Angel shark  (Squatina squatina)

Classified as Critically Endangered (CR) on the IUCN Red List (1).

With its exceptionally flat body and large pectoral fins, the angel shark resembles a large ray more than a shark. Its skin is grey to reddish or greenish-brown, scattered with small white spots and blackish dots. Young angel sharks may also have white net-like markings and large, dark blotches, whilst adults are plainer (3). The dorsal fins have a dark leading edge and a pale trailing edge. It possesses simple, whisker-like projections near the nostrils, (nasal barbels), which are used to taste and feel (3). Large, round eyes with vertical slit pupils provide good all-round vision, enabling the angel shark to be an efficient ambush predator (4).

Occurs in the north-eastern Atlantic. Historically, its range extended from Norway to Mauritania, the Canary Islands, Mediterranean and Black Sea. However it has now vanished from some areas, and is uncommon in the remainder of its range (1) (3).

The angel shark occurs in temperate waters, over mud or sand, from coasts and estuaries to depths of over 150 metres (2).

The critically endangered angel shark is nocturnal, and spends its days lying buried in the mud or sand with just its eyes protruding. From this position it can ambush its prey, and will burst out at a startling speed to engulf flatfishes, skates, crustaceans or molluscs. At night, it swims strongly off the bottom. In the northern parts of its range the angel shark is seasonally migratory, and moves northwards during the summer (2).

The angel shark is ovoviviparous, a method of reproduction in which the young develop within eggs that remain inside the body until they hatch. Gestation lasts eight to ten months, and females give birth to pups that are 24 to 30 centimetres long. The number of pups in each litter varies from 7 to 25 pups, with larger females having larger litters (3). Whilst the small size of angel sharks means that they are not a particularly dangerous species, their strong jaws and sharp, needle-like teeth can inflict a painful bite on a provoking human (5).

The angel shark is not particularly sought after by fisheries, and since 1989 catches have only been reported from Tunisia. The small numbers caught are utilised for human consumption, and possibly also used for oil and fishmeal (5). A more widespread, potential threat is the capture of this species as by-catch (5). As they lie on the bottom, angel sharks are particularly vulnerable to by-catch in trawl fisheries, an activity that has increased in the last 50 years. As a result, numbers of angel sharks have declined dramatically, and have even been declared extinct in the North Sea (1).

All Squatina species are protected within three Balearic Islands marine reserves, where fishing for these species is forbidden (1). The status of the angel shark in many parts of its range is unknown (1), and the impact of fisheries is unclear (5), and thus research is required and conservation measures urgently need to be implemented (1), to assure the conservation of this unusual and distinctive shark.

For further information on shark species and their conservation see:

• Save Our Seas Foundation:
  http://www.saveourseas.com/
• Project Aware:
  www.projectaware.org
• The Shark Trust:
  www.sharktrust.org

• By-catch: in the fishing industry, the part of the catch made up of non-target species.
• Crustaceans: diverse group of arthropods (a phylum of animals with jointed limbs and a hard chitinous exoskeleton) characterised by the possession of two pairs of antennae, one pair of mandibles (parts of the mouthparts used for handling and processing food) and two pairs of maxillae (appendages used in eating, which are located behind the mandibles). Includes crabs, lobsters, shrimps, slaters, woodlice and barnacles.
• Dorsal fins: the unpaired fins found on the back of the body of fish, or the raised structure on the back of most cetaceans.
• Molluscs: a diverse group of invertebrates, mainly marine, that have one or all of the following; a horny, toothed ribbon in the mouth (the radula), a shell covering the upper surface of the body, and a mantle or mantle cavity with a type of gill. Includes snails, slugs, shellfish, octopuses and squid.
• Nocturnal: active at night.
• Pectoral fins: on fish, the pair of fins that are found one on each side of the body just behind the gills. They are generally used for balancing and braking.

1. IUCN Red List (June, 2007)
   http://www.iucnredlist.org
2. 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. Part 1: Hexanchiformes to Lamniformes.Food and Agriculture Organization of the United Nations, Rome.
3. Compagno, L.J.V., Fowler, S. and Dando, M. (2005) Sharks of the World.Harper Collins, London.
4. Gill, A. (2005) Look into our eyes. BBC Wildlife, 23: 16 - 17.
5. FAO Species Fact Sheet (July, 2007)
   http://www.fao.org/fi/website/FIRetrieveAction.do?dom=species&fid=2046