, sharks and shellfish are abundantly
caught too. The large impact that this fishery would have on the ecosystem, pushed the
US government to adopt mandatory BRDs on shrimp trawl nets. Theses devices are
components added to the trawl net to avoid the catch of unwanted species ore facilitate
their escapement once these are inside the net. Usually a strong metal grid is placed at
the beginning of the codend to avoid catches of turtle: TEDs (Turtle Exclusion
Devices). Turtles are avoided to enter the sack and an auxiliary door beside the grid
helps them to escape from the gear. With the same principle, other sorting grids or
modifications of gear netting are placed in other strategic sectors of the net. These
prevent fishes and other marine animals from penetrating the final portion of the gear
with its fine meshes, and help them to escape through large windows (Fig. 2). These
gear modifications are also largely used in Northern Europe and Australia (Square mesh
panels, Separator trawls, Nordmøre grids, etc) (BROADHURST et al., 2002). Although
these devices reduce the amount of by-catch of other species, sharks seems to barely
benefit from them. Recent analyses performed by Shepherd and Myers in the Gulf of
Mexico did not detected any mitigation in the rate of decline of many elasmobranchs
affected by this practice after the use of these devices in recent years (SHEPHERD and
MYERS, 2005).
Trawl fishing is one of the most important fisheries in the basin and many
demersal elasmobranch species are caught with this technique, though few of them are
discarded.
152
Figure 2. Example of by-catch reduction device applied to shrimp fisheries: Turtle
Exclusion Device (on the left), escaping window for fishes (on the right).
From TALAVERA, R.V. 1997.1
Modification of the net with different combinations of mesh sizes, footrope,
head-rope, sinkers, buoys, bridles to connect the doors to the beginning of the fishing
net can have a great influence on the catchability of different species. Although,
developing an extremely selective net for target fish is very difficult. The modification
of one component can increase the selectivity for a group of species with similar
behavioural and morphological characteristics but different responses to fishing
pressure. For example, to increase the selectivity of gear for flat fish the footrope can be
placed ahead of the head rope. The upper panel would be composed by larger meshes in
its initial portion. In this way, fishes that hover in the water column can easily escape
above the net, over the head-rope, or through the large meshes of its upper panel.
Alternatively, we can just reduce the vertical opening of the net. Such gears would
surely be effective for flat fish such as pleuronectiformes, skates and rays, but would not
discriminate between the two groups with certainly different sensibility to fishing
pressure. Vice versa, skates and rays and other flat fishes could be avoided by using
trawl net that don't have tight contact with the substrate, but this would exclude an
important portion of commercial catches for Mediterranean trawlers represented by
several species of soles.
By varying the dimension of the foot-rope we can influence its resistance in
rocky bottoms. Rubber discs and covers of the bottom panel of the net can allow
trawlers to exploit hard grounds by increasing the resistance of the net to its damaging
action. Therefore limitation on the diameter of the rope and on the use of these
protective devices can avoid the catch of species present in such environments.
1
TALAVERA, R.V. 1997. Dispositivos excluidores the tortugas marinas. FAO
Fisheries Technical Paper 372, FAO.
153
Midwater gears can be used instead of bottom otter trawl to force the fishers to trawl in
easily accessible grounds and thus to limit the spectrum of environments that can be
exploited in a given area (ANONYMOUS, 2004b).
Traditionally, the most used tools to manage the by-catch of trawl fisheries
remains the regulation of the net mesh size. This is the only gear regulation applied to
the Mediterranean demersal trawl fisheries, mainly addressed to reduce the juvenile
portion of the catches, which here constitute the bulk of the discard.
In longline fishing, by-catch of elasmobranch is relatively high (BONFIL,
1994). Most of the technical measures developed to reduce by-catch in this fishery are
particularly effective for these fishes. There are several gear characteristics that can
affect its selectivity: hook size, shape, soak time of the gear, depth of the hooks,
material of the gangions, and the presence of swivels to attach the gangion to the main
line. In the South Australian Shark Fishery it is prohibited the use of machines that
automatically attach and remove the hooks form the main line (WALKER, 1999). This
machine improved the efficiency of the longline fisheries around the world, by largely
increasing the umber of hooks that could be deployed at sea each fishing trip.
Prohibiting the use of these machines forced the fishers to reduce their effort and so the
number of possible catches. Coelho and co-authors demonstrated that the elasmobranch
by-catch was highly reduced in the Portuguese semi pelagic near bottom longline
fishery if the hooks close to the bottom were removed from the line (COELHO et al.,
2003). This is a particular effective by-catch mitigation tool since in their experiment it
did not decrease significantly the European hake catches, the target species for that
fishery. Forbidding the use of steel wires and adopting only nylon for the gangions
would be another improvement of longlines that would highly decrease the portion of
elasmobranchs caught, since it gives more chances to larger specimens to bite off by
cutting the line.
With gillnets, modifying mesh size can effectively reduce the portion of
juvenile specimens that remain entangled in the net (CARLSON and CORTES, 2002).
Buenquerpo and co-authors showed significant differences in the mean size of sharks
caught by longlines and gillnets fishing in common areas. For several species of sharks,
gillnets caught mainly bigger specimens than longlines did (BUENQUERPO et al.,
1998). Also by modifying the breaking strain of the webbing filament, large sharks
could escape when entangled by breaking the net (WALKER, 2004). In the Bass Strait,
a selection of the mesh size of about 15 cm in the Mustelus antarticus fishery allowed a
sustainable use of this resource by ensuring escapement of small and large animals, and
exploiting only middle sized specimens, which occur far from inshore areas where
pregnant female and juveniles concentrates (WALKER, 1998).
The use of lights attached on driftnets can aid in gear recognition at night.
Although the practice can bring gillnet fishery to extend its activity at 24 hours a day,
the use of such lights can alternatively help fishers recognize their nets which will
prevent leaving unattended gears for several days. There would be a reduction of shark
wastage and spoilage due to fish and other animals, and there would be a reduction of
ghost fishing since lost gears would be easily detected end removed from the sea.
154
Instead of improving the selectivity of the fishing gear, technological measures
can be addressed to reduce the availability of sensible stocks to the fisheries. Marine
protected areas would be efficient tools to manage elasmobranch fishes. These can
constitute refuge for depleted stocks, which can use such portions of the ocean as
recruitment zones for adjacent exploited regions, and thus allowing a longer exploitation
of the resource. In the Italian coasts, zones such as the northern Tyrrhenian Sea and the
Sicilian Channel are areas of high elasmobranch diversity, but also of high fishing
pressure. However, this pressure is highly skewed toward the Italian portion of the
sectors, leaving Corsica and Tunisia comparatively underexploited coasts. The
closeness of the coasts, and the bathymetric contiguity of the seabed within each area,
could have allowed the persistence of many elasmobranch species in the regions, as
sharks could recruit from low fishing pressure grounds acting as natural marine
protected areas. The utility of MPAs as fishery management tools still need to be tested
properly, but there is evidences that these could be particularly beneficial for
elasmobranchs, especially on the light of case studies showing persistence of shark
species attributable to recruitment from unexploited fishing grounds (GRAHAM et al.,
2001; WALKER, 1998).
Temporary closure of fishing areas would be effective tools to reduce fishing
pressure on critical stages of the life history of a given species, e.g. during spawning and
mating season or in sectors where juvenile aggregate and growth before reaching their
sexual maturity. Such measures can range from total closures and restriction of any
fishing practice, to forbidding the use of some gear in some determinate period. They
can range from day/night, monthly or seasonal closures, depending on the particular
situation of the managed fishery. Estuarine environments have been recognized as
preferential spawning ecosystem for many sharks. The closure of such sectors of the
coast would prevent the disruption of critical ecosystems for elasmobranch fishes and
prevent the exploitation of pregnant adult females and juvenile specimens. However
these areas must be identified beforehand. The best way to do it is through the scientific
campaigns of evaluation of the resources (SERENA and RELINI, in this volume)
Instead of area closures, a more dynamic approach could be developing a
system of information sharing among fishers. Each time a vessel encounter a spot with
an elevate proportion of by-catch, that would be communicated to other components of
the fishery, and that area would be avoided in the immediate period. This practice is
called hot-spot reporting. It has been undertaken by fishers of the Bering Sea. In this
area, a private contractor gathers all the information coming from fishers and analyzes
such data to provide an immediate estimate of the distribution of the catches per vessels
in the fishery (HALL and MAINPRIZE, 2005).
Legislative tools
In some fishery the application of individual or collective quota has been a
good response to limit by-catch. Individual quota limits the number of by-catch species
that a particular vessel can report for each fishing trip or season. Collective quota
enlarge such limit to the entire fishery, but can have the advantages to push fishers to
155
limit their individual catches through a “peer” effect (pressure that other fishers exercise
to the ones that produce the major portion of unwanted catches).
Some nations have adopted discard and by-catch bans. In Norway where size
limitations exist, fishers are forced to keep all their catches, even if these are constituted
by juvenile specimens. In this way the discard portion of the production can be
recorded. Fishers can not sell their discard but this is being auctioned and the earnings
can not be taken by the producing parts. In this way, there is surely an improvement of
the estimation of fishing mortality, useful for several managerial purposes, but also
there is an improvement on the fisher's acceptance of eventual fishing gear
modifications to reduce by-catch. Similar policies have been adopted by other countries
with bigger or lesser variation from the above described scheme. In Canada the landed
by-catch counts against quota. In New Zealand and Iceland, the quota reduction
produced by the landed by-catch portion is only 50 % (HALL and MAINPRIZE, 2005).
Such measures could be particularly relevant for shark by-catches, especially where
finning is practiced. The obligation to retain carcasses would amply reduce the amount
of sharks killed each fishing trip given the space limitations of the boats.
Social work
It is implicit that all measures of by-catch mitigation are usually costly for
fishers and for agencies. The application of gear regulation can largely affect the
production of target fish. Marine protected areas and area closures reduce the overall
effort that the fishery deploys in a zone and limits its spectrum of available resources.
The collaboration of fishers would be extremely helpful for the success of these
measures. By their responsible behaviour, they can avoid and buffer many of the
drawbacks of current regulations. For example, the application of quotas or discard bans
can really be effective in pushing fishers to adopt modifications that increase gear
selectivity to target fish, and make them avoid hot spots of high by-catch. However,
these can also produce a new-market for by-catch species, and push fishers to not record
their catches. To be effective in reducing shark by-catch, the agencies need to put a
great effort in training programs for resource users. These programs would be used to
explain them the importance of conserving such species, the possible problems that their
elimination could bring to the ecosystem and to the persistence of fishing activities.
One of the problems of shark conservation is the lack of detailed information
about their extraction from the oceans. Fishers represent a continuous sampling force in
the marine environment. The success of catch monitoring programs through the use of
log-books requires a great deal of fisher’s time, which, without their understanding of
the utility of such practice, would be difficult to obtain. Fishery agencies must provide
them all of instruments needed to register catches in the easiest and least time
consuming manner. Laminated identification cards, posters, and any other easily usable
format helping fishers to recognize the species with relative ease in fishing time
condition, are preferable to cumbersome and complicated books.
Finally, the success of conservation programs comes after the public has taken
a vested interest. Sharks, unfortunately, have a great handicap in this aspect due to their
bad reputation, but it is the job of conservation and fishery agencies to find the best
156
communicative tools to put sharks closer to the concerns of people and to let them
understand the gravity of losing such important animals. Under the pressure of
environmentalist and Non Governmental Organizations, a great effort has been made for
dolphins and for turtles, even though these animals are not of great commercial value.
Most of the researches on mitigation tools have been funded in that direction respect to
the plight of elasmobranchs.
Problems and priorities
All of the above mentioned mitigation tools are expensive (both as direct costs
and as loss of profit), and therefore worth careful consideration before implementation.
This is particularly true for species, such as sharks and rays, which don't have a high
market value. The loss of elasmobranch will not immediately affect revenue from
fisheries, although the cost of the above mentioned mitigation tools will represent an
immediate cost for fishermen. However, given their actual status, it is without doubt that
sharks require conservation. Considering the economic and social cost this would bring,
it is necessary to ensure all of the actions are extremely effective, and address the
components, which most affect their resistance to extirpation. For this purpose, it is
required an extensive amount of data on species distribution, abundance, movement,
fishing mortality, interaction between species and sensitivity to fishing gears. For
sharks, unfortunately this is not the case, especially in Mediterranean where the paucity
of data is extremely evident.
At the present, the Mediterranean Sea requires a clear understanding of the
status of its elasmobranch community. The basin it is still lacking a compendium
showing the distribution of species in its different sectors, relative abundance between
areas, and absolute abundance within areas in relation to fishing pressure. Some
description have been done in the northern part of the basin from trawl and pelagic
surveys (BERTRAND et al., 2000; RELINI et al., 2000; MEGALOFONOU et al.,
2000), but the southern and eastern part of the basin still remain unassessed. It is need to
identify the characteristics of the pristine Mediterranean marine ecosystem, and analyze
what has changed, why, and what the ultimate effects of such changes are in relation to
our use of resources. There is a clear difference in elasmobranch diversity between the
north-western and south-eastern part of the basin. In the north-western basin we find
most of the elasmobranch population showing signs of depletion (ALDEBERT, 1997;
JUKIC-PELADIC et al., 2001; FERRETTI et al., 2005) while in the south-eastern
sector many populations are still in their pristine state (most will be shown in this
volume). The influence of fishing is quite evident, since there is a clear gradient
between the two zones, going from more exploited zones in the northwest, to almost no
disturbed areas in the southeast. Environmental differences may be also pertinent, but
more likely negligible by taking into account the relative small geographical scale of the
basin and the much greater effects of fishing pressure. This, however, has to be tested
and quantified, in order to identify the correct tools to manage the region.
At present, the best conservation tool to apply to elasmobranch populations
would be data analysis. It is necessary for each country to cooperate in a regional
management by developing a common database, where any kind of information
157
regarding elasmobranch catches, fishery effort, biological, and ecological information
would come from every sector of the basin, and be widely accessible to the whole
scientific community. Fishery data need to be combined together by using all of the
statistical tools available at the moment, to produce estimates of actual abundance and
trends over time. This is needed to produce a research baseline on which will be
possible to refer for future effective conservation actions. To obtain an accurate
assessment of the historical condition in the Mediterranean, it is essential to enlarge the
temporal and spatial scales of the present investigations. Most analyses to date are
representative of very small regions over short period of time. By focusing on small
sectors of the basin, these observation are constrained in their potential to explain
general and more meaningful patterns. By combining data over regions and time, it
would be possible to piece together the historical condition of the Mediterranean, and
develop an understanding of the patterns of change. An historical approach will likely
change the current outlook on the baseline abundance of many species.
With sound data analyses, unequivocally quantifying the reality of the
situation, come conservation actions. The research performed by Baum and colleagues
in the northwest Atlantic and Gulf of Mexico, on the status of elasmobranch populations
occurring in these areas (BAUM et al., 2003; BAUM and MYERS, 2004), has already
resulted in conservation actions that will protect global shark populations, such as the
listing of the oceanic white tip shark as “critically endangered" by the World
Conservation Union (IUCN) (ANONYMOUS, 2004a) and the recently announced ban
of shark finning in international waters of the Atlantic (BURDEAU, 2004).
In Mediterranean Sea, 14 nations have so far ratified The Barcelona
Convention, an international agreement for the protection of the Mediterranean sea
against human induced degradation of the marine ecosystem. Within the convention,
three species (Carcharodon carcharias, Cetorhinus maximus and Mobula mobular) are
enlisted as endangered and threatened. These should receive full protection against
killing, trade, transport and exposition of specimens and their product. It is likely that a
broad scale analysis of shared information on elasmobranch extraction, coming from all
the sector of the basin, could really lengthen this list and promote immediate
conservation actions.
Acknowledgments
The participation of Francesco Ferretti was founded by RAC/SPA. We would like to
thanks Bernard Seret and Fabrizio Serena for their useful comments and suggestions on
the improvement of the manuscript. We also thanks Daniel Cebrian, Bayram Ozturk and
all the other organizers of the workshop for their kind invitation, hospitality and to have
made that event happen. It was an extremely important meeting for the development of
the conservation process of the Mediterranean Sea resources, which urgently need the
cooperation of all their users.
158
References
ALDEBERT, Y., 1997. Demersal resources of the Gulf of Lions (NW Mediterranean).
Impact of exploitation on fish diversity. Vie et Milieu 47(4), 275-285.
ANONYMOUS, 2003. Commission staff working paper report of ad working group
elasmobranchs fisheries. Technical report, Commission of the European
Communities, pp 207.
ANONYMOUS, 2004a. More sharks in the red list.
http://www.flmnh.ufl.edu/fish/organizations/ ssg/ssgiucnmeet2004.htm.
ANONYMOUS, 2004b. The Pacific coast groundfish fishery management plan bycatch
mitigation program final environmental impact statement. NOAA Fisheries (National
Marine Fisheries Ser- vice). http://www.nwr.noaa.gov/1sustfsh/groundfish/eis
BAUM, J., MYERS, R.A., 2004. Shifting baselines and the decline of pelagic sharks in
the Gulf of Mexico. Ecol. Lett. 7(2): 135-145.
BAUM, J. K., MYERS, R. A., KEHLER, D. G., WORM, B., HARLEY, S. J.,
DOHERTY, P. A., 2003. Collapse and conservation of shark populations in the
Northwest Atlantic. Science 299, 389-392.
BERTRAND, J., DE SOLA, G., PAPAKOSTANTINOU, C., RELINI, G., SOUPLET,
A., 2000. Contribution on the Distribution of Elasmobranchs in the Mediterranean
(from the MEDIT Surveys). Biol. Mar. Medit. 7(1), 385-399.
BONFIL, R. 1994. Overview of world elasmobranch fisheries FAO Fisheries Technical
Paper 341,FAO.
BROADHURST, M., KANGAS, M., DAMIANO, C., BICKFORD, S., KENNELY, S.
2002. Using composite square-mesh panels and Nordmøre-grid to reduce bycatch in
the Shark Bay prawn-trawl fishery, Western Australia. Fish. Res. 58, 349-365.
BUENQUERPO, V., RIOS, S., MORON, J., 1998. Pelagic sharks associated with the
swordfish, Xiphias gladius, fishery in the eastern North Atlantic Ocean and the Strait
of Gibraltar. Fish. Bull. 96, 667-685.
BURDEAU, C., 2004. Protection for Atlantic sharks. The Associated Press.
CARBONELL, A., ALEMANY, F., MERELLA, P., QUETGLAS, A., ROMAN, E.,
2003. The by-catch of sharks in the western Mediterranean (Balearic Islands) trawl
fishery. Fish. Res. 61, 7-18.
CARLSON, J., CORTÉS, E. 2002. Gillnet selectivity of small coastal sharks off the
Southeastern United States. Fish. Res. 60, 405-414.
COELHO, R., BENTES, L., MS GONÇCALVES, J., G LINO, P., RIBERIO, J.,
ERZINI, K., 2003. Reduction of elasmobranch by-catch in the hake semipelagic nearbottom longline fishery in the Algarve (Southern Portugal). Fish. Sci. 69, 293-299.
DI NATALE, A., 1995. A review of drifnet catches by the Italian fleet: species
composition, observers data and distribution along the net. ICCAT. Col. Vol. Sci. Pap,
44(1), 226-235.
DI NATALE, A., 1997. By-catch of shark species in surface gear used by the Italian
fleet for large pelagic species. ICCAT, SCRS/97/118, pp 138-140.
FAO. 1999. International Plan of Action - Sharks. Food and Agriculture Organisation of
the United Nations, Committee on Fisheries, Rome.
159
FERRETTI, F., MYERS, R.A., SARTOR, P., SERENA, F., 2005. Long term dynamics
of the chondrichthyan fish community in the upper Tyrrhenian Sea. In ICES CM
2005. Annual Science Conference. Themesession N on Elasmobranch Fisheries
Science. September 20-24. Aberdeen, UK. ICES.
FROMENTIN, J., FARRUGIO, H., 2005. Results of the 2003 observer program on
board the French purse seiner targeting Atlantic bluefin tuna in the Mediterranean
Sea. ICCAT Col. Vol. Sci. Pap. 58(2), 779-782.
GRAHAM, K., ANDREW, N., HODGSON, K., 2001. Changes in relative abundance
of sharks and rays on Australian south east fishery trawl grounds after twenty years of
fishing. Mar.& Freshwater Res. 52, 549-561.
HALL, M., ALVERSON, D., METUZALS, K., 2000. By-catch: problems and
solutions. Mar.ine Pollut. Bull. 41(1-6), 204-219.
HALL, S., MAINPRIZE, B., 2005. Managing by-catch and discards: how much
progress are we making and how can we do better? Fish and Fish. 6:, 134-155.
JUKIC-PELADIC, S., VRGOC, N., KRUSTULOVIC-SIFNER, S., PICCINETTI, C.,
PICCINETTI-MANFRIN, G., MARANO, G., UNGARO, N., 2001. Long-term
changes in demersal resources of the Adriatic Sea: comparison between trawl surveys
carried out in 1948 and 1998. Fish. Res. 53, 95-104.
KELLEHER, K., 2005. Discards in the world's marine fisheries. FAO Fisheries
Technical Paper, FAO, pp 470.
MACHIAS, A., VASSILOPOULOU, V., VATSOS, D., BEKAS, P., KALLIANIOTIS,
A., PAPACONSTANTINOU, C., TSIMENIDES, N., 2001. Bottom trawl discards in
the northwestern Mediterranean Sea. Fish. Res. 53, 181-195.
MEGALOFONOU, P., DAMALAS, D., YANNOPOULOS, C., DE METRIO, G.,
DEFLORIO, M., DE LA SERNA, J., MACIAS, D. 2000. By-catches and discards of
sharks in the large pelagic fisheries in the Mediterranean Sea. Final report of the
project no 97/50 dg xiv/c1, Community of Mediterranean Universities.
RELINI, G., BIAGI, F., SERENA, F., BELLUSCIO, A., SPEDICATO, M., RINELLI,
P., FOLLESA, M., PICCINETTI, C., UNGARO, N., SION, L., LEVI, D., 2000. I
Selaci Pescati con lo Strascico nei Mari Italiani. Biol. Mar. Medit. 7(1), 347-384.
SERENA, F., RELINI G. Use of scientific campaigns (Trawl Survey) for the knowledge
of the sensitive habitats. Reviw of the MEDITS, GRUND and APHIA data with
special attention to the Italian seas. Proceedings of Workshop on Mediterranean
Cartilaginous Fish with emphasis on Southern and Eastern Mediterranean Istanbul,
Turkey 15-16 October 2005 (Submitted).
SHEPHERD, T., MYERS, R.A., 2005. Direct and indirect fishery effects on small
coastal elasmobranchs in the northern Gulf of Mexico. Ecol. Lett. 8, 1095-1104.
STEVENS, J.D., BONFİL, R., DUVLY, N.K., WALKER, P.A. 2000. The effects of
fishing on sharks, rays, and chimaeras (chondrichthyans), and the implications for
marine ecosystem ICES J. Mar. Sci., 57: 476-494.
TALAVERA, R.V., 1997. Dispositivos excluidores the tortugas marinas. FAO Fisheries
Technical Paper 372, FAO.
160
TUDELA, S., 2004. Ecosystem effects of fishing in the Mediterranean: an analysis of
the mayor threats of fishing gear and practices to biodiversity and marine habitats.
Studies and Reviews 74, FAO, GFCM.
TUDELA, S., KAI KAI, A., MAYNOU, F., ANDALOSSI, M., GUGLIELMI, P., 2005.
Driftnet fishing and biodiversity conservation: the case study of the large-scale
Moroccan driftnet fleet operating in the Alboran Sea (SW Mediterranean). Biologiol.
Conserv. 121, 65-78.
WALKER, T., 1998. Can shark resources be harvested sustainably? Mar.& Freshwater
Res. 49, 553-72.
WALKER, T., 1999. Southern Australian shark fishery management. In: Case studies of
the management of elasmobranch fisheries. FAO Fisheries Technical Paper 378/2,
FAO.
WALKER, T., 2004. Management measures. In: MUSICK, J.K and BONFIL, R. (Eds),
Elasmobranch Fisheries Management Techniques. APEC secretariat, pp 285-321.
161
Proc. of the Int. Workshop on Med. Cartilaginous Fish with Emphasis on South.- East. Med., 14-16 Oct. 06, Istanbul-Turkey
CHONDRICHTHYES IN CYPRUS
Myroula HADJICHRISTOPHOROU
Senior Fisheries and Marine Research Officer, Department of Fisheries and Marine Research, Cyprus.
E-mail: andrecws@logos.cy.net
Abstract
In Cyprus 28 species of shark and dogfish and 17 species of skates and rays have been
recorded. The paper lists these species with information on the area they were recorded
in, as well as depth and frequency. The catches of these species from 1980 to 2004 are
given, as are the relative impacts of the various fisheries on them. Indications on the
state of the stocks of these fishes are also given where possible.
Key words: Cyprus coasts, fisheries, landings.
Introduction
In Cyprus there is little consumption of cartilaginous fishes. Only some skates and rays
and some dogfishes are of commercial interest. These are mainly caught by the inshore
fishery, with trammel nets and bottom-set long-lines and by the trawl fishery. These are
not targeted for, in any fishery, but are by-catch. Sharks are not fished for either, but
form a small by-catch of surface long-lining for swordfish. A few species are of some
very limited commercial interest.
The study of these species on the island has so far been incidental to other fish
studies. Some of the information on the species comes from the systematic catch
sampling programme of the Department of Fisheries, in the inshore and trawl fisheries.
The main sources of statistical data on catches are the Annual Reports of the
Department of Fisheries (DEMETROPOULOS, 1980-1989). These reports in fact
extend back to 1967 and include detailed statistics on catches and fishing effort data.
The Annual Reports of the Department were discontinued in 1990 but fishery statistics
continued being collected and the Department has been compiling statistical reports on
the Cyprus Fisheries since then (DEPARTMENT OF FISHERIES, 1990-2004).
Records of Chondrichthyes in Cyprus
The species of cartilaginous fishes recorded in Cyprus are presented in Table 1
and consist of 28 species of shark and dogfish and 17 species of skates and rays. These
records cover the whole island. Some of the species listed need confirmation.
Unconfirmed reports from local sources are marked with an asterisk (*).
The main sources of information are DEMETROPOULOS and NEOCLEOUS
(1969), GILAT and GELMAN (1984), FISCHER et al. (1987), COMPAGNO (1984a, b),
MCEACHRAN and CAPAPÉ (1984) and (SERENA, 2005), with some unpublished
162
information provided by A. Demetropoulos on one new species and in listing doubtful
species (DEMETROPOULOS, pers. comm.). The CLOFNAM classification was used
(HUREAU and MONOD, 1973).
Table 1. Records of Chondrichthyes in Cyprus
Species
Local
name
Common English
name
Area
recorded
Freq.
Depth
(m)
FB,MB
Occ.
50
NC,WC
Com.
100-200
CW
Com.
80-500
Gulper shark
Occ.
1490
Velvet belly lantern
shark
Occ.
1490
Angular roughshark
Rare
HEXANCHIDAE
Heptranchias perlo (1)
Skyllopsaro
Hexanchus griseus (1)
Bambakaris
SQUALIDAE
Squalus acanthias (1)
Squalus blainville (5)
CENTROPHORIDAE
Centrophorus granulosus
(2)
ETMOPTERIDAE
Acanthias
Skyllaki
Etmopterus spinax (2)
OXYNOTIDAE
Oxynotus centrina (3)
SQUATINIDAE
Squatina squatina (1)
Gatos
Squatina oculata (5)
Gatos
ODONTASPIDIDAE
Carcharias taurus (1)*
Odontaspis ferox (1)*
ALOPIDAE
Alopias vulpinus (1)
LAMNIDAE
Carcharodon carcharias
(5)
Isurus oxyrinchus (1)
Lamna nasus (1)
SCYLIORHINIDAE
Sharpnose sevengill shark
Bluntnose six-gill
shark
Piked dogfish
Longnose spurdog
Angel shark
Smoothback
angelshark
CW
Occ.
Karcharias
Skyllopsaro
Sand tiger shark
Fierce shark
MB, NC
NC
Rare
Rare
Aloupos
Thresher shark
NC
Rare
EP
Karcharias
Great white shark
Skyllopsaro
Skyllopsaro
Shortfin Mako
Porbeagle
NC,WC
AB
Occ.
Rare
EP
EP
FB
Occ.
40
CW
Com.
20-60
Galeus melastomus (1)
Scyliorhinus canicula (1)
Skyllaki
Scyliorhinus stellaris (4)
TRIAKIDAE
Galeorhinus galeus (4)
Galeos
Mustelus asterias (1)
Drositis
Mustelus mustelus (1)
Galeos
Mustelus punctulatus (4)
Galeos
Blackmouth catshark
Small spotted catshark
Nursehound
Tope shark
Starry smoothhound
Smooth-hound
Blackspotted
smooth-hound
163
WC
Occ.
20
EB
Occ.
60/80
Table 1 (Cont.)
CARCHARHINIDAE
Carcharhinus brevipinna
(4)
Carcharhinus
melanopterus (5)
Carcharhinus plumbeus
(4)
Prionace glauca (1)
SPHYRNIDAE
Skyllopsaro
Spinner shark
Skyllopsaro
Black-tip reef shark
Skyllopsaro
Sandbar shark
Karcharias
Blue shark
Sphyrna zygaena (1)
Zygaena
Sphyrna mokarran (4)
Rhinobatus rhinobatus{1)
Zygaena
Viola
Rhinobatos cemiculus (6)
Viola
TORPEDINIDAE
Torpedo marmorata (1)
Torpedo nobiliana (1)
Torpedo torpedo (1)*
RAJIDAE
Dipturus oxyrinchus (1)
Raja asterias (1)*
Raja clavata (1)
Smooth
hammerhead
Great hammerhead
Common guitarfish
Blackchin
guitarfish
NC
Occ.
Rare
EP
NC,LB
Occ.
15
Moudiastra
Moudiastra
Moudiastra
Marbled electric ray
Dark electric ray
Electric ray
FB
FB
Occ.
Occ.
60/70
60/70
Vati
Vati
Vati
Long-nosed skate
Starry ray
Thornback ray
MB
Occ.
400
150-300
Vati
Brown ray
Occ.
150-300
Raja radula (1)
Vati
Rough ray
EB,FB, AB
EB,FB,
MB
EB,FB,
MB
Com.
Raja miraletus (1)
Occ.
100-220
Vati
Vati
Roughtail stingray
Common stingray
CW
Com.
Vati
Blue stingray
Vati
Spiny butterfly ray
Aetopsaro
Bullnose ray
NC
Occ.
DASYATIDAE
Dasyatis centroura (6)
Dasyatis pastinaca (1)
Pteroplatytrygon violacea
(1)*
GYMNURIDAE
Gymnura altavella (1)
MYLIOBATIDAE
Pteromylaeous bovines (1)
RHINOPTERIDAE
Rhinoptera marginata (6)
MOBULIDAE
Mobula mobular (1)*
20
Lusitanian cownose
ray
Manta ray
Sources of identification/record: (1) Demetropoulos and Neocleous (1969), (2) Gilat and Gelman (1984),
(3) Demetropoulos (pers. Comm.), (4) Compagno (1984) (part 1), (5) Compagno (1984) (part 2), (6)
McEachran and Capapé (1984). Abbreviations: AB - Akrotiri Bay (Limassol Bay); CW - Cyprus Waters; EBEpiskopi Bay, FB - Famagusta Bay; MB - Morphou Bay; WC - West Coast; NC - North Coast; LB - Larnaca
Bay; EP - Epipelagic
164
Fisheries
Table 2 and Figure 1 show catches in the area under the control of the
government. Fishermen are required to report sharks and rays separately in their
statistical returns in all fisheries.
The Swordfish Fishery
The annual catch of sharks in surface long-line fishing varies with a fluctuating
fishing effort. At its peak in the late 1980s and early 1990s catches peaked at 34 tons in
1990 and dropped to about 10 tons p.a. since 1995. On average, sharks form about 10%
of the total catch of the swordfish fishery. The figures for 2003 and 2004 show a
practically zero catch and this is related to the drastic drop of fishing for swordfish, as
the stocks of this fish are evidently very low and little fishing takes place. Annual
catches may in fact have been higher, as many sharks, of some species at least, are
discarded at sea, as they fetch very low prices or are not marketable at all, so in effect
the figures in Table 2, reflect landings rather than catches. In Cyprus fish from the local
fisheries is mainly sold fresh and the fact that shark meat cannot keep for any length of
time (due to the presence of high levels of urea in the blood and its breakdown to
ammonia which contaminates the meat,) make their marketing more of a problem.
The data for the swordfish fishery (i.e., for the sharks) are deemed to be more
accurate than those of the inshore fishery though fluctuations and trends in fishing effort
need to be linked to these data to make them more meaningful – and possibly reveal
changes and trends in populations. This is currently being done.
The Inshore (artisanal) Fishery and the Trawl Fishery
These fisheries catch mainly dogfish, skates and rays. Catches of sharks are
rare and often reach the newspapers and other media. The catches of skates, rays and
some of the dogfishes, which are fished by the trawl and inshore fisheries, are in part at
least marketed. Table 2 and Figure 1 show the landings of these species. The catches
reflected in the statistics, of the inshore fishery in particular, vary considerably, with
peaks up to 156 tons, in the period between 1985 and 1990. There is, however, some
doubt as to the credibility of these data - especially of those in peak years - due to the
sample boat system used to calculate the landings of the inshore fishery and the
willingness of fishermen to report such catches. As there have not been any marked
changes in fishing effort in the trawl fishery, at least during the period covered by the
present study, and a steady (if rapid) increase in the inshore fishery, the main source of
bias would be expected to come from statistical errors. Nonetheless, the dramatic
changes in fishing effort in the immediately preceding period (i.e., 1975-1980,
following the 1974 events in the country), are very likely to have impacted seriously the
populations - and catch rates - of these species during the period under review. This is
no doubt accentuated by the fact that the species concerned are long-living species, the
populations of which are unable to recover quickly, even if they benefited from any of
the conservation measures taken in 1981/82 and later (extension of the closed period for
trawling, freezing of the capacity of the trawl fishery, etc). It needs to be noted here, that
165
the trawl fishery in Cyprus waters is currently being reduced by a license buy-back
programme and the fishery is now (in 2005) already operating at about 50 % of its
capacity, with the vessels, whose licenses are withdrawn, being scrapped.
Table 2. Catches of Chondrichthyes in Cyprus
Year
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
Total
Average
Catches in Cyprus waters - in tons
Swordfish Fishery
Inshore and Trawl Fisheries
6,5
19
8,4
17,5
17,5
16,2
3,9
13,3
9,3
18
5,9
55,1
12
137,7
16,9
32,5
18,3
90,2
18,8
157,5
33,8
9,4
13,3
6,7
9,7
23,6
15,5
30
24,6
16,4
13,6
19,5
8,4
13,4
8
16,1
10,6
9,8
11,6
3
8,8
13,2
8
18,4
8,7
8
1,5
7,8
0,6
5,4
294,2
11,77
757,7
30,31
166
180
160
140
120
100
80
60
40
20
0
Swordfish Fishery (Sharks)
Trawl and Inshore Fisheries
(Dogfishes, Skates, Rays)
19
80
19
82
19
84
19
86
19
88
19
90
19
92
19
94
19
96
19
98
20
00
20
02
20
04
Catch in tons
Figure 1. Chondrichthyes - Catches 1980 to 2004
Year
Figure 1. Catches of Chondrichthyes in Cyprus.
Discussion
The fishery statistics show a drop in catches of most Chondrichthyes in Cyprus waters
over the last 25 years. The drop may be partly attributed to statistical inaccuracies, but
most likely they reflect also a real drop in stocks. The state of individual species is even
more difficult to assess. Nonetheless there are indications that the stocks of some noncommercial species, such as that of the bluntnose six gill shark, are little impacted. On
the other hand shark species that form a regular by-catch of surface longlining are more
at risk from intensive fishing and may well follow the fate of the swordfish stocks that
are now in a near collapsed state. The recent drastic reduction of surface longlining for
swordfish is likely to benefit the stocks of the sharks caught by this method. The drastic
reduction of the trawl fishery is also expected to benefit the stocks of dogfishes, skates
and rays, which are exploited by this fishery.
A more focused study of Chondrichthyes in Cyprus will no doubt provide
insight into the state of these species and of the effects of the measures taken (reduction
of the trawl fishery) and of the de facto drop in surface longlining.
References
COMPAGNO, L. J. V., 1984a. FAO species catalogue. Vol. 4. Sharks of the world. An
annotated and illustrated catalogue of shark species known to date. Part 1 Hexanchiformes to Lamniformes. FAO Fish. Synop. 125(4/1), pp 1-249.
167
COMPAGNO, L. J. V., 1984b. FAO species catalogue. Vol. 4. Sharks of the world. An
annotated and illustrated catalogue of shark species known to date. Part 2 Carcharhiniformes. FAO Fish. Synop. 125(4/2), pp 251-655.
DEMETROPOULOS, A., 1980-1989. Annual Report on the Department of Fisheries
and the Cyprus Fisheries. Department of Fisheries, Ministry of Agriculture and
Natural Resources. Cyprus.
DEMETROPOULOS, A., NEOCLEOUS D., 1969. The Fishes and Crustaceans of
Cyprus. Dept. of Fish. Fisheries Bulletin No. 1, pp 21.
DEPARTMENT OF FISHERIES, 1990-2004. Annual Report on the Cyprus Fisheries.
Department of Fisheries (Department of Fisheries and Marine Research), Ministry of
Agriculture and Natural Resources. Cyprus.
FISCHER, W., BAUCHOT, M.-L., SCHNEIDER, M., 1987. Fiches FAO
d'identification des especes pour les besoins de la peche. Mediterranee et mer Noire
(Zone de peche 37). Rome.
GILAT. Ε., GOLMAN, A., 1984. On the shark and fishes observed using underwater
photography during a deep water cruise in the eastern Mediterranean. Fish. Res. 2,
257-271
HUREAU, J.-C., MONOD, TH. (Ed.), 1973. Check-list of the fishes of the northeastern Atlantic and of the Mediterranean (CLOFNAM): Vol. I&II. UNESCO, Paris,
France.
MCEACHRAN, J.D., CAPAPÉ, C., 1984. Dasyatidae. In: P.J.P. Whitehead, M.-L.
Bauchot, J.-C. Hureau, J. Nielsen and E. Tortonese (eds.) Fishes of the north-eastern
Atlantic and Mediterranean. UNESCO, Paris. Vol.1, pp 197-202.
SERENA, F., 2005. Field identification guide to sharks and rays of the Mediterranean
and Black Sea. FAO Species Identification Guide for Fishery Purposes. Rome, pp 93.
10 colour plates.
168
Proc. of the Int. Workshop on Med. Cartilaginous Fish with Emphasis on South.- East. Med., 14-16 Oct. 06, Istanbul-Turkey
A SUMMARY OF SHARK BY-CATCH IN THE
ITALIAN PELAGIC FISHERY
Fulvio GARIBALDI
University of Genoa, DIP.TE.RIS.,
C.so Europa 26, 16132 Genoa, Italy. E-mail: garibaldi.f@libero.it
Abstract
This paper is a review of the literature data on species caught as by-catch in the Italian
pelagic fishery, mainly targeting the swordfish (Xiphias gladius), the bluefin (Thunnus
thynnus) and the albacore (Thunnus alalunga). A significant pelagic shark by-catch is
recorded only for 5 species, such as Prionace glauca, Isurus oxyrinchus, Alopias
vulpinus, Lamna nasus, Galeorhinus galeus and Pteroplatytrigon violacea, but CPUE
values are generally very low, also if compared to some areas of the adjacent Atlantic
Ocean. There are few, scattered data sets available in literature and the majority of them
are referred to the most abundant shark, Prionace glauca. The lack of information about
biology, populations dynamics and migratory routes of pelagic species in the
Mediterranean Sea is pointed out and discussed.
Key words: Pelagic fisheries, by-catch, sharks, Mediterranean.
Introduction
In Italian waters, as in the most part of the Mediterranean Sea, cartilaginous fish are a
relevant by-catch of the professional pelagic fisheries. The traditional harpoon fishery in
the Southern Tyrrhenian Sea and purse seine fishery targeting bluefin tuna show a really
low shark by-catch, generally reduced to a few large specimens.
Fishing activities strictly related to pelagic cartilaginous species are:
1) Surface longline: it is probably the most common fishing gear targeting
swordfish, tunas and other tuna like fish. In the Italian seas more than 1.000 fishing
vessels are using this gear, but many of them are small multipurpose boats, operating at
a small scale. Moreover, there are many different long line types: swordfish longline
(SWO LL), American Type SWO LL, Bluefin tuna longline (BFT LL), Albacore
longline (ALB LL), with different characteristics (nylon thickness, hook number and
size, bait, etc) in order to be the most selective for each target species. Thus, it is really
hard to standardize collect valuable data on the real and the real fishing effort.
2) Driftnets are officially banned from the E.U. countries from 2002, but in
different ways they are still operating, in Southern Italian seas and in the South-West
Mediterranean. At the moment it is not possible to have an estimate of the fishing effort
169
3) (total length of the nets and number of boats operating every night at sea), even
if it is reduced in comparison with the last decade.
No pelagic fishery directly targeting shark exists in Italy and, except restricted
areas, in the whole Mediterranean Sea.
Materials and Methods
Since the 80’s, research programs on pelagic fishery have been carried out in Italy,
funded by the Italian Ministry for the Agricultural Policy,and from EU: aim of these
programs is a better understanding of the biology and population dynamics of the large
pelagic species, mainly swordfish, albacore and bluefin tuna, for stock assessment and
management. Italian seas were divided on the basis of different O.U., similar in
extension to FAO’s GSA, in order to have a complete coverage of the Italian coastline
and ports. These programs are generally carried out monitoring catches at landings. This
is a great difference with programs addressed to the study of demersal resources (cfr.
MEDITS and GRUND programs), based on fishing surveys at sea. This is due to the
fact that for pelagic fishery, fishing surveys at sea are more time and money expensive.
In the framework of these programs, every year a part of the work was carried out by
observers directly on board for each O.U., considering that the only way to collect
biological samples (gonads, stomach contents, etc) because fish are gutted and dressed
for the market at sea. Obviously all possible data on by-catch species, including sharks,
were also collected.
Qualitative information about the presence of species come also from
recreational fishing activities, but they are generally spotted records of occasional
catches.
At present, some new programs funded by Italian Ministry and coordinated by
SIBM (Italian Marine Biology Society) are going to start: they could be very useful
tools considering that they it must be carried out with observers at sea.
Results
A significant shark by catch is recorded only for the 5 following species, as pointed out
by many authors: Prionace glauca, Isurus oxyrinchus, Alopias vulpinus, Lamna nasus,
Galeorhinus galeus, Pteroplatytrigon violacea. All but pelagic stingrays have a good
commercial value. Many other cartilaginous fish are caught, including some protected
(i.e. Mobula mobular and Cetorhinus maximus) or deepwater species (i.e. Hexanchus
griseus), but numbers are generally low. Uncertainty remains about the real incidence
on other pelagic sharks, also considering that for some families (i.e. Lamnidae,
Sphyrnidae and Carcharhinidae) the correct species identification is sometimes very
difficult.
Catch per unit of effort (CPUE) in number (number of individuals for 1000
hooks for longlines, and for 1000 m of net for driftnets) and mean weight are valuable
tools trying to analyze trends in sharks abundance. Available literature data on
170
elasmobranch by-catch from the past are summarized in the following tables: data sets
are mainly referred to blue shark, P. glauca, which is the most common shark.
Table 1. Blue shark CPUE (n) and mean weight (kg) values in the Gulf of Taranto Swordfish longline (combined data and modified from DE METRIO et al.,
1984 – FILANTI et al., 1986).
Years
CPUE (N)
Mean weight (kg)
1978
1,53
9,42
1979
1,13
47,4
1980
0,94
30,28
1981
2,25
20,16
1982
1,40
13,81
1983
3,07
12,3
1984
1,12
21
1985
1,17
9,47
Table 2. Blue shark CPUE (n) and mean weight (kg) values in Southern Adriatic Sea Swordfish longline (modified from DE ZIO et al., 1998)
Years
1984
CPUE (N)
0,71
Mean weight (kg) 16,3
1985
0,76
17
1986
1,71
15,9
1987
0,97
11,6
1991
0,89
14,2
1992
2,38
8,4
1993
1,51
10,1
1994
0,55
9,8
1995
1,12
11,8
1996
0,69
11,7
1997
1,13
10,7
1998
1,87
10,8
Table 3. Blue shark CPUE (n) and mean weight (kg) values in the Ligurian Sea –
Swordfish longline (from GARIBALDI and ORSI RELINI, 2000).
Years
CPUE (N)
Mean weight (kg)
1990
0,28
12,08
1991
0,52
16,6
1992
1,09
12,5
1993
0,08
13,3
1994
0,18
9,28
1995
0,65
8,5
1996
0,4
9,6
1997
0,2
10,4
1998
0,12
9,96
CPUE data for other species are rarely available; they are summarized in the
following tables 4, 5 and 6.
Table 4. Shark CPUE in the Gulf of Taranto – Swordfish longline (from FILANTI et
al., 1986)
Species
M. mobular
L. nasus
S. zygaena
A. vulpinus
H. griseus
1978
0,067
0,220
0,043
0,096
-
1979
0,040
0,184
0,044
0,047
0,004
1980
0,009
0,218
0,007
0,021
-
1981
0,016
0,016
0,004
-
171
1982
0,007
0,013
0,007
-
1983
0,009
-
1984
0,03
-
1985
0,003
0,003
Table 5. CPUE values for other sharks caught in Ligurian Sea - Swordfish longline
(modified from ORSI RELINI et al., 1999; GARIBALDI and ORSI RELINI,
2000).
Species
A. vulpinus
I. oxyrinchus
C. plumbeus
L. nasus
1990
0,047
-
1991
0,013
0,013
-
1992
0,022
-
1993
0,012
1994
-
1995
-
1996
0,009
0,018
1997
-
1998
0,007
0,065
-
-
-
-
-
0,007
Table 6. CPUE values for elasmobranchii - Driftnet (from DI NATALE et al., 1998)
S p e c ie s
P . g la u c a
A . v u lp in u s
I. o x y rin c h u s
S . zy g a e n a
C . m a x im u s
P . v io la c e a
M . m o b u la r
L ig u r ia n S e a
0 ,0 0 9
0 ,0 0 5
0 ,0 0 1
0 ,0 2 2
0 ,0 0 5
T y r r h e n ia n S e a a n d S ic ily S tr a its
0 ,3 5 8
0 ,0 5 1
0 ,6 9 1
0 ,6 9 1
-
At a Mediterranean scale, recent researches were carried out by
BUENCUERPO et al. (1998), on the Spanish fleet harvesting sharks in the Eastern
Atlantic Ocean and Gibraltar Strait, and by TUDELA et al. (2003), on the Moroccan
driftnet fishery in the Alboran Sea. These two studies covered a limited time period
(only one year of observations): results are summarized in tables 7 and 8 respectively.
Table 7. CPUE (n) of sharks caught in the Eastern Atlantic and Gibraltar Strait
(modified from BUENCUERPO et al., 1998).
SWOLL
Sectors
1
2
Eastern Atlantic
3
4
Gibraltar Strait
5
DN
Gibraltar Strait
5
P. glauca
6,17
14,53
30,69
33,69
21,98
I. oxyrinchus
3,03
3,09
4,78
3,9
1,94
A. vulpinus
0,013
0,002
0,015
0,032
0,007
A. superciliosus
0,09
0,5
0,22
0,15
0,02
S. zygaena
0,62
0,07
0,85
0,03
0,28
Total sharks
9,92
18,19
36,55
37,8
24,23
0,32
0,54
0,05
0,22
0,08
1,22
172
Table 8. Estimated CPUE (n) of the Moroccan driftnet fishery in Alboran Sea (from
TUDELA et al., 2003)
C P U E
P . g la u c a
0 ,1 1 7 -0 ,1 2 1
I. o x y r in c h u s
0 ,0 5 9 - 0 ,1 4 5
A . v u lp in u s
0 ,0 9 2 - 0 ,1 1 7
The only program specifically dedicated to monitoring shark by-catch in
pelagic fishery (Project funded by EC 97/50 DG XIV C1) was carried out in Greece,
Southern Italy and Spain during 1998 and 1999 fishing seasons. Main results of this
survey are reported in MEGALOFONOU et al. (2005): CPUE values in number for
swordfish long line are here summarized in Table 10. As authors pointed out, the
highest shark by-catch was found in the Alboran Sea, confirming results obtained by
Buencuerpo et al., 1998.
Table 9. CPUE (n) in different Mediterranean areas – Swordfish longline (from
MEGALOFONOU et al., 2005)
Area
Ionian
Levantine
Adriatic
Tyrrhenian
Straits of Sicily
Balearic
Alboran
Catalonian
Total
P. glauca
0,53
0
1
0,27
0,06
0,07
3,59
0,17
1,24
I. oxyrinchus
0,04
0,19
0,004
0,05
A. vulpinus
0,001
0,004
0,02
0,01
0,008
0,004
0,006
G. galeus
0,14
0,02
0,003
0,007
0,004
0,003
Other species
0,003
0,11
0,001
0,004
0,004
0,002
Discussion
In Italian Seas and throughout the whole Mediterranean, shark by-catches are generally
low if compared with those obtained in the adjacent Atlantic waters (BUENCUERPO et
al., 1998; MEJUTO et al., 2002; MEGALOFONOU et al., 2005). Swordfish longline
present the highest number of by-catches, but, except in the Alboran Sea, percentage of
sharks caught in relation to the target species is very low.
Everywhere CPUE values show a great variability, depending on species, year,
gear and fishing areas, but there is not a definite and clear trend. Data on cartilaginous
fish by-catch are heterogeneous and in most cases not strictly related to a valuable
measure of fishing effort, so standardization is quite impossible; in many cases data sets
derive from restricted geographical subareas, covering a limited time period. Thus there
is a general lack of information about catches, distribution, biology and consistence of
Mediterranean elasmobranch populations. This is mainly due to the small number of
173
research programs specifically targeted to large pelagic fishery by-catch and
consequently to the scarcity of comparable scientific data. There is a need of long-term
monitoring programs, mainly carried out by the means of on board observers, avoiding
the possible bias due to specimens discarded at sea, especially those of protected or no
commercial species (M. mobular, C. maximus, P. violacea). Analysis of published
historical time series shows a generalized decline of the Mediterranean sharks; the mean
size of blue shark is dramatically dropping from the ’80; for the other species, catches
are so low and scattered that it is impossible to establish a clear trend, but it seems that
for all the species the majority of specimens caught are immature. In large pelagic bony
fish, mainly swordfish and bluefin tuna, there is so far many studies on population
structure, age, growth, reproduction, spawning areas etc., which are the starting point
for a correct stock assessment and management.
The same requirements are also needed for cartilaginous fish, but the fragmentation
(temporal and spatial) of available data sets makes the stock assessment in the
Mediterranean really hard.. Some important questions remain unsolved: what is the
meaning of the variations in CPUE values and size of sharks depending on year, season
and fishing areas? Are the Mediterranean shark populations isolated from the Atlantic
ones? Does the Gibraltar Strait represent a phylogeographic break? So far we ignore the
migratory routes and the eventual mixing ratio between Mediterranean and Atlantic
populations of sharks or nursery areas. Considering the high swimming potential of the
individuals, in the case of these highly migratory species we have to proceed with great
caution in the identification of critical habitats.
Finally, considering the high survival rates recorded for sharks caught with
longlines (MEGALOFONOU et al., 2005; pers. observations), it could be possible to
mitigate the impact of these fishing gears releasing live sharks at sea.
References
BUENCUERPO, V., S. RIOS, MORÓN, J., 1998. Pelagic sharks associated with the
swordfish, Xiphias gladius, fishery in the eastern North Atlantic Ocean and the Strait
of Gibraltar. Fish. Bull. 96, 667-685.
DE METRIO, G., PETROSINO, G., MONTANARO, C., MATARRESE, A., LENTI,
M., CECERE, E., 1984. Survey on summer-autumn population of Prionace glauca L.
(PISCES, CHONDRICTHYES) during the four-year period 1978−81 and its
incidence on swordfish (Xiphias gladius L.) and albacore (Thunnus alalunga (Bonn))
fishing. Oebalia 10, 105-116.
DE ZIO, V., PASTORELLI, A. M., ROSITANI, L., 2000. Catture accessorie di
Prionace glauca (L .) durante la pesca dei grandi pelagici nel basso Adriatico (19841998). Biol. Mar. Medit. 7, 444-446.
DI NATALE, A., 1998. By-catch of shark species in surface gear used by the Italian
fleet for large pelagic species. ICCAT Col. Vol. Sci. Pap. 48, 138−140.
FILANTI, T., MEGALOFONOU, P., PETROSINO, G., DE METRIO, G., 1986.
Incidenza dei Selaci nella pesca del Pesce Spada con long line nel golfo di Taranto.
Nova Thalassia 8, 667-669.
174
GARIBALDI, F., ORSI RELINI, L., 2000. Abbondanza estiva, taglie e nicchia
alimentare della verdesca Prionace glauca nel Santuario dei Cetacei. Biol. Mar.
Medit. 7(1), 324-333.
MEGALOFONOU, P., YANNOPOULOS, C., DAMALAS, D., DE METRIO, G.,
DEFLORIO, M., DE LA SERNA, J. M., MACIAS D., 2005. Incidental catch and
estimated discards of pelagic sharks from the swordfish and tuna fisheries in the
Mediterranean Sea. Fish. Bull. 103, 620–634 .
MEJUTO, J., GARCIA-CORTES, B., DE LA SERNA, J.M. 2002. Preliminary
scientific estimations of by-catch landed by the Spanish surface long line fleet in 1999
in the Atlantic Ocean and Mediterranean Sea. ICCAT Col. Vol. Sci. Pap. 54, 11501163.
ORSİ RELINI, L., PALANDRI, G., GARIBALDI, F., CIMA, C., 1999. Long line
swordfish fishery in the Ligurian Sea: eight years of observation on target and by
catch species. ICCAT Col. Vol. Sci. Pap. 49, 146−150.
TUDELA, S., GUGLIELMI, P., EL ANDALOSSI, M., KAI KAI, A., MAYNOU, F.,
2003. Biodiversity impact of the Moroccan driftnet fleet operating in the Alboran Sea
(SW Mediterranean). A case study of the harmful effects inflicted by current IUU
large-scale driftnet fleets in the Mediterranean on protected and vulnerable species.
WWF Mediterranean Programme Office, Rome. VI + 78 pp.
175
Proc. of the Int. Workshop on Med. Cartilaginous Fish with Emphasis on South.- East. Med., 14-16 Oct. 06, Istanbul-Turkey
SHARK RESEARCH PROGRAMME IN LIBYA
Bernard SERET1 and Abdallah BEN ABDALLAH2
1
Muséum National d’Histoire Naturelle, Département Systématique et Evolution, UMS 602 « Taxonomie et
Collections », Case postale n° 26, 43 rue Cuvier, 75231 Paris cedex 05, France. E-mail: seret@mnhn.fr
2
Marine Biology Research Center (MBRC), P.O. Box 30830, Tajura/ Tripoli, Libya
Cartilaginous fishes have traditionally been consumed in Libya, mainly sharks,
guitarfishes and some stingrays. However, very little is known about the Libyan
cartilaginous fishes, and no particular study has been so far dedicated to these fishes.
Also there is no quantitative fisheries data on the landings and catches of these fishes
although they constitute important resources within Libyan fisheries. Because of these
lacks, the Marine Biology Research Centre of Tripoli (MBRC) and the Environment
General Authority of Libya (EGA) were willing to jointly undertake a research
programme on the cartilaginous fishes of Libya. In this context, the Regional Centre for
Specially Protected Areas in Tunis (RAC-SPA) supported an expertise mission in June
2005, in order to consider the conditions of the feasibility of such a study and to
determine the content of an adapted research programme to be jointly carried out by
MBRC and EGA. As a result of this expertise, a research programme on cartilaginous
fishes of Libya has been proposed. It includes three parts: a systematic inventory of the
chondrichthyan fishes of Libya, the biological study of some selected species and the
record of fishery data. The programme should provide the basic information and data
necessary to manage the shark and ray fisheries and to possibly monitor the
conservation of some of their populations or species. The conditions to launch such a
research programme in Libya are quite propitious because of the relatively high
biodiversity of these fishes in Libyan waters and the apparently “good health” of their
populations; also, the human and logistic capacities of both MBRC and RGA would
contribute to the achievement of this programme, which should start in Spring 2005 for
a period of two years. This programme could be considered as a pilot study in the frame
of the implementation of the « Action Plan for the conservation of the cartilaginous
fishes in the Mediterranean Sea » as defined by RAC –SPA in 2002.
176
Proc. of the Int. Workshop on Med. Cartilaginous Fish with Emphasis on South.- East. Med., 14-16 Oct. 06, Istanbul-Turkey
CONSERVATION MANAGEMENT OF SHARKS AND RAYS
(VERTEBRATA: CHONDRICHTHYES) IN THE MALTESE ISLANDS
(CENTRAL MEDITERRANEAN) –
A REVIEW OF STATUS AND TRENDS
Titian SCHEMBRI
University of Malta, Malta
Introduction
Although research on chondrichthyan fishes in the Mediterranean is sparse, enough
information exists to suggest that most grow, mature and recruit very slowly when
compared to the more commercially important groups of teleost fishes. This implies that
chondrichthyans have a low resilience and are therefore more vulnerable to exploitation
than most commercial fish species. Added to this, many species, especially sharks, are
top predators and thus normally have low numerical abundances. Thus shark
populations need careful monitoring to ensure that they survive the impact of human
exploitation.
Located centrally in the Mediterranean Sea, close to the boundary between the
western and eastern basins, the Maltese Islands afford a well placed sampling point for
the region’s ichthyofauna. From as early as the 18th Century, naturalists, fishers and
enthusiasts have compiled lists of the fish fauna of the Maltese Islands (SCHEMBRI et
al., 2003). Unfortunately, while research on chondrichthyan biodiversity has improved
our knowledge on which species are present in the Central Mediterranean, much
remains to be discovered about population dynamics.
Biodiversity Studies
In a recent scientific review of records of sharks and rays from the Maltese
Islands, SCHEMBRI et al. (2003) stressed the need for compiling an accurate inventory
of the species that occur in a given region as the basis for the implementation of
management initiatives, including conservation and food production. Most publications
that mention the chondrichthyans of the Maltese Islands, however, are general
descriptive accounts of Maltese fisheries, or reports on the economic status of these
fisheries issued by the Maltese authorities or are of a primarily cultural nature; others,
while more scientific, included outdated records that had not been substantiated by live
specimens.
In order to address this problem, a long-term study of the fish fauna of the
Maltese Islands was carried out in which the evaluation of previous records was sought
by examining and accurately identifying specimens caught by fishers or seen by the
authors, and those kept in museum collections. Photographs of caught specimens but
which were not preserved were also considered. Out of 37 species of sharks and 26
species of rays previously recorded from Malta, 26 sharks and 14 rays were
authenticated (SCHEMBRI et al., 2003). Other records have yet to be validated.
177
Confirming certain species (for example, Centrophorus uyato) proved elusive
mainly because these sharks are also caught from northwest of the Sicilian channel and
thus specimens landed in Malta may originate from outside Maltese waters. Records of
species such as the Basking shark (Cetorhinus maximus), while obviously valid, may be
outdated as this species has not been observed in or around local waters since 1928
(DESPOTT, 1930).
What is certain is that determining the status of chondrichthyans from fisheries
landings data is not always possible as data on individual species is not available in
some cases.
Data Collection
Since to date no census has been carried out to determine the status of local
chondrichthyan populations, data from Maltese waters depends entirely on the landing
records collected by the Government’s fisheries agency and the trends emerging from
such data over several years. While the accuracy of the landing records collected has
improved greatly over the past few years, these records are not yet reliable enough to be
used as an accurate estimate of the status of local populations. Some of the current
major problems are:
• Non-commercial species, and those species which inhabit regions not exploited
by fishers, are not landed. Thus, referring to a particular species as “rare” simply
because it is seldom landed is often misleading.
• Not all the species landed are recorded through the official channels. Some are
sold or cut up before landing, others are thrown away2.
• Some closely related species are lumped together in the official records, making
it difficult to collect data on a particular species and/or populations.
• Trends showing an increase or decrease in landings do not always reflect a
similar change in the overall population, as landings depend on a number of
factors other than population abundance, namely the fishing effort, the
commercial value of the species and market considerations (which are subject to
variation) and the fishing gear/methodology (which may also vary with time).
Maltese Fisheries
Fishing in the Maltese Islands is mainly centred upon coastal or small-scale
fisheries, which are largely seasonal. Several species of chondrichthyans are either
landed as by-catch during the seasons involving the highly commercial landings or are
targeted in their own right. The Bluefin tuna, Thunnus thynnus thynnus (May and July),
and the Dolphin fish, Coryphaena hippurus (September to December), seasons are the
most commercially important for the Maltese market, both because of the amount of
fish caught and for the income generated by the catch. Other seasons that are less
important but still provide a significant contribution to the catch and income include the
2
An example of this is the Bigeye thresher shark (Alopias superciliosus). Since the
flesh of this species is unmarketable, fishers are fined if it is present in their catch. It is
thus thrown back if caught and there are no landing data for this species.
178
demersal species season (January to April), the Lampara season (March to July) and the
Swordfish, Xiphias gladius, season (September to November; SCHEMBRI et al., 1999)
The most widely used gear includes long-lines, which involves unravelling a
long line of baited hooks. These are set adrift for pelagic species and close to the bottom
for demersal species (SCHEMBRI et al., 1999). This technique is mainly used for
Bluefin tuna and Swordfish, while a deep-sea version (with the line just a few meters off
the seabed) is used for species collectively termed ‘Dogfish’ (Hexanchidae, Squalidae,
Scyliorhinidae and Triakidae), Stone bass, Grouper and Snappers (the larger species of
Serranidae) and other demersal species. The larger boats that venture beyond 25
nautical miles and remain at sea for at least 5 days may set as many as 2000 hooks at
any time, weather permitting. Smaller craft spend a maximum of three days at sea and
set between 500 and 700 hooks per effort (SCHEMBRI et al., 1999). During the Bluefin
tuna and Swordfish season, large pelagic sharks are occasionally landed as by-catch.
These generally include Mako sharks (Isurus oxyrinchus), Porbeagle sharks (Lamna
nasus), Thresher sharks (Alopias vulpinus) and Blue sharks (Prionace glauca). A
stronger version of the pelagic long-line is used specifically for large sharks such as
Blue sharks (P. glauca), Thresher sharks (A. vulpinus), Requiem sharks
(Carcharhinidae) and Mako sharks (I. oxyrinchus).
The ‘Kannizzati’ (used mainly for Dolphin fish) and ‘Lampara’ methods both
involve encircling a given area where fish accumulate with nets, but the size of mesh
and the materials used differ. Floating ‘Fish Aggregating Devices’, or FADs, are used to
attract Dolphin fish as these fish seek shade. The Lampara method, which derives its
name from the bright lamp used to attract mainly Bogue (Boops boops) and Mackerel
(Trachurus spp., is not now much in use, mainly because other, more economical
methods proved as effective. Sharks are seldom landed by the Lampara method.
Bottom trawling takes place in the winter months. Shallow coastal waters are
trawled for demersal species in autumn/winter. Several species of rays and a number of
the smaller ‘dogfish’ species (Squalidae, Scyliorhinidae) may be landed with this
method.
Drift nets are used during May to August for specific pelagic species. Pelagic
sharks are sometimes caught as by-catch.
Recent Trends In Fisheries Landings
Data on fish catches are compiled by the Government’s fisheries agency, which
at present is known as the Department of Fisheries and Aquaculture. Statistical data on
fish landings are collected through the Wholesale Fishmarket in Valletta. The data
presented in figures 1 and 2 only cover landings in Malta as there is still, to date, no
equivalent market in the sister island of Gozo. Furthermore, a part of the catch is not
recorded for various reasons that are beyond the control of the Department of Fisheries
and Aquaculture (SCHEMBRI et al., 2002). It is assumed that at least 25% of all
catches goes unrecorded.
Figures 1 and 2 show the trends for all cartilaginous species as given in the
Malta State of the Environment Report 2002 (SCHEMBRI et al., 2002). The different
species landed under the general category ‘dogfish’ include several species of the
179
families Scyliorhinidae, Squalidae and Triakidae. Since data for separate species is not
available, they are shown here as one group. Rays and skates are also grouped together.
Torpedo rays (Torpedo spp.), Long-nosed skates (Dipturus oxyrinchus) and small rays
(Raja spp.) are fairly common on the market, the most common by far being members
of the family Rajidae (of which the main species landed are D. oxyrinchus, Raja
asterias, Raja miraletus, Raja montagui, and Raja radula).
Figure 1. Annual landings for sharks and rays.
Figure 2. Percentage composition of catch for sharks and rays.
From Figures 1 and 2 the following trends are evident:
Angelsharks (Squatina spp.) disappeared from the records for a number of
years. However, this does not mean that they were not caught. The amount landed
180
yearly decreased to the point where records were grouped with those of other species,
and were not reported separately. Whether this decline is due to a change in fishery
practice or whether it reflects a change in abundance is not known but fishers comment
that Angelsharks are not as common as they used to be (Various fishers in personal
communication with the authors).
There is a slight increase in the catches of Blue Shark (Prionace glauca) but a
decrease in those of the ‘dogfish’ species. Whether this is a reflection of changes in
abundance or a decrease in fishing effort remains to be seen.
A slight increase in Porbeagle sharks (I. oxyrinchus, L. nasus, Carcharondon
carcharias) in 1997 is countered by a severe dip in 1998.
Rough shark (Oxynotus centrina, Centrophorus granulosus, C. uyato) catches
have also decreased while no recent data are available for the Six- and Seven-gilled
sharks; since 1997, these species were merged with those in the ‘Dogfish’ or ‘Other
fish’ categories.
The weight (in kg) of sharks and rays passing through the Valletta Wholesale
Fishmarket for the period 1996-2001 are given in figures 3 to 7.
8,000
7,000
6,000
5,000
kg 4,000
3,000
2,000
1,000
0
1996
1997
1998
1999
Year
2000
2001
2002
Figure 3. Annual landings for rays and skates.
Rays and Skates (Figure 3) – The graph shows a slight decline between 1996
and 2002. Rays and skates are landed throughout the year, but more commonly during
the demersal season (i.e. January to April) and during spells of bad weather, when
fishing is carried out closer to shore and bottom long lines are used. The most common
species caught include members of the genera Torpedo and Raja.
181
30,000
25,000
20,000
kg 15,000
10,000
5,000
0
1996
1997
1998
1999
year
2000
2001
2002
Figure 4. Annual landings for dogfish.
Dogfish (Figure 4) – The graph shows a decline from 1996 to 2001, followed
by a slight increase in catch in 2002. Like the rays and skates, dogfish are landed mainly
during the demersal season, but may be encountered in smaller numbers throughout the
year. During the last few years the Six-gilled and Seven-gilled sharks (Hexanchus
griseus and Heptranchias perlo, respectively) were included in this category, which
explains their disappearance from the records after 1997 (Figures 1, 2).
5,000
4,500
4,000
3,500
3,000
kg 2,500
2,000
1,500
1,000
500
0
1996
1997
1998
1999
year
2000
2001
Figure 5. Annual landings for Rough shark.
182
2002
2,500
2,000
1,500
kg
1,000
500
0
1996
1997
1998
1999
year
2000
2001
2002
Figure 6. Annual landings for Blue shark.
Roughshark (Figure 5) – This graph shows a general decline between 1996 and
2002. “Roughshark” generally refers to Gulper sharks (Centrophorus granulosus and C.
uyato), although occasional landings of other species of deep sea Squalidae and the
Angular rough shark (Oxynotus centrina) may also be included.
Blue shark (Figure 6) – It is interesting to note the decreasing trend in Blue
Shark landings after 1997, although the reason behind this decline remains to be
ascertained.
7,000
6,000
5,000
4,000
kg
3,000
2,000
1,000
0
1996
1997
1998
1999
year
2000
2001
Figure 7. Annual landings for Rough shark.
183
2002
Roughshark (Figure 7) – It is not clear whether this category includes all the
species of the Lamnidae, or whether only the Mako shark (I. oxyrinchus) is caught in
amounts significant enough to appear in the statistical reports3. A general decrease is
also present in this category after 1997 (Figure 7), but the reasons for this are not yet
known. Fishers comment that Makos (I. oxyrinchus) and Porbeagles (L. nasus), which
share the Maltese vernacular “Pixxiplamtu” and are thus reported collectively under this
name, decreased considerably (to the point of becoming scarce) in the last 20 years
(Fishers, pers.comm.).
Current Legislation
Before the 1990s, national legislation concerning the protection and
conservation of flora and fauna was rather limited in Malta (SCHEMBRI et al., 2002).
A new Environment Protection Act (Act XX of 2001) was published on the
18th September 2001 (Chapter 435 of the Laws of Malta). This Act is essentially a
framework law with various mandatory provisions granting the Minister responsible for
the environment the possibility of issuing subsidiary legislation on various issues related
to, amongst others, the protection of biological diversity, integrated pollution prevention
and control, waste management, genetically-modified organisms and environmental
audits. Many of the provisions at the time were novel issues in Maltese Law, and were
first introduced into national legislation through this new act (SCHEMBRI et al., 2002).
Legal Notice 257 of 2003 published under the Environment Protection Act
issued a set of regulations called the Flora, Fauna and Natural Habitats Protection
Regulations. C. carcharias, C. maximus and Mobula mobular are listed under Schedule
V of these Regulations, which means that they are protected in Maltese waters and may
not be disturbed or harmed in any way. Another 11 sharks and 3 rays are listed under
Schedule VI, which lists those species whose exploitation may be subject to regulatory
measures to ensure a favourable conservation status. Such measures include temporary
prohibition of capture, regulation of fishing seasons and fishing methods, regulation of
licences and landings quotas, and any other method deemed necessary. Table 1 lists a
number of species that fall under Schedules IV and V of these regulations.
3
For example, several members of the Carcharhinidae (Carcharhinus brevipinna, C.
obscurus, C. limbatus) and the Thresher shark (Alopias vulpinus) are certainly landed
(Fishers, pers. com.), but do not appear anywhere in the statistics. Up to the time of
writing, the author could not ascertain whether they are recorded under other names or
simply not included, perhaps because the figures are too low.
184
Table 1. Shark and ray species listed under the Flora, Fauna and Natural Habitats Protection
Regulations
Scientific name
Schedule V
Vernacular name (Malt.)
Vernacular name (Eng.)
Carcharodon carcharias
Kelb il-Bahar
Great White Shark
Cetorhinus maximus
Pixxitonnu
Basking Shark
Mobula mobular
Baqra; Manta; Raja tal-Qrun
Devil Ray
Schedule VI
Alopias vulpinus
Pixxivolpi
Thresher Shark
Carcharias Taurus
Tawru
Sandtiger Shark
Carcharhinus brevipinna
Kelb il-Bahar
Spinner Shark
Carcharhinus limbatus
Kelb il-Bahar
Blacktip Shark
Carcharhinus plumbeus
Kelb griz
Sandbar Shark
Galeorhinus galeus
Kelb il-Bahar
Tope Shark
Hexanchus griseus
Murruna ta' Sitt Gargi
Bluntnose Sixgill Shark
Isurus oxyrinchus
Pixxitondu
Shortfin Mako Shark
Lamna nasus
Pixxiplamtu
Porbeagle Shark
Prionace glauca
Huta Kahla
Blue Shark
Pristis pristis
Pixxisega; Pixxiserrieq; Sija
Common Sawfish
Rostroraja alba
Raja
White Skate
Leucoraja melitensis
Raja ta' Malta
Maltese Brown Ray
Squatina squatina
Xkatlu
Angel Shark
The Fisheries Conservation and Management Act (Act II of 2001), which
replaced the Fish Industry Act (Act XII of 1953 as amended, Chapter 138 of the Laws
of Malta), relates to the conservation, assessment and management of fish stocks, where
‘fish’ means “any aquatic animal, whether piscine or not, and includes shellfish,
crustaceans, sponges, sea urchins, turtles, aquatic mammals and their young, fry, eggs or
spawn and shells and parts thereof and fish meal”.
By virtue of Article 38 of this Act, the Minister responsible for fisheries may
make regulations, on, amongst others, the conservation, management and protection of
fish resources including the establishment of closed areas and closed seasons, the
establishment and management of marine areas for the preservation of fish stocks,
including their means of sustenance; the control of the exploitation of coral and sponge
resources, and the protection of turtles, dolphins “and other aquatic animals”. These
provisions overlap considerably with those of the Environment Protection Act.
Current Initiatives
Species Action Plan Programme
This programme, initiated by the Malta Environment and Planning Authority in
1998, involves specific management plans for the protection of endangered species and
their habitats and eradication control plans for invasive alien species. This programme is
185
being implemented in phases. Currently, the identification of endangered species
requiring special conservation measures for their long-term survival is being carried out
(SCHEMBRI et al., 2002).
In 2003 a call for tenders for a National Biodiversity Database was issued by
the Malta Environment and Planning Authority. Included among these was a call for a
Biodiversity Database on fish, including chondrichthyans. This database is still under
construction and should be complete by the end of 2006. The database will serve as a
tool for identifying species in critical conservation status and as a reference tool for
future research projects with conservation as their main aim.
Discussion
Although strategies for the conservation of a number of named species can be drafted
and may eventually be implemented, ascertaining whether such strategies are having a
significant effect on the status of a population or not, requires close monitoring. The
conservation status of local populations of chondrichthyans is currently unknown, for
the various reasons given above. Therefore the next step towards implementing
measures to improve their conservation status around the Maltese Islands should be to
carry out pilot surveys to identify which populations are in critical need of conservation
management.
These surveys should be carried out while keeping disturbance levels to an
acceptable minimum level. Once the factors having a detrimental effect on the
populations are identified, realistic methods (such as regulations, landings quotas, etc.)
for improving local stocks can be implemented. Other data to be collected include
identification of nursery areas, chances of survival after release, and distribution.
Direct observation, tagging, capture-recapture, photographic recording, and
interviews with local fishers and divers are all useful tools for collecting data about
local chondrichthyan populations. Fishers should also be instructed on the detrimental
effect of certain practices to help them understand why certain measures are necessary
and to ensure their cooperation. Adequate compensation, should the release of certain
species caught have an impact on the profit margin of local fishers, can only be
negotiated and agreed through open dialogue between the parties involved. Volunteers
(for example from local NGOs and divers’ clubs) must also be trained in species
identification. This can be achieved through short courses involving theory and practical
exercises and/or field identification guide books.
Data collected through these means can then be used to augment the alreadyexisting databases and to promote further research projects and implement legislation
and regulations to improve local stocks.
Conclusion
It is evident that at present, data collected by the Fisheries Department, while
sufficiently detailed as the basis for the statistical information published annually by the
National Statistics Office, is not reliable enough to be used as a quantitative indicator of
186
shark and ray population trends. Albeit in recent years a reorganisation of the system
used to collect landings data has improved matters, many distantly related species are
still lumped together. Also, some species belonging to the same family are recorded
under the same vernacular name, thus limiting the use of landings data for population
assessment.
Although a number of alarming trends emerge when the annually collected
fisheries landings statistics are examined, most notably the decline in Blue shark,
Hammerhead shark and Porbeagle shark landings, it is still not fully clear whether the
population status of these species is in danger of becoming critical or not. Certainly
fishers have noted a distinct decline in occurrence over the last twenty years and the
trends seem to confirm this.
The extent and nature of the decline in landings must be ascertained as a first
step towards compiling a strategic plan whereby sustainable fishing activities can
continue while the conservation of local populations of sharks and rays remains a
realistic goal. Now that a significant number of shark and ray species have been
confirmed for the Maltese Islands (SCHEMBRI et al., 2003), a quantitative study of the
populations of these species is due.
References
DESPOTT, G., 1930. Ichthyological and carcinological notes. Archivium Melitense
8(2), 42-48.
SCHEMBRI, P. J., BALDACCHINO, A. E., CAMILLERI, A., MALLIA, A., RIZZO,
Y., SCHEMBRI, T., STEVENS, D. T., TANTI, C. M., 1999. State of the
environment report for Malta 1998: Living resources, fisheries and agriculture, pp
109-283. In: State of the environment report for Malta 1998. Floriana, Malta:
Environment Protection Department, Ministry for the Environment, pp 448.
SCHEMBRI, P. J., BALDACCHINO, A. E., MALLIA, A., SCHEMBRI, T., SANT, M.
J., STEVENS, D. T., VELLA, S. J., 2002. State of the environment report for Malta
2002: Living resources, fisheries and agriculture. pp 162-346. In: State of the
environment report for Malta 2002. Santa Venera, Malta: Ministry for Home Affairs
and the Environment; iv + 581 pp.
SCHEMBRI, T., FEGUSSON, I. K., SCHEMBRI, P. J., 2003. Revision of the records
of shark and ray species from the Maltese islands (Chordata: Chondrichthyes) The
Central Mediterranean Naturalist, Malta 4(1), 71-104.
187
Proc. of the Int. Workshop on Med. Cartilaginous Fish with Emphasis on South.- East. Med., 14-16 Oct. 06, Istanbul-Turkey
GENERAL OVERVIEW OF SHARKS LANDING AND RESEARCH
PROGRAMME IN MOROCCO
Amina MOUMNI, Abdelhakim MESFIOUI and Said SEMMOUMY
Institut National de Recherche Halieutique 2, Rue de Tiznit/ Casablanca, Morocco
Abstract
In Morocco, sharks were not targeted due to the fact that their value is not so important.
Nowadays, this fishery has undergone a great change and it gained some importance.
Since 1980, annual catches of sharks in Morocco have increased in spite of the fact that
the landings are generally dominated by-catch. In 2000, the catches were 3400 tons.
Over 30 species are identified along Moroccan coasts. The important catches are
realised at the Atlantic coast.
Pelagic sharks are caught primarily as by-catch in the swordfish and tuna
longline fisheries; landings come primarily from a developing directed longline fishery.
Benthic sharks are mostly catch by trawl.
Morocco has understood a shark research programme in 2001 focused on the study of
the biology and ecology of the most dominates species in the capture.
Key words: Landing, assessment, IPOA-Sharks.
Introduction
In Morocco, sharks were not targeted due to the fact that their value is not so important.
Nowadays, this fishery has undergone a great change and it gained some importance
(KIFANI, 1999).
As regards the biology aspects, sharks remain largely under-studied fishes and
their conservation status has not been fully assessed.
Sharks Landings in the Fishing Port
Since 1980, annual catches of sharks in Morocco have increased in spite of the
fact that the landings are generally dominated by-catch. In 2000, the catches were 3400
tons (KIFANI, 1999).
188
4000
Landings (tons)
3500
3000
2500
2000
1500
1000
500
03
02
04
20
20
20
00
99
98
01
20
20
19
19
96
97
19
19
94
95
19
93
19
19
91
90
89
92
19
19
19
19
87
88
19
19
86
85
19
19
83
19
19
84
0
Years
Figure 1. Annual landings of sharks in Morocco from 1983 to 2004 (Statistics ONP).
30000
Values (Dhs)
25000
20000
15000
10000
5000
0
83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04
19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 20 20 20 20 20
Years
Figure 2. Annuals Values of landings in Morocco from 1983 to 2004 (Statistics of
ONP).
The landings at the fishing port are given in figure 3. We can notice that the
important catches are realised at the Atlantic coast. In the contrary, the catches at the
Mediterranean region aren’t very important by comparison to the Atlantic side.
189
AN
N A
A
H DO
O
C R
E
IM
A
M
ar
ti l
M
TA 'DIQ
N
G
E
R
A
S
LA ILA
R H
AC
H
E
M
E
H
D
IA
M
R
O
H AB
C AM A T
A
SA ME
B DI
L
A
E ANC
J O L JA A
R
D
F
I
LA DA
SF
AR
E
SS S A
IM A O F I
ES UI
R
S
O A
U
A
A NE
G
A
S DIR
ID
I
TA IFN
I
N
TA TA
R N
LA FA
AY Y A
B OU
O
U NE
JD
O
D UR
A
KH
LA
R
A
L
A
S
K
E
BD
Mean weight (tons)
450
400
350
300
250
200
150
100
50
0
Ports
Figure 3. Mean weight (Tons) of shark landings in Moroccan fishing ports from the
1983 at 2004 (Statistics of ONP).
RA
S
ES
S
SA AF I
O
IM
U
ES
IR
SO A
U
AN
AG E
AD
IR
SI
DI
IF
T A NI
N
T
T A AN
RF
AY
LA
AY
A
O
BO UN
E
UJ
DO
U
DA R
KH
LA
30
25
20
15
10
5
0
KE
BD
AN
NA A
AL
D
HO OR
CE
IM
A
M
ar
t il
M
'D
TA IQ
NG
ER
AS
IL
LA AH
R
AC
HE
M
EH
D
IA
RA
M
O
HA BA
T
M
CA ME
SA
D
BL IA
AN
CA
EL
JO JA
RF DID
LA A
SF
AR
Price (Kg/Dh)
Moreover, the value of sharks at the fishing ports at the Mediterranean side is
higher than the Atlantic side.
Ports
Figure 4. Mean price (Kg/Dh) of shark landings in Moroccan fishing ports: series 19832004 (Statistics ONP).
Specific composition of shark landings
Over 30 species are identified along Moroccan coasts (KIFANI, 1999) (Table
1).
190
Table 1. Some important species in Moroccan coasts
Scientific names
Common names
Alopias vulpinus (Bonnaterre, 1788)
Carcharhinus altimus (Springer, 1950)
Carcharinus obscurus ( Lesueur,1818)
Cethorhinus maximus (Gunnerus,1765)
Centrophorus granulosus (Bloch and
Schneider,1801)
Centrophorus uyato (Rafinesque,1810)
Centrophorus squamosu (Bonnaterre, 1788)
Daenia calceus (Lowe,1839)
Dalatia lichia (Bonnaterre, 1788)
Galeorhinus galeus (Linnaeus,1758)
Galeus melastomus Rafinesque,1810
Heptranchias perlo (Bonnaterre, 1788)
Hexanchus griseus (Bonnaterre, 1788)
Isurus oxyrinchus Rafinesque, 1810
Mustelus asterias Cloquet, 1821
Mustelus mustelus (Linnaeus,1758)
Prionace glauca ( Linnaeus,1758)
Scyliorhinus canicula (Linnaeus,1758)
Sphyrna zygaena (Linnaeus,1758)
Squalus blainvillei (Risso,1826)
Bigeye thresher
Bignose shark
Dasky shark
Basking shark
Ecological
status
Pelagic
Epipelagic
Benthopelagic
Pelagic
Gulper shark
Benthic
Little gulper shark
Leafscale gulper shark
Birdbeak dogfish
Kitefin shark
Tope shark
Blackmouth catshark
Bluntnose sevengill shark
Bluntnose sixgill shark
Shortfin mako
Starry smoothhound
Smoothhound
Bleue shark
Smallspotted catshark
Smooth hammerhead
Longnose spurdog
Benthic
Benthic
Benthic
Benthic
Benthopelagic
Benthic
Benthic
Benthic
Epipelagic
Benthic
Benthic
Pelagic
Benthic
Pelagic
Benthic
Fishing Gear
Pelagic sharks are caught primarily as by-catch in the swordfish and tuna
longline fisheries; landings come primarily from a developing directed longline fishery.
Benthic sharks are mostly catch by trawl (SROUR, 1986).
In the SW Mediterranean coast of Morocco (Alboran sea), TUDELA et al.
(2005) undertake a study of the large-scale Moroccan driftnet fleet between December
2002 and September 2003; he attest that 498 blue sharks (Prionace glauca), 542
shortfin makos (Isurus oxyrinchus), and 464 thresher sharks (Alopias vulpinus) were
caught during the sampling period, during the peak of the swordfish fishery.
We noted that sharks are mostly targeted by artisanal fisheries using line,
longline and driftnet.
Research Program in Morocco
The International Plan of Action for Conservation and Management (IPASharks) developed by FAO in 1998, engaged countries to elaborate National Plan
191
Action regarding the conservation and Management of the shark populations of Sharks
(FAO, 1998).
In this context, Morocco by The National Institute of Marine Halieutic
Research undertakes a shark research program in 2004, as a diagnostic. This program
will be a basis of elaborates the National Plan Action.
Objectives of the programme
In terms of their biology, sharks remain largely under-studied fishes and their
conservation status has not been fully assessed. In commercial terms, data on shark
landings are mostly mixed with that of skates, rays and chimaeras and grouped in a
rubric “Squalls”. Therefore, the aims of this programme are the following:
•
•
•
The improvement of biological and statistical data;
The evaluation of the exploitable potential of resources;
The estimation of the global impact of this fishery.
Methodological Approach used
There are steps in the process of implementing this program.
The methodological approach consists first on collecting information and data.
It’s based on:
•
•
Sampling in the fishing port and in the vessel research, it consist on doing
the specific composition, collecting biological material
Investigation in the fishing ports: It concerns the fishing area, fleet,
number of trips, bottom, nature of bottom
The second stage of this programme will focus on the study of the biology and
ecology of the most dominates species in the capture.
On the basis of these parameters and statistics, we can estimate the exploitable
potential of this fishery as well as the state of exploitation.
These components are essential for us to be able to elaborate the action plan for the
management of this fishery.
Concerning this step, we started the study at Casablanca fishing port because it
considered as the most important port in term of commercial activity. And then, we will
consider prospecting other ports.
• Mediterranean side: Nador – Tanger
• Atlantic side: Laayoune – Dakhla
References
FAO, 1998. Consultation on the management of fishing capacity, shark fisheries and
incidental catch of seabirds in longline fisheries. FAO Fisheries Report N°: 584.
FIPP/R584. ISSN: 0429-9337.
KIFANI, A., 1999. Exploitation of sharks. Bibliographic report, pp 18.
192
SROUR, A., 1986. Exploitation of sharks. Report ISPM.
TUDELA, S., KAIKAI, A., MAYNOU, F., EL ANDALOUSSI, M., GUGLIELMI, P.,
2005. Drifnet fishing and biodiversity conservation: the case study of the large-scale
Moroccan driftnet fleet operating in the Alboran Sea (SW Mediterranean). Biol.
Conserv. 121, 65-78.
193
Proc. of the Int. Workshop on Med. Cartilaginous Fish with Emphasis on South.- East. Med., 14-16 Oct. 06, Istanbul-Turkey
ESTABLISHING AN INFORMATIVE (SAMPLING) NETWORK FOR
THE ASSESSMENT OF THE STOCK STATUS OF SHARKS:
A REVIEW
David MACÍAS and M. Jósé MELENDEZ
Instituto Español de Oceanografia (IEO), Spain.
The information about trends in the abundance of a determinate species population is
one of the most important issues to assess the species status. Knowing the status and
recent trends in the abundance of a given species is essential to manage and protect such
species.
Planning programs, protocols and sampling forms to collect the information
from the fisheries must be done taking into account the following factors:
• Source of information (Fishery-dependent sampling or fishery-independent
data)
• Data type
• Fishing gear
Sources of Information
1. Fishery-Dependent Sampling
Fishery-dependent data collection is one of the most valuable tools available to
fishery managers.
The management plans based on fishery-dependent sampling will only be as
good as the data collected. It is critical to determine which one is the most important
data to be collected and implement some system of data recording before overfishing
occurs.
From a general point of view five methods are used in the collection of
fisheries and biological data:
1. Fisheries observers
2. Shore and dockside sampling
3. Local fishery authorities data
4. Logbooks
5. Telephone and dockside surveys.
Each one has positive and negative aspects, and the decision to use one or other
usually depends on the size of the vessels, the duration of the fishing trips, the type of
data to be collected, and the fundings available to support the data gathering.
Usually a combination of two or more methods is required for adequate data
gathering.
194
1. 1. Fisheries observers
Fisheries observer programs are used worldwide to collect high quality
fisheries data including:
• biological data
• species composition
• discards
Observers can collect a variety of information, including:
• fishing location and depth
• time of sets and haul back
• oceanographic data (e.g., water temperature and salinity)
• type and amount of gear used
• effort data
• changes in the gear or fishing strategy
• species identification
• catch vitality
• discards quantification
• total catch data (Commercial plus discards)
• sex ratios
• lengths and weights
• maturity and biological samples
• Phothographic matherial
• Fishers awareness about fisheries management requirements
Observers are extremely beneficial to management programs because of the
amount and accuracy of the information they collect. However, observer programs can
be expensive, time consuming, and impractical if the boats in the fishery are too small
(i.e., if they have space problems).
1. 2. Shoreside sampling
Shoreside sampling is very useful in fisheries where sharks are landed whole,
such as recreational and some artisanal fisheries. However, sharks are often dressed at
sea and are landed headed and gutted, which can give rise to significant problems for
land based sampling since species identification, sex, fork and total length, reproductive
sampling, as well as at-vessel vitality cannot be determined.
If sharks are landed intact, then a shore-based data collector can produce many
of the same data as an onboard observer. These data are:
• commercial data
• accurate identification of commercial species
• sex ratios
• lengths and weights
• Maturity data
Additional data, such as fishing location and depth, type of gear used, etc. can
be gathered by interviewing the fishers.
195
1. 3. Data from the local fishery authorities
The local authorities usually gather data about landing of each commercial
species. This information usually consists of temporal series of total fleet landing of
each commercial species.
The main problems of this kind of data are that they:
• Lack of data on discards
• Lack of data on by-catch of non commercial species
• Do not include data about fishing operations, gear and effort
• Errors in the identification of species.
1. 4. Logbooks
Logbooks are used in many fisheries, but data they gather are highly variable.
Despite this, logbooks are commonly used in stock assessments and as the major data
collection source in numerous fisheries. Fishers are required to fill out logbooks while at
sea. The following data can be recorded in logbooks:
• species identification
• number caught
• sex ratios
• size
• disposition
• gear and amount used
• gear modifications
• location
• time of set and haul back
• depth and water temperature
It is widely recognized that fishers do not always record accurate data, as they
under-report their catches, and frequently identify species incorrectly.
1. 5. Telephone and dockside sampling
Telephone or dockside surveys are often used to monitor recreational fishers
and involve either calling or going to the docks and interviewing fishermen about their
trips as they come back in. Surveyors usually ask questions about the species targeted
and catch composition, type and amount of gear employed, gear modifications and
lengths, and size of the vessel. This is a very basic type of data collection and there are
real problems associated with the poor quality of the data.
As in logbook data, this type of data gathering is relatively inexpensive and
provides a reasonable alternative to more expensive methodologies.
2. Fishery-Independent Sampling
Fishery-independent estimates of abundance are the cornerstone of many stock
assessments for teleost and shellfish species. Fishery-independent surveys provide
valuable measures of relative abundance, rates of population change, size and sex
composition for a wide range of species. As these measures are obtained from
196
experimental designs, they are less subject to uncertainty. For a variety of reasons,
fishery-independent surveys for elasmobranchs are more difficult to interpret than
surveys for teleosts.
There are two primary uses of fishery-independent surveys.
1) The first use is to generate an estimate of population abundance. Estimate
relative density can be used to infer trends over time and calibrate numerical population
models, but for this the target population and area must be well defined. Otherwise
inferences are restricted to population available to area sampled.
2) The second use of fishery-independent surveys is to examine attributes of
the sampled population (such as size frequency, maturity, sex ratios and age). These
attributes help us to understand the basic biology of species and to define the developing
life history of models (RAGO et al., 1998).
Derived indicators of abundance are used to calibrate various population
models for teleosts. However, these have less applicability for elasmobranchs for a
number of reasons, as many of the characteristics of their life history can distort the
interpretation of such data.
3. Type of Data
3. 1. Catch estimates
Several key factors are used to determine the status of a fishery. Among these
factors are the catch estimates for both target species and any other bycatch involved in
the fishery. Each individual fishery should maintain a continuous database that includes
all reported catch, estimates of discard, and estimates of non-reported catches.
Catch estimates are used to:
• illustrate the species composition of individual fisheries
• set rates of each captured species
• monitoring quotas
• estimate fishing mortality
• calculate Catch Per Unit Effort (CPUE)
These estimates include all fishes retained or discarded.
Catch estimates allow managers to determine the current status of a fishery and
can also be used to show historical trends in the fishery, and estimate the population
abundance. These numbers can also be integrated into models to predict the outcome of
future management plans or to estimate the effect current management will have on the
stock. At-sea catch estimates often give a very different view of what is actually
happening in a fishery as compared to landings (marketed catch) data. Bycatch is a
common side effect of directed fisheries. Sharks are commonly caught as bycatch in a
number of directed. The catch numbers, mortality, and disposition for all of these sharks
must be recorded in the same manner as that of directed and multi-species fisheries.
3. 2. Fleet inventory
Data about the fleet that operates in a determinate fishing ground is another key
factor affecting the fishery management. These data can be used to estimate the total
effort that is being applied to a given fishing ground (fishing power).
197
This inventory consist of a list of all vessels that operate in this area, gathering
together all the characteristics of each vessel: GRT, HP, Length, Base port, equipment,
fishing gear, etc.
3. 3. Fishing effort (CPUE)
The “effort” usually refers to time spent or to a certain piece of the fishing gear
deployed in the water.
Catch per unit effort (CPUE) is a ratio commonly used to eliminate temporal
and regional trends in fish stock abundance. Many aspects of the fishery can be
monitored using CPUE analysis, including trends in overall fishery catch rates, catch
rates of target vs. bycatch species, etc. CPUE is a much more powerful tool than catch
data alone. A decline in CPUE over a time period is usually a good indication that
stocks are declining. However, changes or improvements in fishing gear, technology or
abilities can influence CPUE trends.
Units of effort are dependent on the type of fishing gear used and can use such
measures as the numbers of vessels, vessel-days, gillnet or longline sets, number of
hook hours, and trawl or gillnet hours.
3. 4. Landings
Landings reports are one part of the process of estimating total catch and also
are used to show how many individuals of each species of shark are brought to port for
distribution or sale. There often is quite a difference between the number of sharks
caught and the number of sharks actually landed. This is a biased assessment of the
actual catch, because many sharks are discarded at sea. A well-designed management
plan will consider both catch and landings data.
•
Problems associated with landings reports
Species identification. A major shortcoming in using landings data is the
common lack of species identification. In many shark fisheries, the sharks
are dressed at sea in order to ensure high quality of the flesh.
• Carcassed landings also eliminate the ability to record the total size or
weight of a shark (sex and reproductive maturity cannot be determined after
the shark has been dressed)
• Quantification of bycatch is also lost using landing data, as it happens with
the information on cryptic mortality (e.g., freshly-caught sharks used as bait
at sea) and vitality (alive or dead) of captured sharks.
3. 5. Fishing mortality
Fishing mortality is a very important but sometimes underreported aspect of
fishery-dependent monitoring. Individual species react differently to being hooked or
ensnared in a net.
The condition, alive or dead, of every shark that is caught, whether targeted or
taken as bycatch, should be recorded.
198
3. 6. Fishing area
Development of preferred fishing areas is dependent upon vessel size and
cruising range, the availability of targeted species and size classes, weather, currents,
and bottom configuration. Recording accurate fishing locations associated with catch
data allows the fishery managers to:
• distinguish geographical variability in catch rates
• denote changes in the activities of the fishing fleet
• determine sub-population differences in life history parameters
• sense significant declines in regional catch rates (that should be
examined carefully because such trends often are indicative of
localized overfishing)
The most specific and preferred way to report fishing location is by recording
the latitude and longitude of every set. Most commercial fishing vessels from developed
nations have GPS or LORAN systems on board.
3. 7. Size
The sizes of all sharks in the catch should be consistently and accurately taken.
This can be an arduous task and may be unrealistic for some fisheries. Such data is
critical because many species of sharks show dramatic population declines when certain
size/age classes are targeted.
Recorded weights of landed sharks are also used to show trends and shifts in
the fishery. (Most fisheries measure the quantity of landed sharks as dressed weight
metric tons (dw mt). Landing tonnages often are used as surrogate indicators of catch
increases and decreases. This can be very misleading if the sizes and numbers of sharks
being caught are not reported as well.
A variety of measurements are taken on sharks. The three most frequently
used measurements are fork, total and precaudal length. When only a single
measurement can be taken, fork length is the choice of most shark biologists because it
provides a consistent measure of body length.
3. 8. Sex
Sexual segregation of sharks based on depth, season, area and sexual maturity
is common in some species. Many fisheries operate at only certain times of the year or
in selected locations and thus may have a propensity to target, intentionally or
unintentionally, a certain sex or maturity stage. Other fisheries target sharks in the same
location at different times of the year, resulting in catches of seasonally different sexual
maturity groups.
The sex of a shark is easily identifiable by the presence of claspers in males
and their absence in females. In addition, the following information should be recorded
whenever possible: for males, clasper size and maturity; and, for females, uterine
condition, average ovum diameter, and the sizes and sexes of embryos.Reproductive
data collection on female sharks is much more time-consuming and time intensive.
199
References
ANDERSON, R.C., 1993. The shark fisheries of the Maldives. Ministry of Fisheries
and Agriculture, Republic of Maldives and FAO, Madras, India.
BONFIL, R. 1997. Status of shark resources in the southern Gulf of Mexico and
Caribbean: implications for management. Fish. Res. 29, 101-117.
BURGESS, G., JOHNS, K., 1999. Commercial shark fishery observer program:
analysis of the large coastal shark fishery-July and August 1998 season in the
southeastern United States, with a review of the 1998 commercial shark fishery in the
region. Final Report to Highly Migratory Species Division, National Marine Fisheries
Service, Silver Spring, Maryland.
CASEY, J. G., 1964. Angler’s guide to sharks of the northwestern United States: Maine
to Chesapeake Bay. U.S. Fish and Wildlife Service, Bureau Sport Fisheries and
Wildlife 179; Circ.
CARLSON, J AND D. LEE. 2000. The directed shark drift gillnet fishery: catch and
bycatch 1998-1999. Report to Sustainable Fisheries Division, National Marine
Fisheries Serivce, Silver Spring, Mary-land.
CASTRO, J., 1983. The sharks of North American waters. Texas A&M University
Press, College Station, TX.
CASTRO, J., 2000A. Guía para la identificación de las especies de tiburones de
importancia comercial del Océano Pacífico. Dirección General de Administración de
Pesquerías, México.
CASTRO, J., 2000B. Guía para la indentificación de las especies de tiburones de
importancia comercial del Golfo de México. Dirección General de Administración de
Pesquerías, México.
CASTRO-AGUIRRE, J. L., PEREZ, H. E., 1996. Listados faunisticos de Mexico VII.
Catálogo Sistemático de las rayas y especies afines de México (Chondrichthyes:
Elasmobranchii:Rajiformes: Batoideiomorpha). Instituto de Biologia, México.
CASTILLO-GENIZ, J. L., MARQUEZ-FARIAS, J. F., RODRIGUEZ DE LA CRUZ,
M. C., CORTÉS, E., CID DEL PRADO, A., 1998. The Mexican artisanal shark
fishery in the Gulf of México: towards a regulated fishery. Mar. Freshwat. Res. 49,
611-620.
KOHLER, N. E., CASEY, J. G., TURNER, P. A., 1995. Length-weight relationships
for 13 species of sharks from the western North Atlantic. Fish. Bull. 92, 412-418.
MOUTOPOULOS, D.K., STERGIOU, K.I., 2002. Length-weight and length-length
relationships of fish species from Aegean Sea (Greece). J. Appl. Ichthyol. 18(3), 200203.
NAKANO, H., 1999. Fishery management of sharks in Japan, p. 552-579. In:
SHOTTON, R. (ed.), Case studies of the man-agement of elasmobranch fisheries..
FAO Fisheries Technical Paper 378. FAO, Rome.
SCHWARTZ, F. J., BURGESS, G. H., 1975. Sharks of North Carolina and adjacent
waters. Information Series, North Carolina Department of Natural and Economic
Resources, Division of Marine Fisheries, Morehead City, North Carolina.
200
SHOTTON, R., 1999. Species identification practices of countries reported landings of
chondrichthyan fishes in the FAO nominal catches and landings data base, p. 904920. In: Case studies of the management of elasmobranch fisheries. R. Shotton (ed.).
FAO Fisheries Technical Paper 378. FAO, Rome.
WALKER, T. I., 1999. Southern Australian shark fishery management, p. 480-514. In:
SHOTTON, R. (ed.), Case studies of the management of elasmobranch fisheries..
FAO Fisheries Technical Paper 378. FAO, Rome.
201
Proc. of the Int. Workshop on Med. Cartilaginous Fish with Emphasis on South.- East. Med., 14-16 Oct. 06, Istanbul-Turkey
SHARK EXPLOITATION AND CONSERVATION IN SYRIA
Adib SAAD1, Malek ALI2 and Bernard SERET3
1, 2
Marine Sciences Laboratory, Fac. of Agr. Tishreen University, Lattakia, Syria.
E-mail: adibsaad@scs-net.org
3
Lbortoire d’Ichthyologie, Museume d’Histoire Naturelle, Paris, France
Abstract
Sharks are vulnerable to over fishing because they are long-lived, take many years to
mature, and only have a few youngs at a time. To provide protection and rebuild and
maintain sustainable shark fisheries, the Laboratory of Marines Sciences at Tishreen
University has been conducting since 2001 a research program on shark monitoring,
distribution and exploitation off the Syrian coast.
Data collection programs, permitting and reporting requirements, identification
of essential fish habitat, by-catch reduction of sharks in all fisheries, and promoting
safety at sea for shark fishermen.
Thirty-nine cartilaginous fish species including 22 shark species have been
recorded in the Mediterranean Syrian water. Some of these species are commercially
important and have been exploited over the ages as target species or bycatch, while
others are rare or very rare, and therefore have not been recorded on a regular basis. Due
to the negative impact of irresponsible fisheries on sharks, a decline of some shark
populations has been observed. The aim of this paper is to present the status of sharks in
the Mediterranean coast of Syria and to propose some measures for their conservation
and better management of their exploitation.
Key words: Sharks, exploitation, conservation, Mediterranean, Syria.
Introduction
Cartilaginous fishes off the Syrian coast have not been studied systematically as yet.
Only one work was realized during the last century ( GRUVEL, 1931) in which was
reported the presence of 15 species of Chondrichthiyes in Syrian Coast . Recently ALI
and SAAD (2003) reported 22 species, and SAAD et. al (2004) presented a commented
list of 37 Chondrichiteyes species living in Syrian coast.
Despite the sharks and rays constitute important resources within Syrian
fisheries, there is a lack of information on the landings and on the biology, distribution
and abundance of their populations in Syrian waters.
As a result, the Marine Sciences Laboratory (MSL) at the Faculty of
Agriculture, Tishreen University have undertaken a research programme on these fishes,
its objectives are:
202
-Inventory of cartilaginous fish species living in the Syrian coast (Eastern
Mediterraneansea)
- Identification and determination of catch composition of cartilaginous fish
- Study of exploitation level of shark fish
- Determination of threats to the cartilaginous fish stock
The purpose of this work is to present a preliminary field survey of the
cartilaginous fish study and their exploitation state of the Syrian coast
Materials and Methods
The area investigated is situated between the border of Turkey (in North) and border of
Lebanon (in south), to a depth of 25 to 1800 m; its about 180 x 20 = 3600 square km.
Samples were obtained by fishing with long- line and trawl (some time by
beach seine) during 2001-2004 in the Syrian waters. The main line, firm braided nylon
rope, 4.7 mm in diam., was held to the bottom by weights distributed along its length
and anchored by a 30-50 kg iron sinker. Every 5-10 m a 1.2 mm diam., monofilament
branch, 100-150 cm long, was attached to the main-line by a snap-on connector and
swivel. The hooks were ringed no.6, 7 and 8 or Mustad tuna circle hooks no. 8 and 9,
and were connected to the branches by 10 cm-long. 1 mm diam.stainless steel wire, in
order to prevent sharks from cutting the branchline. The bait consisted primarily of
Sparidae (Boops boops, Diplodus sp., Pagellus sp., Lithognathus mormyrus ect.)
Mesurments and counts follow COMPAGNO (1984), WHITEHEAD et al.
1984, FISCHER et al. (1987), GOLANI (1987), and NELSON (1994). All
measurement and calculation refer to total length (TL). The following parameters were
recorded in landing place or in laboratory (for the small specimens), for each individual
of fish: total weight, total length, sex and stage of maturity. In particular the maturity of
males can be easily and best defined from the state of development of the mixopterygia.
Maturity of females must be determined by internal examination. The
described specimens have been deposited in the Laboratory of Marine Sciences- Faculty
of Agriculture at Tishreen University, Fish collection (MLS).
203
Figure 1. Area of study on the Syrian coast: ■ = places of fish landing and sampling
Results and Discussion
At present, sharks and rays comprise 39 species in Mediterranean Syrian coast (Table1)
and represent 14.9 % of total marine species number and 3.4% of total marine catch in
weight (ALI, 2003), whereby most of them have a slow growth rate, late sexual
maturity and a low number of eggs or offspring.
Such characteristics reflect a low increase in population size, combined with a
strong susceptibility to every type of fishing. Managing their populations is thus
indispensable, but unfortunately, the majority of the fisheries which have developed
worldwide do not give this any consideration.
In addition, many of the large-sized shark and ray species demonstrate
extensive migration behavior, making it just as imperative that national and
international agreements are established to regulate their management.
Authorities concerned must give high priority to the management of sharks and
rays because these animals with their slow population growth rates are very susceptible
to overfishing and hence collapse of their populations (CASTRO et al., 1999).
204
The data obtained in this study have discovered for first time the presence of
Torpedo (Torpedo) sinuspersici Olfers, 1831 (SAAD et al., 2004) and confirmed the
presence of Dalatias licha in the eastern Mediterranean, as observed by GILAT and
GELMAN (1984). However, in the present study, the use of long-lining scatter baits
made them more accessible to smaller species.
Some other aspects, such as the presence of recruits both between 200 and 400
m and between 400 and 650 m, a greater percentage of mature individuals in the
mesobathyal than in epibathyal and homoeothermic condition in the bathyal
environment of Mediterranean, indicate, in our opinion, that the reproduction occurs at
the lowest depths at which the species is found. In the first years of life, Galeus
melastomus is distributed on a wide bathemtric bathyal slope, probably because of the
different feeding requirements of the young compared to those of the adult
(QUIGNARD and TOMASINI, 2000) and , successively, it moves to greater depths
investigated, reproducing and concluding its life cycle.
Further studies and collection of fish in the bathyal of Syrian marine waters are
necessary to increase our knowledge and understanding of the deep–water ichthyofauna
in this region.
Table 1. List of Cartilaginous fish species
work) and reported by GRUVEL (1931).
recorded in the Syrian coast (present
Gruvel
1931
Taxons
Sharks
HEXANCHIDAE
Hexanchus griseus (Bonnaterre, 1788)
Heptranchias perlo (Bonnaterre, 1788)
SQUALIDAE
Squalus acanthias Linnaeus, 1758
Squalus blainvillei (Risso, 1826)
Squalus sp. cf. megalops
CENTROPHORIDAE
Centrophorus granulosus (Bloch & Schn., 1801)
Centrophorus sp. cf. uyato (Rafinesque, 1809)
Centrophorus sp.
SOMNIOSIDAE
Somniosus rostratus (Risso, 1810)
OXYNOTIDAE
Oxynotus centrina (Linnaeus, 1758)
DALATIIDAE
Dalatias licha (Bonnatere, 1788)
SQUATINIDAE
Squatina aculeata Duméril in Cuvier, 1817
205
Present
work
*
*
+
*
*
+
*
*
*
*
*
*
*
Table 1. (Cont.)
Squatina oculata Bonaparte, 1840
Squatina squatina (Linnaeus, 1758)
ALOPIIDAE
Alopias superciliosus (Lowe, 1839)
LAMNIDAE
Isurus oxyrinchus Rafinesque, 1810
SCYLIORHINIDAE
Galeus melastomus Rafinesque, 1810
Scyliorhinus canicula (Linnaeus, 1758)
Scyliorhinus stellaris (Linnaeus, 1758)
TRIAKIDAE
Mustelus mustelus (Linnaeus, 1758)
Mustelus punctulatus Risso, 1826
CARCHARHINIDAE
Carcharhinus obscurus (Lesueur, 1818)
Carcharhinus plumbeus (Nardo, 1827)
SPHYRNIDAE
Sphyrna zygaena (Linnaeus, 1758)
RYS
PRISTIDAE
Pristis pectinata Latham, 1794
RHINOBATIDAE
Rhinobatos cemiculus Geof. St Hilaire, 1817
G. St Hilaire, 1817
Rhinobatos rhinobatos (Linnaeus, 1758)
TORPEDINIDAE
Torpedo (Tetronarce) nobiliana Bonaparte, 1835
Torpedo (Torpedo) marmorata Risso, 1810
Torpedo (Torpedo) sinuspersici Olfers, 1831
Torpedo (Torpedo) torpedo (Linnaeus, 1758)
RAJIDAE
Dipturus oxyrhynchus (Linnaeus, 1758)
Raja clavata Linnaeus, 1758
Raja miraletus Linnaeus, 1758
Raja montagui Fowler, 1910
Raja radula Delaroche, 1809
DASYATIDAE
Dasyatis pastinaca (Linaeus, 1758)
Dasyatis sp. cf. tortonesei Capapé, 1977
Pteroplatytrygon violacea (Bonaparte, 1832)
GYMNURIDAE
206
+
*
*
*
*
+
+
+
*
*
*
*
*
*
+
*
+
*
*
+
*
*
*
+
+
+
*
*
*
*
+
*
*
*
Table 1. (Cont.)
Gymnura altavela (Linnaeus, 1758)
MYLIOBATIDAE
Myliobatis aquila (Linnaeus, 1758)
Pteromylaeus bovinus (Geof. St Hilaire, 1817)
RHINOPTERIDAE
Rhinoptera marginata (Geof. St. Hilaire, 1817)
MOBULIDAE
Mobula mobular (Bonnatere, 1788)
CHIMERA
CHIMAERIDAE
Chimaera monstrosa Linnaeus, 1758
Total number of Shark species
Total nuber of Rays species
Total nuber of Chemera species
Total number of Condrichthias species
*
+
*
*
*
+
7
7
1
15
*
22
16
1
39
Exploitation
The Chondrichthyes species found at present in the Syrian marine waters can
be divided to three groups according to its economical importance:
Very economically important species being caught in plentiful quantities and
highly consumable: Carcharhinus plumbeus, Mustelus mustelus Centrophorus uyato,
Rhinobatos cemiculus, Hexanchus griseus, Squalus sp.cf. blanvllei,
Moderate economically important species either for being caught in little
quantities with high efforts in fishing, or for their little demand for human consumption,
or may be both reasons: Heptranchias perlo, Isurus oxyrinchus, Alopias superciliosus,
Carcharhinus obscurus,Dalatias licha, Somniosus rostratus, Squatina squatina,
Squatina oculata, Squatina aculata, Rhinobatos rhinobatos, Torpedo marmorata,
torpedo nobiliana Raja oxyrinchus, Raja clavata,Raja radula, Dasyatias sp. cf.
tortonesei, Dasyatis violacea, Centrophorus granulosus, Centrophorus moluccensis,
Squalus megalops, Gymnura altavela, Pteromylaeus bovinus, Mobula mobular.
Not economically important species with no demand for human consumption
or caught in little quantities: Galeus melastomus, Scyliorhinus canicula Oxynotus
centrina, Torpedo sp. cf. sinuspersici ,Chimaera monstrosa,Centrophorus acus.
The total fishing quantity of Chondrichthyes during 2002 amounted to 13020
fish, with a total weight of / 85.6 / Tons (ALI, 2003)
Further studies elasmobranches of Syrian marine water are necessary to
evaluate with precision the commercial importance of sharks and rays in the marine
fisheries and to propose the adequate methods for conservation.
207
References
ALI, M., 2003. Systematic and Economical Study of Cartilaginous fish in Syrian marine
waters, MSc Thesis, Tishreen University, pp 64 (in Arabic with Summary in English).
ALI, M., SAAD, A., 2003. Sharks nand Rays in Syrian Sae waters. al-Assad Journal
For Engineering Sciences. No. 17, 45-76 (in Arabic with abstract in English).
CADENAT, J., BLANCHE, J., 1981. Requins de Mediterranee et de l’Atlantique.
Faune Trop. OROSTOM, 21, pp 330.
CASTRO, J. I., WOODLY, C. M., BRUDEK, R. L., 1999. A preliminary evaluation of
the status of shark species. FAO fisheries technical paper. No. 380, Rome, 72 p.
COMPAGNO, L. J. V., 1984. FAO Species catalogue vol.4, part1: shark of the world:
an annotated and illustrated catalogue of shark species known to date. FAO fisheries
Synop.No125. FAO, Rome, Italy. 249 p
COMPAGNO, L., J., V., 1984a. FAO species catalogue. Vol. of the world. An annoted
and illustrated catalogue of shark species known to date. Part.1. Hexanchiformes to
Lamniformes. Synop.125, 251-655.
COMPAGNO,L., J.,V., 1984b. FAO Species catalogue vol.4, part 2:shark of the world:
an annotated and illustrated catalogue of shark species known to date. FAO fisheries
Synop. No.125. FAO,Rome, Italy. pp 251-655.
FAO, 2000. Fish and Fisheries vol 1, FAO, Rome, pp 210.
FISCHER,W, BOUCHOT, M. L., SCHNEIDER, M., 1987. Fiches FAO identification
des especes pour les besoins de la peche, Mediterranee et mer Noir,Zone de peche
37, Vol. II, pp 761-1530 .
GILAT, E., GELMAN, A., 1984. On the sharks and fishes observed using underwater
photography during a deep-water cruise in the Eastern Mediterranean. Fish. Res. 2,
257-271.
GOLANI, D., 1987. On deep water sharks caught off the Mediterranean sea of Israel.
Is. Jour. Zool. 34, 23-31.
GRUVEL, A., 1931. Les Etats de Syrie.Richesses marines et fluviales .Exploitation
actuelle et Avenir. Soc. Edit Geogr, Marit. et Colon, Paris, pp 453.
NELSON, J. S., 1984. Fishe of the world. 2nd edition, Awiley-intercience publication,
New york, Chichester, Brisban,Torento, Singapour, pp 523.
NELSON J. S., 1994. Fishes of the World. John Wiley , and Sons, INC, pp 600.
QUIGNARD, J. P., TOMASINI, J. A., 2000. Mediterranean Fish Bidiversity. Biol.
Mar. Medit. 7(3), 1-66.
SERET, B., 1990. Les requins :questions et reponses . Revue du palais de la
Decouverte Vol .18., No : 180, pp 19 –42.
SAAD, A., SERET, B., ALI, M. 2004. Liste commentée des Chondrichthyens de
Syrie ( Méditerranée orientale). Rapp. Comm.in . Mer.Medit. 37, 430.
TORTONESE, E., 1960. General remarks on the Mediterranean deep-sea fishes. Bull.
Inst. Oceanogr., Monaco 1167, 1-14.
WHITEHEAD, P. J. P., BAUCHOT, M. L., HUREAU, J. C., NIELSEN, J.,
TORTONESE, E., 1984. Fishes of the North-eastern Atlantic and the Mediterranean,
United Kingdom, Unesco, pp 510.
208
Proc. of the Int. Workshop on Med. Cartilaginous Fish with Emphasis on South.- East. Med., 14-16 Oct. 06, Istanbul-Turkey
FISHING AND CARTILAGINOUS FISHES ON ADRIATIC AND
IONIAN SEAS OF ALBANIA
Dritan ARAPI1, Rigerta SADIKAJ2 and Erida NELAJ2
1
Fishery Development Project, Ministry of Environment, Forestry and Water Administration - Albania.
d_arapi@hotmail.com
2
Agricultural University of Tirana, Department of Aquaculture - Albania.
Figure 1. Map of Albania
209
Abstract
This is a study done in 2004, in which results came from the specimens gathered by
fisherman’s catch. In our seas we have observed Mobula mobular, Sphyrna zygaena,
Squatina oculata which are very rare now in most parts of the Mediterranean Sea.
Introduction
The Republic of Albania is situated in South Eastern Europe, in the western part of the
Balkan Peninsula, facing the Adriatic and Ionian Sea to the west (Fig. 1). The Albanian
coastline is 427 km long from which:
• 273 km is of the sandy Adriatic coast (70% of the coast - sandy)
• 154 km of the rocky Ionian Coast (30% of the coast - rocky).
It includes the southeastern and southernmost shores of the Adriatic Sea, then
the eastern side of the Strait of Otranto connecting the Adriatic and Ionion seas, and the
northernmost Ionian shores that is a shoreline of 472 km from the Bunë estuary at the
Yugoslav frontier up to the Stilo cape in the Kékira (Corfu) channel at the Greek
frontier.
The Adriatic coast is generally low with many lagoons and beaches. The
process of accumulation is great because the rivers bring enormous quantities of solid
materials and the Adriatic Sea is shallow. The coastline has continuously developed in
seaward direction, especially during the last decades. This process has led to a rapid
development of lagoons such as Velipoja, Kunea-Merxhani, Patok and Karavasta,
formed in connection with the deltas of the rivers Buna, Drinit, Matit, Ishmit,
Shkumbin, Seman and Vjosa.
The Ionian coast is high and dominated by cliffs, except for some zones around
river mouths. Along the Ionian coast erosion prevails. This is why rugged cliffs and
sometimes caves have developed, e.g at Karaburun, Dhermi and Himarë.
In May 1990, the government of Albania signed the Barcelona Convention and
its four related protocols. Upon signing these documents, a number of activities were
launched within the framework of the Albanian programme of participation in the
Mediterranean Action Plan (MAP). At the meeting of the Scientific-Technical
Committee of MAP held in 1991, the Albanian delegation proposed that Coastal Area
Management Programme (CAMP) would be initiated in 1992. The proposal was
approved by the Seventh Ordinary Meeting of the Contracting Parties to the Barcelona
Convention and its Related Protocols in Cairo in 1991. In 1992 a draft agreement for the
CAMP was co-signed by the Albanian Government and MAP at the end of 1992. The
implementation of CAMPs thus pursues the task set as matter of priority at the
Conference of the United Nations on the Environment and Development (UNCED) with
its ‘Agenda 21’, which was held in Rio de Janeiro in 1992. The Ramsar Convention on
protection of the habitats of migratory birds and the ECE Convention on the Protection
and Use of Transboundary Watercourses and International Lakes have also been signed
and ratified.
210
Regarding to the legal and regulatory framework in Albania there is a law (No.
7908, dated 5.4.1995) on fishing and aquatic life. In relation to this law, it is prohibited:
a) To fish in areas and periods of time prohibited, with sailing means, fixed or movable
equipments prohibited, water organisms of prohibited species aiming at their protection;
fish eggs, larva or offspring of any water organism species without necessary
authorization or license based on by-laws for application of this law;
b) to use of explosive matters, of chemical or poisoning matters, of electrical energy
capable of stun, paralyze or kill water organisms, as well as during the aquatic life
activity.
In both seas, the Adriatic and Ionian seas, we can find a big number of
cartilaginous fishes where the most common families are: Rajidae, Lamnidae,
Triakidae, Oxynotidae, Scyliorhinidae, Sphyrhidae, Squalidae, Squatinidae,
Torpenididae, Mobulidae, etc.
Results and Discussion
Fishing Boats
Fishing in open sea is spread all over the coastline including territorial water from 12
miles away till the international waters. The biggest part of the fishing boats are trawlers
(39%) and trawl-sein (26%). The dynamic of fishing boats:
Fishing Boats
Trawler
Purse -seiner
Trawler-seiner
Lines -gill- nets
Gill net
Lines
Total
Number of boats
60
11
40
15
19
10
155
Total Fish Capture Estimates by Species (in kg), in 2004
Lamna nasus
Mobula mobular
Mustelus mustelus
Oxynotus centrina
Raja asterias
Raja clavata
Raja miraletus
Raja montagui
Raja oxyrinchus
Raja polystigma
Scyliorhinus canicula
Sphyraena sphyraena
17
3392
10293
20
240
10713
6
555
7
1120
670
43
211
%
39
7
26
10
12
6
100
96
1
4082
2059
Sphyrna zygaena
Squalus acanthias
Squatina oculata
Torpedo torpedo
2000
1500
1000
Raja clavata
Mustelus mustelus
Raja asterias
Raja polystigma
Scyliorhinus canicula Squatina oculata
D ec em ber
O c to b e r
S e p te m b e r
A ugust
J u ly
June
M ay
A p r il
M arch
F ebruary
Jannuary
0
N ovem ber
500
Raja montagui
Torpedo torpedo
Figure 2. Capture Estimates by month for the most common species (in kg), 2004
As shown in Figure 2, the biggest captures are between March and September
months, when the species that dominate are Mustelus mustelus, Raja clavata and also
Squatina oculata (from May to July) which is very rare in the Mediterranean sea.
Rare species which are presented in Red Book of Albania
1. Carcharodon carcharas L., 1758
Spread: Muzhel, Durres
Status: K (insufficiently known)
Provisions: To know better this species
2. Galeus melastomus Rafinesque, 1810
Spread: Low seaside of Albania
Status: R (rare)
Provisions: To know better this species
212
References
MISJA, K., BINO, T., PEJA, N. 1998. Red book of Albania “Cartilaginous species on
risk”, pp 99-102.
RAKAJ, N., FLLOKO, A. 1998. Iktiofauna e Shqiperise. pp. 55-138.
REC, 1997. Nature, Landscape and Biodiversity Conservation in Albania. Tirana,
Albania.
REPUBLIC OF ALBANIA. Law no. 8093, 21 March 1996, On Water Resources.
REPUBLIC OF ALBANIA, 2005. Ministry of Agriculture and Food, Directory of
Fishery, 2005 “Data of species captured during 2004”- Statistics.
SPAHO, V., 1995. Iktiologjia. 63-71.
UNEP/MAP., 1994. United Nations Environment Programme,‘Outline of the Coastal
Area Management Programme of Albania’, Tirana, Albania.
213
214
ANNEX I
CONCLUSIONS AND TECHNICAL ADVICE
Conclusions and technical advice from the Mediterranean meeting of experts on
cartilaginous fish held at Istanbul on October 2005 within the framework of the Action
Plan for the Conservation of Cartilaginous Fishes (Chondrichthyans) in the
Mediterranean Sea (UNEP-MAP-RAC/SPA):
1. By-catch and Discard
Conclusions
For the entire Mediterranean Sea by-catch and associated discards constitute a serious
threat for the elasmobranch species.
By catch reduction, while addressing that problem, helps also the efficiency of fisheries
targeting other species.
There are already some existent tools to reduce by-catch of elasmobranches. Some of
them show to be widely efficient (e.g. elimination of steel lines, trawler sorting-grids
and escaping devices).
Chondrichthyans by-catch in determined age classes (i.e. aged females) has a sound
effect on population depletion.
It is urgent to record elasmobranches capture amounts by species in order to allow their
fishery assessment and management .
Several management tools can be adopted, but a present priority in the Mediterranean is
to assess and specify which elasmobranch species are threatened.
Advice on actions
•
•
•
The use of steel lines to attach the hooks should be abandoned in the
Mediterranean region.
Capacity building should benefit fishermen in order to adapt gears whenever
recommended for environment protection purposes.
Fishing in cartilaginous mating, spawning and nursery grounds should be
avoided or regulated and monitored
215
•
•
•
•
Legal commercial sizes for cartilaginous, according to their life history, has to
be urgently defined in order to ensure sustainable exploited populations.
Therefore, it is necessary to establish also for the cartilaginous fishes a list of
the minimum capture sizes by species
Discards should be released back to sea as soon as possible to ensure highest
rates of survival
Studies on selectivity of the gears and their improvement regarding the
previous topic should be encouraged to reduce by-catch effects
Logbooks, landing sites, surveys and fishery observer programmes have to
record elasmobranches by species and assemble them in a common database
set
2. Information retrieval and diffusion
Conclusions
Standard protocols to record catch, fishing effort, rare species, etc need to be used in the
whole Mediterranean region.
There exists widespread confusion regarding local names of cartilaginous species in the
fishermen communities. That problem affects proper record of data.
In spite that there are still many gaps regarding scientific knowledge of the biology of
the elasmobranch fishes, specific funding to address them has not been prioritised.
A jointly shared Mediterranean database on elasmobranch fishes is a priority. This
database should be freely consultable by the experts on the web .
Advice on actions
•
•
•
Protocol prepared by RAC/SPA within the framework of the Action Plan
should be used by all the coastal countries after being revised by experts from
all the Mediterranean area
The recommended reference book for cartilaginous taxonomy in the
Mediterranean will be the one being prepared by FAO for 2006.
A poster or plackets with pictures of the most rare as well as threatened species
of Mediterranean cartilaginous species, intended for identification by
fishermen, needs to be produced and distributed in each country.
216
•
•
•
Educational packages on the elasmobranches problems addressed to fishermen
and general public should be produced and widely distributed.
Allocation of scholarships regarding elasmobranches ecology should be
addressed by concerned funding institutions to improve expertise, especially in
the developing Mediterranean countries.
The database being prepared by RAC/SPA for the Mediterranean region and
MEDLEM Database are both complementary and necessary. All the coastal
countries should contribute with their data to them through their institutional
bodies. The voluntary contribution of other experts should be, as reduced as
possible, or filtered through national institutions.
3. Critical habitats
Conclusions
There exists initial information regarding the location of critical habitats for
cartilaginous in the Mediterranean. Some of them are very detailed while other ones
have less precise delimitations. That information is still limited and needs improvement.
Very specific populations of certain species use restricted habitats, but it is necessary to
further evaluate this aspect in the Region by using genetic tools.
Biogeography and genetic parallel studies may allow discriminating between the
elasmobranch Atlantic stocks and the Mediterranean ones.
Advice on actions
•
•
•
•
Standardised criteria aimed to decide if an area is critical for Mediterranean
species of cartilaginous fishes should be defined and agreed by the riparian
countries.
A standard list and a related map of critical habitats in the Mediterranean need
to be settled, starting from this workshop results, and revised every few years.
Monitoring the abundance and population structure of elasmobranchs, as well
as the biodiversity in the critical habitats must be prioritised in relation to other
areas.
Genetic research on Mediterranean elasmobranches populations should be
encouraged. For that purpose, the riparian countries should start to keep tissue
samples of these species.
217
4. Coordination and collaboration
Conclusions
Regarding collaboration, no specific Mediterranean association addressing the
conservation of sharks does exist so far. However, organisations such as IUCN and the
European Elasmobranch Association are being active on this matter since years. At the
same time Institutions such as GFCM and FAO play an important role regarding
elasmobranches on the issue.
Nevertheless the Mediterranean sea is lacking a single associative body, involved on
elasmobranch studies, embracing all the coastal countries.
Advice on actions
•
•
It is kindly proposed to RAC/SPA to present the conclusions of the present
meeting to the next meeting of the European Elasmobranch Association, to be
held in Monaco on November 2005.
At the same time, it is suggested to kindly propose to the EEA at that gathering
the idea to allow membership to all the Mediterranean countries, including the
southern and eastern ones, changing if possible and desired its name (not the
acronym) to Euromediterranean Elasmobranch Association.
218
ANNEX II
Draft protocols proposed by RAC/SPA for monitoring commercial landings and discards by
species, as well as for recording data on rarely observed, endangered and protected species
219
220
FAUNISTIC LIST 1
(COMMERCIAL)
DATE:_____ CAST:__
________
_____
CAPTURE
SAMPLED
(kg)
VESSEL:
TOTAL CAPTURE (kg)
TOTAL
C.
SPECIES
CODE w (gr)
SAMPLE
Nº
TOTAL C.
W (gr)
Nº
FISHES
SPECIES
Dentex dentex
Diplodus annularis
Alopias superciliosus
Alopias vulpinus
Diplodus sp.
Aphia minuta
Diplodus vulgaris
Argentina sphyraena
Dipturus batis
Arnoglossus laterna
Dipturus oxyrinchus
Arnoglossus rueppelli
Echinorhinus brucus
Arnoglossus spp
Engraulis encrasicolus
Arnoglossus thori
Epigonus denticulatus
Arnoglosus imperialis
Etmopterus spinax
Aspitrigla obscura
Eutrigla gurnardus
Bathysolea profundicola
Gadiculus argenteus
Blennius ocellaris
Gaidropsarus spp.
Boops boops
Galeorhinus galeus
C. caelorinchus
Galeus atlanticus
Callionymus maculatus
Galeus melastomus
Capros aper
Gnathophis mystax
Carcharhinus altimus
Gobius niger
Carcharhinus branchyurus
Helicolenus dactylopterus
Carcharhinus brevipinna
Heptranchias perlo
Carcharhinus falciformis
Hexanchus griseus
Carcharhinus limbatus
Hoplostethus mediterraneus
Carcharhinus obscurus
Isurus paucus
Carcharhinus plumbeus
Lamna nasus
Carcharias taurus
Lepidopus caudatus
Carcharodon carcharias
Lepidorhombus boscii
Carharhinus melanopterus
Lepidotrigla cavillone
Centrolophus niger
Lesueurigobius sanzoi
Centrophorus granulosus
Leucoraja circularis
Centrophorus ujato
Leucoraja fullonica
Centroscymnus coelolepis
Leucoraja melitensis
Cepola rubescens
Leucoraje naevus
Cetorhinus maximus
Leucoraje undulata
Citharus linguatula
Lophius budegassa
Conger conger
Lophius piscatorius
Chaulodius sloani
Lophius spp
Chelidonichthys obscurus
Macroramphosus scolopax
Chelidonichthys obscurus
Merluccius merluccius
Chimaera monstrosa
Micromesistius poutassou
Chlorophthalmus agassizi
Mobula mobular
D. quadrimaculatus
Mullus barbatus
Dalatias licha
Mullus surmuletus
Dasyatis centroura
Mustelus asterias
Dasyatis pastinaca
Mustelus mustelus
Figure 1. Species list for observers (trawling and purse seine)
221
SAMPLE
CODE
w (gr)
Nº
W (gr)
Nº
FAUNISTIC LIST 2 (COMMERCIAL)
VESSEL:
DATE:_____________
TOTAL C.
SPECIES
CODE w (gr)
Nº
SAMPLE
W (gr)
CAST:_______
TOTAL C.
Nº
SPECIES
FISHES
Sphyma zygaena
Mustelus punctulatus
Sphyrna lewini
Myctophum punctatum
Sphyrna mokarran
Myliobatis aquila
Spicara flexuosa
Nezumia aequalis
Spicara maena
Odontaspis ferox
Spicara smaris
Ophidion barbatum
Spondyliosoma cantharus
Oxynotus centrina
Squalus acanthias
Pagellus acarne
Squalus blainville
Pagellus bogaraveo
Squatina aculeata
Pagellus erythrinus
Squatina oculata
Pagrus pagrus
Squatina squatina
Peristedion cataphractum
Stomias boa
Phycis blennoides
Symphurus nigrescens
Phycis phycis
T. trachurus
Pomatoschistus spp.
Torpedo marmorata
Prionace glauca
Torpedo nobiliana
Pristis pectinata
Torpedo torpedo
Pristis pristis
Trachinus draco
Pteroplatytrygon violacea
Trachurus mediterraneus
Raja asterias
Trachurus picturatus
Raja branchyura
Trigla lucerna
Raja clavata
Trigla lyra
Raja miraletus
Trisopterus luscus
Raja montagui
Uranoscopus scaber
Raja naebo
Xiphias gladius
Raja polystigma
Zeus faber
Raja radula
Raja rondeleti (of fullonica)
Rhinobatos cemiculus
Rhinobatos rhinobatos
Rostroraja alba
Sardina pilchardus
Sardinella aurita
Scomber japonicus
Scomber scombrus
Scorpaena sp.
Scyliorhinus canicula
Scyliorhinus stellaris
Serranus cabrilla
Serranus hepatus
Solea vulgaris
Somniosus rostratus
Sphyma tudes
Figure 2. Species list (Second part)
222
CODE w (gr)
Nº
SAMPLE
W (gr)
Nº
FAUNISTIC LIST 3 (COMMERCIAL)
VESSEL:
DATE:_____________
TOTAL C. SAMPLE
SPECIES
CODE w (gr) Nº W (gr)
CRUSTACEAN
Alpheus glaber
Aristeus antennatus
Bathynectes maravigna
Calappa granulata
Dardanus arrosor
Geryon longipes
Goneplax rhomboides
Homarus gammarus
Liocarcinus depurator
Macropodia longipes
Munida sp.
Nephrops norvegicus
Pagurus sp.
Parapenaeus longirostris
Pasiphea sivado
Plesionika edwardsii
Plesionika giglioli
Plesionika heterocarpus
Plesionika martia
Plesionika sp.
Pontocaris spp.
Solenocera membranacea
Squilla mantis
Nº
SPECIES
MOLLUSKS
Alloteuthis sp.
Alloteuthis media
Alloteuthis subulata
Eledone cirrhosa
Eledone moschata
Illex coindetti
Loligo vulgaris
Octopus salutii
Octopus vulgaris
Opistobranchia spp.
Pecten maximus
Sepia elegans
Sepia officinalis
Sepia orbignyana
Sepietta spp.
Sepiola spp.
Todarodes spp.
Cassidaria tyrrhena
Sepia spp
Venus nux
Todaropsis eblanae
OTHERS
Echinoidea
Asteroidea
Holothurioidea
Ophiuroidea
Without sorting
Plastic
Glass
Metal
Coal
Organic matter
Inorganic matter
Wood
Figure 3. Species list ( third part)
223
CAST:_______
TOTAL C.
COD
w (gr) Nº
E
SAMPLE
W (gr)
Nº
FAUNISTIC LIST 1 (DISCARDS)
VESSEL:
DATE:_____________
TOTAL CAPTURE
CAPTURE SAMPLED (kg)
SPECIES
CODE
TOTAL C. SAMPLE
w (gr) Nº
W
Nº
SPECIES
FISHES
Dentex dentex
Alopias superciliosus
Diplodus annularis
Alopias vulpinus
Diplodus sp.
Aphia minuta
Diplodus vulgaris
Argentina sphyraena
Dipturus batis
Arnoglossus laterna
Dipturus oxyrinchus
Arnoglossus rueppelli
Echinorhinus brucus
Arnoglossus spp
Engraulis encrasicolus
Arnoglossus thori
Epigonus denticulatus
Arnoglosus imperialis
Etmopterus spinax
Aspitrigla obscura
Eutrigla gurnardus
Bathysolea profundicola
Gadiculus argenteus
Blennius ocellaris
Gaidropsarus spp.
Boops boops
Galeorhinus galeus
C. caelorinchus
Galeus atlanticus
Callionymus maculatus
Galeus melastomus
Capros aper
Gnathophis mystax
Carcharhinus altimus
Carcharhinus
branchyurus
Carcharhinus brevipinna
Gobius niger
Heptranchias perlo
Carcharhinus falciformis
Hexanchus griseus
Helicolenus dactylopterus
Carcharhinus limbatus
Hoplostethus mediterraneus
Carcharhinus obscurus
Isurus paucus
Carcharhinus plumbeus
Lamna nasus
Carcharias taurus
Lepidopus caudatus
Carcharodon carcharias
Carharhinus
melanopterus
Centrolophus niger
Lepidorhombus boscii
Lesueurigobius sanzoi
Centrophorus granulosus
Leucoraja circularis
Centrophorus ujato
Centroscymnus
coelolepis
Cepola rubescens
Leucoraja fullonica
Cetorhinus maximus
Leucoraje undulata
Lepidotrigla cavillone
Leucoraja melitensis
Leucoraje naevus
Citharus linguatula
Lophius budegassa
Conger conger
Lophius piscatorius
Chaulodius sloani
Lophius spp
Chelidonichthys obscurus
Macroramphosus scolopax
Chelidonichthys obscurus
Merluccius merluccius
Chimaera monstrosa
Micromesistius poutassou
Chlorophthalmus agassizi
Mobula mobular
D. quadrimaculatus
Mullus barbatus
Dalatias licha
Mullus surmuletus
Dasyatis centroura
Mustelus asterias
Dasyatis pastinaca
Mustelus mustelus
Figure 4. Species discarded List for observers.
224
CAST:_______
TOTAL C. SAMPLE
COD w (gr) Nº
W
Nº
FAUNISTIC LIST 2 (DISCARDS)
VESSEL:
DATE:_____________
TOTAL C.
SPECIES
CODE
w (gr)
CAST:_______
SAMPLE
Nº
W (gr)
FISHES
TOTAL C.
Nº
SPECIES
Sphyma zygaena
Mustelus punctulatus
Sphyrna lewini
Myctophum punctatum
Sphyrna mokarran
Myliobatis aquila
Spicara flexuosa
Nezumia aequalis
Spicara maena
Odontaspis ferox
Spicara smaris
Ophidion barbatum
Spondyliosoma cantharus
Oxynotus centrina
Squalus acanthias
Pagellus acarne
Squalus blainville
Pagellus bogaraveo
Squatina aculeata
Pagellus erythrinus
Squatina oculata
Pagrus pagrus
Squatina squatina
Peristedion cataphractum
Stomias boa
Phycis blennoides
Symphurus nigrescens
Phycis phycis
T. trachurus
Pomatoschistus spp.
Torpedo marmorata
Prionace glauca
Torpedo nobiliana
Pristis pectinata
Torpedo torpedo
Pristis pristis
Trachinus draco
Pteroplatytrygon violacea
Trachurus mediterraneus
Raja asterias
Trachurus picturatus
Raja branchyura
Trigla lucerna
Raja clavata
Trigla lyra
Raja miraletus
Trisopterus luscus
Raja montagui
Uranoscopus scaber
Raja naebo
Xiphias gladius
Raja polystigma
Zeus faber
Raja radula
Raja rondeleti (of fullonica)
Rhinobatos cemiculus
Rhinobatos rhinobatos
Rostroraja alba
Sardina pilchardus
Sardinella aurita
Scomber japonicus
Scomber scombrus
Scorpaena sp.
Scyliorhinus canicula
Scyliorhinus stellaris
Serranus cabrilla
Serranus hepatus
Solea vulgaris
Somniosus rostratus
Sphyma tudes
Figure 5. Species discarded list (second part)
225
CODE
w (gr)
SAMPLE
Nº
W (gr)
Nº
FAUNISTIC LIST 3 (DISCARDS)
VESSEL:
DATE:_____________
TOTAL C.
SPECIES
CODE
w (gr)
CAST:_______
SAMPLE
Nº
W (gr)
TOTAL C.
Nº
SPECIES
CRUSTACEAN
MOLLUSKS
Alpheus glaber
Alloteuthis sp.
Aristeus antennatus
Alloteuthis media
Bathynectes maravigna
Alloteuthis subulata
Calappa granulata
Eledone cirrhosa
Dardanus arrosor
Eledone moschata
Geryon longipes
Illex coindetti
Goneplax rhomboides
Loligo vulgaris
Homarus gammarus
Octopus salutii
Liocarcinus depurator
Octopus vulgaris
Macropodia longipes
Opistobranchia spp.
Munida sp.
Pecten maximus
Nephrops norvegicus
Sepia elegans
Pagurus sp.
Sepia officinalis
Parapenaeus longirostris
Sepia orbignyana
Pasiphea sivado
Sepietta spp.
Plesionika edwardsii
Sepiola spp.
Plesionika giglioli
Todarodes spp.
Plesionika heterocarpus
Cassidaria tyrrhena
Plesionika martia
Sepia spp
Plesionika sp.
Venus nux
Pontocaris spp.
Todaropsis eblanae
Solenocera membranacea
Squilla mantis
OTHERS
Echinoidea
Asteroidea
Holothurioidea
Ophiuroidea
Without sorting
Plastic
Glass
Metal
Coal
Organic matter
Inorganic matter
Wood
Figure 6. Discarded species list (third part)
226
CODE
w (gr)
SAMPLE
Nº
W (gr)
Nº
BY-CATCH & DISCARDS
SIZE DISTRIBUTIONS
Vessel:...............................
SET:
DATE:
Species:___
Code:
Species:________
__
Category:
Code:
__
Category:
Total weight: ____
Species:_________
__
Code:
___
______
Category:
Total weight: ___
____
Total weight:
Sample weight: ___
Sample weight:__
Sample weight: ______
Minimum size: _____
Minimum size:__
Minimum size: _______
Maximum size: _______
Maximum size:
_
cm
Maximum size: ______
cm
cm
0
0
0
1
1
1
2
2
2
3
3
3
4
4
4
5
5
5
6
6
6
7
7
7
8
8
8
9
9
9
0
0
0
1
1
1
2
2
2
3
3
3
4
4
4
5
5
5
6
6
6
7
7
7
8
8
8
9
9
9
0
0
0
1
1
1
2
2
2
3
3
3
4
4
4
5
5
5
6
6
6
7
7
7
8
8
8
9
9
9
0
0
0
Figure 7. Form for discards quantification in trawling and longline fisheries.
227
BY-CATCH & DISCARDS
SIZE DISTRIBUTIONS
Vessel:...............................
SET:
DATE:
Species:______
Species:_______
Code:
Code:
_____
Category:
___
Category:
Species:_____
______
Code:
____
_____
Category: ____
Total weight: ___
Total weight: ___
Total weight: ___
Sample weight: ____
Sample weight: ____
Sample weight: ___
Minimum size: ____
Minimum size: ____
Minimum size:____
Maximum size: ____
Maximum size: ____
Maximum size:_____
cm
cm
cm
0
0
0
0,5
0,5
0,5
1
1
1
1,5
1,5
1,5
2
2
2
2,5
2,5
2,5
3
3
3
3,5
3,5
3,5
4
4
4
4,5
4,5
4,5
5
5
5
5,5
5,5
5,5
6
6
6
6,5
6,5
6,5
7
7
7
7,5
7,5
7,5
8
8
8
8,5
8,5
8,5
9
9
9
9,5
9,5
9,5
0
0
0
0,5
0,5
0,5
1
1
1
1,5
1,5
1,5
2
2
2
2,5
2,5
2,5
3
3
3
3,5
3,5
3,5
4
4
4
4,5
4,5
4,5
5
5
5
Figure 8. Form for discards quantification in purse seine fishery.
228
COMMERCIAL
SIZE DISTRIBUTIONS
Vessel:...............................
SET:
DATE:
Species:_________________
Species:_________________
Code:
_______
Code:
_______
Species:_________________
Code:
_______
Category:
_______
Category:
_______
Category:
_______
Total weight:
_______
Total weight:
_______
Total weight:
_______
Sample weight:
_______
Sample weight:
_______
Sample weight:
_______
Minimum size:
_______
Minimum size:
_______
Minimum size:
_______
Maximum size:
_______
Maximum size:
_______
Maximum size:
_______
cm
cm
cm
0
0
0
1
1
1
2
2
2
3
3
3
4
4
4
5
5
5
6
6
6
7
7
7
8
8
8
9
9
9
0
0
0
1
1
1
2
2
2
3
3
3
4
4
4
5
5
5
6
6
6
7
7
7
8
8
8
9
9
9
0
0
0
1
1
1
2
2
2
3
3
3
4
4
4
5
5
5
6
6
6
7
7
7
8
8
8
9
9
9
Figure 9. Form for lengths and weights quantification in trawling and longline fisheries.
229
COMMERCIAL
SIZE DISTRIBUTIONS
Vessel:...........................
SET:
DATE:
Species:___________
Species:________
Code:
Code:
_____
Category:
Total weight:
____
Category:
_____
Species:___________
_
Code:
_______
Category:
Total weight: _______
_______
______
Total weight: _______
Sample weight: _____
Sample weight:______
Sample weight: _____
Minimum size: _____
Minimum size:_______
Minimum size: ______
Maximum size: ____
Maximum size
Maximum size:______
_____
cm
cm
cm
0
0
0
0,5
0,5
0,5
1
1
1
1,5
1,5
1,5
2
2
2
2,5
2,5
2,5
3
3
3
3,5
3,5
3,5
4
4
4
4,5
4,5
4,5
5
5
5
5,5
5,5
5,5
6
6
6
6,5
6,5
6,5
7
7
7
7,5
7,5
7,5
8
8
8
8,5
8,5
8,5
9
9
9
9,5
9,5
9,5
0
0
0
0,5
0,5
0,5
1
1
1
1,5
1,5
1,5
2
2
2
2,5
2,5
2,5
3
3
3
3,5
3,5
3,5
4
4
4
4,5
4,5
4,5
5
5
5
Figure 10. Form for lengths and weights quantification in purse seine fishery (commercial species).
230
SIZE OF SPECIES CAPTURED (LOWESTcm)
SWORDFISH
LJFL
BLUEFIN
TUNA
ALBACORE
FL
FL
SHORTFIN
MAKO
BLUE SHARK
FL/TL
COMMON
THRESHER
FL/TL
FL/TL
BIGEYE THRESHER SPHYRNA SP.
FL/TL
FL/TL
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
COMMERCIAL CAPTURE
Number of retained
fishes
Species
H CAPTURE
Weight
retained
Number of
discarded fishes
Species
Number of
specimens alive
Number of specimens
dead
Swordfish
Bluefin tuna
Albacore
Skipjack tuna
Blue shark
Shortfin Mako
Common Thresher
Shark
Bigeye thresher shark
Sphyrna zigaena
Other
Total
Total
Figure 11. Form for lengths and weights data collection of target and by-catch species (Longline).
231
Fishing Data
Set Code:
Observer:
Departure date:
Vessel:
Landing date:
Base Port:
Landing port:
1. FISHING EFFORT
Fishing gear/Target species
Bait type (% of species)
Number of hooks (% sizes)
Bait size:
Fluorescent baits (% and colour)
2. CAST SPECIFICATIONS
CAST
START
END
TACK
Situation
Situation
Date
Date
Time
Time
Depth
Depth
Temperature
Temperature
Sea state
Sea state
Wind strength
Wind strength
Wind direction
Wind direction
Lunar stage
Lunar stage
START
Miles covered
Distance to Coast
Distance to Coast
Changes of direction
Time:
Situation:
Time:
Situation:
Time:
Situation:
Time:
Situation:
Fishing incidents and other remarks
Figure 12. Fishing form for gathering data on longline fisheries.
232
END
I
Start time
End time
II
Start time
End time
III
Start time
End time
IV
Start time
End time
V
Start time
End time
VI
Start time
End time
VII
Start time
End time
VIII
Start time
End time
IX
Start time
End time
X
Start time
End time
XI
Start time
End time
XII
Start time
End time
XIII
Start time
End time
XIV
Start time
End time
XV
Start time
End time
Figure 13. Fishing form for gathering data on longline fisheries (catches by gear units).
233
ON BOARD OBSERVERS::::::::::::::::::::::::::::::::::::::::::::::
SET FORM:;;:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: ::
VESSEL.............. ......
FISHING GEAR.......
TYPE OF DOOR
WEIGHT DOOR
NUMBER OF SETS…………
DATE (DAY/MONTH/YEAR)
CABLE LARGADO (m)
DISTANCE TO COASTLINE (m)
_____________________
_____________________
_____________________
............................Beginning................................................................................................................
............
TIME (hour, minutes).................. ..
LATITUDE (degree, minutes).........
LONGITUDE (degree, minutes)......
DEPTH (meters)............. ........ .......
__________________________
________ . ______________N
________ . ______________W
_________________
............................Finishing...................................................................................................................
........
TIME (hour, minutes).................. ..
LATITUDE (degree, minutes).........
LONGITUDE (degree, minutes)......
DEPTH (meters)............. ........ .......
__________________________
________ . ______________N
________ . ______________W
_________________
COURSE (degree) :
VELOCITY/SPEED (knot) :
GENERAL WEATHER CONDITIONS
CLOUDINESS ( 1/8 – 8/8 ):
RAINFALL:
WIND STRENGTH (calm, breeze, light, storm):
WIND DIRECTION:
SEA STATE
SEA STATE (calm, slight swell, swell, heavy swell):
º
º
GPS
DEPTH
FINDER
LATITUDE
LONGITUDE
COURSE
TIME
DEPTH
Figure 14. Set form to be filled by observers on board of trawling vessels.
234
ON BOARD OBSERVERS .::::::::::::::::::::::::::::::::::::::::::::::::
SET FORM:;;:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
VESSEL.............. ......
FISHING GEAR.......
NUMBER OF SETS…………
DATE (DAY/MONTH/YEAR)
CABLE HAULED IN (m)
DISTANCE TO COASTLINE (m)
_____________________
_____________________
_____________________
............................Begining.....................................................................................................................
.......
TIME (hour, minutes).................. ..
LATITUDE (degree, minutes).........
LONGITUDE (degree, minutes)......
DEPTH (meters)............. ........ .......
__________________________
________ . ______________N
________ . ______________W
_________________
COURSE (degree) :
VELOCITY/SPEED (knot) :
GENERAL WEATHER CONDITIONS
CLOUDINESS ( 1/8 – 8/8 ):
RAINFALL:
WIND STRENGTH (calm, breeze, light, storm):
WIND DIRECTION:
SEA STATE
SEA STATE (calm, slight swell, swell, heavy swell):
º
º
GPS
DEPTH
FINDER
LATITUDE
LONGITUDE
COURSE
TIME
DEPTH
Figure 15. Set form to be filled by observers on board of longline vessels.
235
PORT:_________________________
VESSEL
DATE:_____________________ LOCAL TIME:____________________
FISHING GROUND
FISHING
TRIPS
NUMBER OF
SETS
AVERAGE
SETS
DURATION
Figure 16. Shoreside sampling form for trawling gear.
236
DEPTH
DURATION OF
FISHING TRIPS ( PREVIOUS
FISHING
MONTH)
OPERATIONS
PORT :__________________
Vessel
DATE:____________ LOCAL TIME:______________
Species/Category
Number of
boxes
Figure 17. Shoreside sampling form for purse seine
237
Total weight
Specimens
number
Specimens weight
PORT:
__________________________________
SPECIES:
__________________________________
REPORTER: ________________________________
VESSEL:
__________________________________
BIOLOGICAL SAMPLINGS
SPECIES
ROUND WEIGHT
SEX
MALE
FEMALE
INDET.
...............................................................
TOTAL
Figure 18. Accurate forms for bottom and surface longlines.
238
SIZE
TOTAL
LANDING PORT:________________________
INFORMER:________________________________
GEAR:____________________ BASE:______________
DATE:________________
VESSEL:___________________
Days at sea :____________ SETS:________ Hooks:___________ Bait:_______________
Miles: ___________ Hours:______________
POSITION
SETS
AREA
NUMBER---WEIGHT
SHORTFIN MAKO:
BLUE SHARK:
BYCATCH SPECIES
N
W
HAMMERHEAD SHARKS
BLUE SHARK(TOTAL)
SHORTFIN MAKO
THRESHER SHARK
CARCHARINUS
MEDITERRANEAN SPEARFISH
BLUEFIN TUNA
N
W
WAHOO (Acanthocybium.)
ALBACORE
YELLOWFIN TUNA
BIGEYE TUNA
WHITE MARLIN
ATLANTIC SAILFISH
BYCATCH SPECIES
SPECIES
sex
size
weight
sex
size
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
TOTAL
Figure 19. Forms for bottom and surface longlines
239
weight
sex
size
weight
STATISTIC AND SAMPLING NET
REPORTER:
Date Vessel Fishing gear Fishing area Species Specimen nº
Total
weight
PORT:
Fishing
days
Fishing
Effort
Remarks
Figure 20. Form designed for gathering temporal series of total fleet landing of each commercial
species.
240
OBSERVER - TRIP CODE
VESSEL
Number of sets
DEPARTURE DATE
ARRIVAL DATE
LANDING PORT
SALE TYPE
FISHING TRIPS DATA
.................................................
.................................................
.................................................
................................................
..................................................
SALE SPECIFICATIONS :
SPECIES
NUMBER
ROUND WEIGHT RW
DRESSED WEIGHT DW (kg)
(kg)
Swordfish
Bluefin tuna
Albacore
Blue shark
Shortfin Mako
Dolphin fish
Pomfret
IMPORTANT:
Please, when you note the weight, you must specify if it is round, dressed, gutted or trunk
weight
Figure 21. Forms designed for gathering temporal series of total fleet landing of each commercial
species
241
Vessel:______________________
Longline type:
Date:_______/_______/_______
Longline characteristics: depth: _____________ Hook distance: ______________
Hook size: ___________ Longline length: ______________ Bait:
Appelling Lights: yes ___ no ___ number ______
Situation at the
Situation at the
beginning of
end of fishing
fishing
operation
operation
Number of
hooks
Species
Number
Swordfish
Hours:
Fishing
operation
duration:
Bluefin tuna
Temperature :
Sea stage:
Albacore
Billfish
Observations:
Blue shark
Shortfin Mako
Thresher shark
Heptranquias
Dasyatis spp.
Other species
Figure 22. Example of logbooks form.
242
Weight
(average)
Individual weights:
swordfish / bluefin tuna/ albacore
24. In the event that my supervisor wishes to verify that I have been conducting interviews here today , may I have your name and phone number?
ANGLER´S NAME
D or N
PHONE # (__ __ __) __ __ __ - __ __ __ __
__ Name and phone number not given
25. UNAVAILABLE CATCH. Did you land any fish that are not here for me to look at? For example, any that you may have thrown back or use for
bait? IF YES, COMPLETE TYPE 2 RECORD FOR THIS INDIVIDUAL ANGLER. NOT GROUP CATCH. NOTE : FILLETS ARE
UNAVAILABLE CATCH.
DISPOSITION CODES FOR Q25
1. Thrown back alive/legal
2. Thrown back alive/not legal/legality refused
3. Eaten/plan to eat
4. Used for bait/plan to use for bait
5. Sold/plan to sell
6. Thrown back dead/plan to throw away
7.Some other purpose
TYPE 2 RECORDS: (INDIVIDUAL CATCH UNAVAILABLE IN WHOLE FORM)
SPECIES CODE
1.
_________________________________
__ __ __ __ __ __ __ __ __ __
2.
_________________________________
3.
_________________________________
4.
_________________________________
5.
_________________________________
6.
_________________________________
7.
_________________________________
26. Did you catch any fish while you were
fishing that I might be able to look at?
1
2
3
___
___
___
# OF FISH
__ __ __
DISP
__
29. How many anglers including yourself have their catch
here? Please de not include anyone who did not catch
fish. Only count those who have their catch here.
___ ___ No. Of Contributors 88___ Not Applicable
Yes
No – Code q. 27, 28, 29 as “8´s,”Not Applicable
Yes, BUT fish on another angler´s formFill interview # where fish are listed
BOX C. If q. 11 is SH mode, code q. 30 as “88”, and
Code Box D as”8”.
___ ___ -Code q. 27, 28, 29 as “8´s”Not Applicable
30. How many people fished on your boat today?
27. Did you catch these yourself or did
someone else catch some of them?
___ ___ No. of People
1. ___ All Caught by Angler – Code q. 28, 29, as “8´s”Not Applicable
2. ___ Other Contributors
8. ___ Not Applicable
88 ___ Shore Mode
Box D. If response to q. 30 is 1, code as “8”, Not Applicable.
Otherwise, is this the first angler from this boat that I have
interviewed?
28. Can you separate out your individual catch?
1. ___ Yes _ Code 29 as “88”
2. ___ No
31. AVAILABLE CATCH .
1. ___ Yes
8. ___ Not Applicable
2. ____ No –Record interview # of 1” angler
in the fishing party
___ ___
8. ___ Not Applicable
COMPLETE TYPE 3 RECORD BY ASKING: May I look at your fish? What do you plan to do with the
MAJORITY of the (species)?
DISPOSITION CODES FOR Q31
3. Eaten/plan to eat
4. Used for bait/plan to use for bait
5. Sold/plan to sell
6. Thrown back dead/plan to thrown away
7. Some other purpose
8. Don´t know/Didn´t ask
9. Refused
TYPE 3 RECORDS: (INDIVIDUAL CATCH AVAILABLE IN WHOLE FORM)
1.________________________
2.________________________
3.________________________
4.________________________
5.________________________
6.________________________
7.________________________
8.________________________
9.________________________
10._______________________
11._______________________
12._______________________
13._______________________
14._______________________
15._______________________
SPECIES CODE
___ ___ ___ ___ ___ ___ ___ ___ ___ ___
___ ___ ___ ___ ___ ___ ___ ___ ___ ___
___ ___ ___ ___ ___ ___ ___ ___ ___ ___
___ ___ ___ ___ ___ ___ ___ ___ ___ ___
___ ___ ___ ___ ___ ___ ___ ___ ___ ___
___ ___ ___ ___ ___ ___ ___ ___ ___ ___
___ ___ ___ ___ ___ ___ ___ ___ ___ ___
___ ___ ___ ___ ___ ___ ___ ___ ___ ___
___ ___ ___ ___ ___ ___ ___ ___ ___ ___
___ ___ ___ ___ ___ ___ ___ ___ ___ ___
___ ___ ___ ___ ___ ___ ___ ___ ___ ___
___ ___ ___ ___ ___ ___ ___ ___ ___ ___
___ ___ ___ ___ ___ ___ ___ ___ ___ ___
___ ___ ___ ___ ___ ___ ___ ___ ___ ___
___ ___ ___ ___ ___ ___ ___ ___ ___ ___
# OF FISH
___ ___ ___
___ ___ ___
___ ___ ___
___ ___ ___
___ ___ ___
___ ___ ___
___ ___ ___
___ ___ ___
___ ___ ___
___ ___ ___
___ ___ ___
___ ___ ___
___ ___ ___
___ ___ ___
___ ___ ___
Figure 23. Survey form.
243
LENGTH (mm)
___ ___ ___ ___
___ ___ ___ ___
___ ___ ___ ___
___ ___ ___ ___
___ ___ ___ ___
___ ___ ___ ___
___ ___ ___ ___
___ ___ ___ ___
___ ___ ___ ___
___ ___ ___ ___
___ ___ ___ ___
___ ___ ___ ___
___ ___ ___ ___
___ ___ ___ ___
___ ___ ___ ___
WEIGHT (kg)
___ ___ ___ · ___ ___
___ ___ ___ · ___ ___
___ ___ ___ · ___ ___
___ ___ ___ · ___ ___
___ ___ ___ · ___ ___
___ ___ ___ · ___ ___
___ ___ ___ · ___ ___
___ ___ ___ · ___ ___
___ ___ ___ · ___ ___
___ ___ ___ · ___ ___
___ ___ ___ · ___ ___
___ ___ ___ · ___ ___
___ ___ ___ · ___ ___
___ ___ ___ · ___ ___
___ ___ ___ · ___ ___
DISP
___
___
___
___
___
___
___
___
___
___
___
___
___
___
___
List of main species rarely observed, endangered, and protected in the Mediterranean.
Dipturus batis
Squalus megalops
Squatina aculeata
Squatina oculata
Squatina squatina
Carcharias taurus
Odontaspis feroz
Cetorhinus maximus
Carcharodon carcharias
Pristis pectinata
Pristis pristis
Figure 24. Second part of the survey form shown in Figure 23.
244
Data Collection about rare or threatened
species
Set
Hour
Species
FL
Tag Number
Condition
Figure 25. Example of form to collect data about rare or threatened species.
245
Remarks
Sightings of rare or threatened species
Position
Date
Time
Species
Specimen
number
Figure 26. Form to collect data about sightings of rare or threatened species.
246
Remarks
Data collection in oceanographic cruises
Catch of main species
Date: __________________
Depth:____________________
Time:___________________
Latitude:__________________
Longitude:_________________
General weather conditions
Cloudiness (1/8 – 8/8):
Rainfall:
Wind strength (calm, breeze, light, storm):
Wind direction:
Sea state
Sea state (calm, slight swell, swell, heavy swell):
Vessel name:
Fishing gear:
Port:
Number of animals:_____________
State of the animals:
-
Alive:
Dead:
In state of putrefaction:
In a very advanced state of putrefaction:
Fragmented:
____
____
____
____
____
Nº: ____
Nº: ____
Nº: ____
Nº: ____
Nº: ____
Figure 27. Form to use in fishing scientist surveys to collect general oceanographic data and
general condition data of target species.
247
By-catch species
Date: __________________
Depth:____________________
Time:___________________
Latitude:__________________
Longitude:_________________
General weather conditions
Cloudiness (1/8 – 8/8):
Rainfall:
Wind strength (calm, breeze, light, storm):
Wind direction:
Sea state
Sea state (calm, slight swell, swell, heavy swell):
Vessel name:
Fishing gear:
Port:
State of animals:
- Alive animals have been released
- Dead animals have been released
- Animals were already dead when caught
Specie
Photographs
Weight
Yes:_____
_____
_____
_____
Nº: _____
Nº: _____
Nº: _____
Size
Sex
No:_____
Figure 28. Form to use in fishing scientist surveys to collect general oceanographic data and
general condition data of by-catch species.
248
Teeth shape
Notched margin _____
Smoothed margin _____
Teeth photos
YES ____
NO ____
Other informations:
Stomach contents:
Yes: _____ No: _____
Embryo in the uterus:
(if possible conserve them frozen)
Yes: _____
No: _____
What kind of samples have you taken?
_______________________________________________________________________________
_______________________________________________________________________________
______
Photographs
Yes: _____ No: _____
Video
Yes: _____ No: _____
NOTES:
_______________________________________________________________________________
_____________________________________________________________________________
OBSERVER:
Name:
Address:
Figure 29. Form to use in fishing scientist surveys to collect data about teeth shape, stomach
contents, reproductive and other biological data.
249
Important samples to take and how to conserve them
Stomach contents
Intestine contents
Gonads
Muscle
Liver
Gill and gill-rakers1
Eye
Vertebra
Skin
Underkin fat
Spermatophores
Parasite
Utera
Alcohol 70%
***
***
Formalin 4%
*
*
***
***
Frozen
*
*
Bouin
*
***
***
***
***
***
***
***
***
***
***
*** Recommended method
* Alternative method
1: for the conservation of gills and gill-rakers it will be better to fix the sample with formalin 10% (formalin
and sea water) for a period of 12-24 h; then rinse the sample with fresh water and store it in alcohol 80º.
Figure 30. Form to use in fishing scientist surveys to collect biological samples.
250
TOT = total length (snout-posterior tip of caudal fin)
_____
FOR = fork length (snout-caudal posterior notch)
_____
PRC = precaudal length (snout-precaudal pit, upper origin)
_____
PD2 = pre-second dorsal length (snout-origin second dorsal fin)
_____
PD1 = pre-first dorsal length (snout-origin first dorsal fin)
_____
HDL = head length (snout-5th gill openings)
_____
PGI = prebranchial length (snout-1st gill openings)
_____
POB = preorbital length (snout-anterior eye margin)
_____
PP1 = prepectoral length (snout-origin of the pectoral fin)
_____
PP2 = prepelvic length (snout-origin pelvic fin)
_____
PAL = preanal length (snout-origin anal fin)
_____
Figure 31. Form to use in fishing scientist surveys to collect general length measurements in
sharks.
251
Head
EYL = eye length
EYH = eye height
POR = preoral length (snout-mouth)
PRN = prenarial length (snout-nostril)
ING = intergill length (1st-5 th gill)
_____
_____
_____
_____
_____
Pectoral fin
P1A = pectoral anterior margin (origin-apex)
P1L = pectoral length (origin-free rear tip)
P1P = pectoral posterior margin (apex-insertion)
P1H = pectoral height (apex-insertion)
P1B = pectoral base (origin-insertion)
P1I = pectoral inner margin (insertion-free rear tip)
_____
_____
_____
_____
_____
_____
Dorsal fin
D1A = first dorsal anterior margin (origin-apex)
D1B = first dorsal base (origin-insertion)
D1L = first dorsal length (origin-free rear tip)
D1I = first dorsal inner margin (insertion-free rear tip)
D1P = first dorsal posterior margin (free rear tip-apex)
D1H = first dorsal height (apex-middle point of the base)
_____
_____
_____
_____
_____
_____
Figure 32. Form to use in fishing scientist surveys to collect head and fin measurements.
252
Caudal fin
CDM = dorsal caudal margin (posterior margin of upper origin
of precaudal pit-posterior tip)
_____
CTR = terminal caudal margin
_____
CST = subterminal caudal margin
_____
CPU = upper postventral caudal margin (subterminal notch-posterior notch)
_____
CPL = lower postventral caudal margin (posterior notch-ventral tip)
_____
CPV = preventral caudal margin (ventral tip-posterior margin of lower
origin of precaudal pit)
_____
Clasper
CLI = clasper inner length
_____
CLO = clasper outer length
_____
Figure 33. Form to use in fishing scientist surveys to collect measurements of caudal fin and
claspers.
253
FLEET FILE
PORT:
MONTH:
YEAR:
VESSEL
LIST
AREA
HULL
REGISTRATION
NUMBER
SHEET GRT
Figure 34. Example of fleet data form.
254
HP
LENGT
YEAR
H
BASE
PORT
EQUIPMENT
Date:
Code of fishing gear:
Target species:
Vessel:
Main line
Length:
GRT:
HP:
Base port:
Total length (mn)
Unit
Length
Number of hooks
Number of hooks
Material
Gauge (Diameter)
Branch line
Length
Material
Stretch
Length
Gauge (Diameter)
Number of units
Number of hooks
Hooks
Type
Size
Dimensions (mm)
Hooks gaps
IMPORTANT: YOU MUST DRAW A GEAR SKETCH, NOTE ANY PARTICULAR CHANGE IN THE GEAR
OR TERMINOLOGY.
Figure 35. Example of form to collect gear characteristics in longline fisheries.
255
OBS/ TRIP ID
DATE LAND
(mm/yy)
NIMFS FISHERIES OBSERVER PROGRAM
GILLNET GEAR LOG
GEAR CODE
GEAR NUMBER(S)
AVERAGE NET:
USED?
NO
LENGTH ______FT
FLOATS
0___
HEIGHT ______FT
MESH COUNT
VERTICAL
HANGING RATIO
/
TIE DOWNS
SPACE(S)
BETWEEN
0___
NUMBER OF NETS
YES
MEASUREMENTS
Dist Between
1___
ft
Length ____·
1__ 2__
ft
COLOR
# OF NETS
MESH SIZE
in
0___
1___
Number ________
·
0___
1___
Width _________ft
·
TWINE SIZE___A /E
0___
1___
Lenght _________ft
·
# STRANDS ____
ANCHOR(S)
0___
1___
Weight _________Ibs
·
Number ________
Weight _________Ibs
(total)
Unknown
0___
Nylon
1___
Other
9___
A/E
·
DROPLINES
ADDTIONAL
WTS
NET MATERIAL
(CIRCLE
ONE)
A/E
A/E
A/E
A/E
OR
MESH SIZE RANGE
_____-_____ - _____-_____
SECURING
METHOD(S)
1___
Actual
1 ___
Estimated
2___
(diagram for reference only)
None
HIGHFLIER
FLOATLINE
2___
Ocean Bottom
MATERIAL
Unknown
Vessel / Ocean
3___
0_
Bottom
Floating (foam core)
4___
Vessel Only
1_
Twisted Polypropylene
2
Other
MM DETERRENT DEVICES USD?
9
LEADLINE WEIGHT
_______·______Ibs /
net
ACTIVE
0 __
Brand
_______________
1 __
PASSIVE
1 __
0 __
Water Line
···········································································································
·····················|
|
GEAR
NET
NET
|
Float Line
Number ________
Frequency
_______kHz
Space
|
|
End Line
|
_________|
Number ________
COMMENTS
Load Line
Page 1. Part___
loc
Unknow
00
Clear
White
02
Pink
Black
04
Green
Blue
06
Mukti-color
Red
08
Orange
Purple
10
Combination
98__ Other
····························
········
Set # _ _ _ _ _ _ _ _ _
mm
yy
set
Vessel: ___________________________ Date: In ____________ Out _______________
Hooks:_____________ Size:________ Gear: Bottom ;Float Target:__________________Stow-away: in_____ out____
Bait: ____________________________________________________________________________________________
Time
Air Tº
H2OTº
Location
Depth(ft)
Set
First Hook In: |___________ | __________ | ___________ | _________________________ | _____________________|
Last Hook In: |___________ | __________ | ___________ | _________________________ | _____________________|
Haul
First Hook Out:| __________| __________ | ___________ | Set Length: ________________
Last Hook Out:| __________| __________ | ___________ | Haulback Direction: B -> E , E-> B
Spec#
Species
A/D
Disp.
FL(cm)
TL(cm)
1.
2.
3.
4.
Figure 36. Form to collect sex data.
256
Misc.
Measure
Sex
Notes
Notes
SIZE DISTRIBUTIONS VERS SEX
Cruise:________________
CAST:
DEPTH:
Specie:_______________________________ CODE:_________________
RANGE:
1//2
MALES
I
II
III
1/2 cm
CODE:
SECTOR:
cm
DATE:
1//2
FEMALES
IV
I
PAGE Nº:
II
III
cm
INDET
IV
0
0
0
0,5
0,5
0,5
1
1
1
1,5
1,5
1,5
2
2
2
2,5
2,5
2,5
3
3
3
3,5
3,5
3,5
4
4
4
4,5
4,5
4,5
5
5
5
5,5
5,5
5,5
6
6
6
6,5
6,5
6,5
7
7
7
7,5
7,5
7,5
8
8
8
8,5
8,5
8,5
9
9
9
9,5
9,5
9,5
0
0
0
0,5
0,5
0,5
1
1
1
1,5
1,5
1,5
2
2
2
2,5
2,5
2,5
3
3
3
3,5
3,5
3,5
4
4
4
4,5
4,5
4,5
5
5
5
5,5
5,5
5,5
6
6
6
6,5
6,5
6,5
7
7
7
7,5
7,5
7,5
8
8
8
8,5
8,5
8,5
9
9
9
9,5
9,5
9,5
0
0
0
Number of specimen sampled:
Males=
Females=
Undetermined=
Total number estimated:
Males=
Females=
Undetermined=
Total weight of this specie:______________grs.
Total specimen number (M+F+I):________
Weight sampled:___________grs.
Conversion coefficient:
Initial size:________ Initial size:_________ Initial size:________
Final size: ________ Final size:_________ Final size _________
Figure 37. Form to collect size data.
257
1//2
cm
258
ANNEX III
INTERNATIONAL WORKSHOP ON MEDITERRANEAN
CARTILAGINOUS FISH WITH EMPHASIS ON SOUTHERN AND
EASTERN MEDITERRANEAN
14-16 October 2005 İstanbul/TURKEY
LIST OF PARTICIPANTS
SURNAME
NAME
INSTITUTION
NATION
E-MAIL
ALIÇLI
Zahit
İstanbul Univ.
Turkey
alilci@istanbul.edu.tr
ALTUĞ
Gülşen
İstanbul Univ.
Turkey
galtug@istanbul.edu.tr
ARAPI
Dritan
FDP
Albanıa
d_arapi@hotmail.com
BARANES
Albert-Avi
The inter
University
Institute for
Marine Sciences
Israel
avib@vms.huji.ac.il
BAŞUSTA
Nuri
Harran Univ.
Turkey
nbasusta@hotmail.com
BEN-ABDALLAH
Abdallah
EGA
Libya
abdallalıbfish@yahoo.com
BİZSEL
K.Can
Dokuz Eylül Univ.
Turkey
can.bizsel@deu.edu.tr
BRADAI
M.Nejmeddine
INSTM
Tunisia
mednejmeddine.bradai@instm.rnrt.tn
CEBRIAN
Daniel
UNEP/MAP
RAC/SPA
Tunisia
daniel.cebrian@rac-spa.org
CECAN
Haluk
Turkey
halukcecan@hotmail.com
CHATZISPYROU
Archontia
Univ. of Athens
Greece
a.chatzispyrou@mom.gr
ÇEKİÇ
Mustafa
Çukurova Univ.
Turkey
cekicm@cu.edu.tr
DAL
Tarık
Gaziosmanpaşa
Univ.
Turkey
tdal@gop.edu.tr
DOĞAN
Kadir
İstanbul Univ.
Turkey
kadogan@istanbul.edu.tr
DÖKMECİBAŞI
Banu
Greenpeace
Turkey
bdokmecı@diala.greenpeace.org
ERSEMİZ
Barış
İstanbul Univ.
Turkey
sailor669tr@yahoo.com
FERRETTI
Francesco
Dalhousıe Univ.
Italy
ferretti@dal.ca
FEYZİOĞLU
Muzaffer
KTU
Turkey
muzaffer@ktu.edu.tr
FİLİZ
Halit
Ege Univ.
Turkey
halit.filiz@ege.edu.tr
GARIBALDI
Fulvio
University of
Genova
Italy
garıbaldi.f@libero.it
259
GENÇ
Ercüment
MKÜ SUF
Turkey
egenc@mku.edu.tr
GOLANI
Daniel
The Hebrew
University of
Jerusalem
Israel
dgolani@cc.huji.ac.il
GÜÇLÜSOY
Harun
Dokuz Eylül Univ.
Turkey
harun.guclusoy@deu.edu.tr
HADJICHRISTOPHOROU
Myroula
Ministry of
Agricalture
Cyprus
andrecws@logos.cy.net
KARAKULAK
Saadet
TÜDAV
Turkey
karakul@istanbul.edu.trt
KESKİN
Çetin
İstanbul Univ.
Turkey
seahorse@istanbul.edu.tr
KUPUSOVIC
Esena
Meteorological
Instıtute
BosnıaHerzegovina
ekupusov@utic.net.ba
esena.kupusovic@heis.com.ba
MACIAS
David
IEO
Spain
david.macias@ma.ieo.es
MAVRIC
Borut
MBP National
Institute of
Biology
Slovenia
mavrıc@mbss.org
MOUMNI
Amina
INRH
Morocco
amoumni6@caramail.com
NADER
Manal
University of
Balamand
Lebanon
manal.nader@balamand.edu.lb
ÖZGÜR
Elif
İstanbul Univ.
Turkey
eozgur@istanbul.edu.tr
ÖZTÜRK
Bayram
İstanbul Univ.,
TÜDAV
Turkey
ozturkb@istanbul.edu.tr
tudav@superonline.com
PAYASLIOĞLU
Mutlu
Turkey
mutlup@yahoo.com
SAAD
Adib
Tishreen Univ.
Syria
adibsaad@scs-net.org
SCHEMBRI
Titian
University of
Malta
Malta
titianpaul@camline.net.mt
schembrinu@yahoo.com
SERENA
Fabrizio
ARPAT
Italy
f.serena@arpat.toscana.it
SERET
Bernard
IRD MNHN
France
seret@mnhn.fr
SOLDO
Alen
IOR
Croatıa
soldo@izor.hr
SÜTÇÜOĞLU
Merve Pelin
İstanbul Univ.
Turkey
mervepelin@yahoo.com
TIRAŞIN
E. Mümtaz
Dokuz Eylül Univ.
Turkey
mumtaz.tirasin@deu.edu.tr
TONAY
Arda
TÜDAV
Turkey
atonay@istanbul.edu.tr
TURAN
Cemal
M.K.U.
Turkey
cturan@mku.edu.tr
TÜRKER ÇAKIR
Dilek
Balıkesir Univ.
Turkey
dilektürker@hotmail.com
YARDIMCI
Cumhur
İstanbul Univ.
Turkey
yardimci@istanbul.edu.tr
YELDAN
Hacer
Çukurova Univ.
Turkey
hacyel@yahoo.com
YOKEŞ
Baki
Boğaziçi Univ.
Turkey
yokesmeh@boun.edu.tr
260
261
262
Ercument Genc