Shark of the week: angular roughshark

Did you know that there are sharks looking a little like sailboats? One of them is the angular roughshark (Oxynotus centrina).

All roughsharks have a rough, prickly skin (hence their name), spines in front of their large dorsal fins and bioluminescent organs. They are ovoviviparous (that means the embryos develop inside eggs, but remain in the mother’s body, hatch and are born after).

Described first in 1758 by Carl von Linné, the Oxynotus centrina is a deepwater, bottom dwelling shark living at the west coast of Europe and Africa, and in the Mediterranean and Adriatic Sea. It has a very large spiracle behind each eye and ridges over its eyes covered with enlarged denticles (unlike all other species of roughsharks).

Once a year 10 to 12 pups less than 9.8 in – 25 cm- in size are born. Most reach 3.3 ft -1 m- in length (rarely 4.9 ft -1.5 m-). Angular roughsharks can feed on worms, crustaceans and mollusks, but due to their small but highly specialised mouths they seem to be destined to feed on egg cases (like this admittedly small study suggests).

Angular roughsharks aren’t commercially fished (they are even thought to bring bad luck to fisherman if caught and kept). Sadly, when released, they have only a small chance of survival. Due to the increase in deepwater fishing activities, angular roughsharks (as bycatch) are considered vulnerable by the IUCN. Their numbers decrease, and, despite up to 1997 abundant there, “this species was absent in a recent and intensive study of the deepwater longline fishery for sharks off the Canary Islands”. And although there is a ban on bottom trawling below depths of 3,300 ft -1,000 m- in the Mediterranean since 2005,  angular roughsharks aren’t protected, since it doesn’t apply to their depth range (up to 2,170 ft -660 m).

Sources: here and here