
Thursday 15 February
The World's Favourite Unloved Species 2018 - the Galapagos Racer
Kingdom | Animalia |
Phylum | Chordata |
Class | Chondrichthyes |
Order | Squaliformes |
Family | Centrophoridae |
Genus | Centrophorus (1) |
Found lurking in deep waters, the gulper shark (Centrophorus granulosus) is a long and slender fish with a long snout and large, green eyes. Like all dogfish, the gulper shark has two dorsal fins bearing long, grooved spines. The second dorsal fin is smaller than the first, and there is no anal fin (2) (3).
The upperparts of the gulper shark are olive-grey to grey-brown, and its underside is lighter. The adult has no obvious markings. The juvenile gulper shark is lighter than the adult, and has white-tipped dorsal and caudal fins (2) (3).
The gulper shark inhabits deep waters, living in schools and predating on small fish and on invertebrates such as hake and cephalopods (1) (2).
This species can live for more than 30 years, with the female gulper shark reaching maturity between 12 and 16 years, and the male between 7 and 8 years (1).
The gulper shark has an exceptionally long gestation period of two years. The unfertilised egg cell of the gulper shark reaches one of the largest cellular sizes described for any animal, weighing between 143 and 370 grams. The gulper shark is ovoviviparous, producing eggs which hatch inside the females’ body. The components of the egg and any unfertilised eggs are used to nourish the developing pup, which is then born live (4).
A long gestation period, one pup per litter, late maturity and occasional resting periods between pregnancies mean that the gulper shark has an extremely low reproductive rate, with probably has the lowest reproductive potential of any elasmobranch (1).
A demersal species, the gulper shark is found lurking on or near the substrate on upper slopes and along continental shelves at depths of up to 1,400 metres. Juvenile gulper sharks are thought to live in deeper water than the adults (1).
The gulper shark is classified as Vulnerable (VU) on the IUCN Red List (1).
Overfishing poses the main threat to the gulper shark. This species is heavily fished for its liver oil and meat. Even with moderate fishing levels, the low reproductive rate of the gulper shark means that population numbers may be severely depleted if not properly managed (1).
Globally, there is a general trend for fisheries to exploit deeper fishing grounds using methods such as bottom trawling and bottom longlines. Population levels of the gulper shark have decreased by 80 to 95 percent in the northeast Atlantic since 1990 (1). In the Mediterranean, gulper shark aggregations are targeted by fisheries using longlines and gillnets (1) (5). The gulper shark is also caught as bycatch in bottom trawls and long line fisheries that target other species, further depleting its population levels (1).
Currently in the northwest and southeast Atlantic there are no specific conservation measures in place for the gulper shark. In 2005, the General Fisheries Commission for the Mediterranean (GFCM) banned fishing at depths below 1,000 metres in the Mediterranean; however, the gulper shark can often be found above this depth (1). The International Council for the Exploration of the Sea (ICES) has also recommended that there should be no deepwater fisheries of sharks (5).
Futher research is also required into the biology, taxonomy and populatons of the guler shark, and the fishing pressures on this species need to be monitored (1).
More information on the gulper shark:
This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:
arkive@wildscreen.org.uk
Image credit
© Andy Murch / Elasmodiver.com
Elasmodiver.com
andymurch1@gmail.com
http://www.elasmodiver.com
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Thursday 15 February
The World's Favourite Unloved Species 2018 - the Galapagos Racer
Thursday 01 February
Thursday 01 February