Angular rough shark  (Oxynotus centrina)

The angular rough shark is classified as Vulnerable (VU) on the IUCN Red List (1).

A rare and little-known species, the angular rough shark (Oxynotus centrina) is suitably named for its pointed head and fins, and the rough teeth-like scales, known as ‘denticles’, which cover its body. The angular rough shark has a broad, flattened head, a short, blunt nose and two tall, sail-like dorsal fins (3) (4).

The upperparts of the angular rough shark’s body are a marbled pattern of greyish-brown, with dark blotches on the head and sides. A number of lighter streaks decorate the head (3) (4).

The angular rough shark has extremely large, oval or crescent-shaped spiracles, situated beside the eyes (3) (4) (5).

The angular rough shark occurs in the eastern Atlantic Ocean and the Mediterranean Sea (1). It may also occur off the coast of East Africa, near Mozambique, but this is debated (3).

The angular rough shark is typically found close to the sea bed at depths between 60 and 660 metres. It is most commonly associated with muddy or coralline substrates (1) (4).

The diet of the angular rough shark is believed to consist of polychaete worms, crustaceans and molluscs (4), which it apparently feeds on using a suction mechanism (6). It typically moves by gliding along the seabed, frequently pausing to hover over the sandy or muddy surface (7).

The angular rough shark is an ovoviviparous species, with females producing litters of 10 to 12 pups each year. These pups measure 21 to 24 centimetres at birth (4). Female angular rough sharks become sexually mature when they reach around 65 centimetres in length, while males reach maturity at around 60 centimetres (2).

Deep water fisheries in the Mediterranean and the northeast Atlantic are threatening the angular rough shark, which, although not specifically targeted by fishermen, is often caught as bycatch (1) (3). When captured, the shark may be discarded (4), or used for oil, food for fish farms or food for humans (3).

Bottom trawling in the Mediterranean Sea has become more efficient over the last 50 years, resulting in the angular rough shark now being extremely rare. In the northeast Atlantic, little information is available on angular rough shark numbers, but as deepwater fisheries have expanded in both range and effort, it is likely that the angular rough shark has declined in this region too (1).

There are currently no management plans in place for the conservation of the angular rough shark (4), but a number of conservation measures have been recommended.

Bycatch of the angular rough shark needs to be monitored, to gain a better picture of its population numbers and the impact fisheries are having on this species. A more thorough knowledge of the angular rough shark’s ecology and distribution will also help inform any future conservation measures (1).

Ultimately, sustainable management plans that ensure the conservation of all sharks in the Mediterranean need to be developed and implemented (1). As more than 40 percent of shark and ray species in the Mediterranean are now considered to be threatened with extinction, the need for conservation action is considered by many to be urgent (8).  

Discover more about shark conservation:

• Shark Trust:
  http://www.sharktrust.org/
• Shark Alliance:
  http://www.sharkalliance.org/
• Bite-Back – Shark and Marine Conservation:
  http://www.bite-back.com/