Not just
Shark Pictures:
Elasmodiver contains photos of sharks, skates, rays, and chimaera's
from around the world. Elasmodiver began as a simple web based
shark
field guide
to help divers find the best places to encounter the different
species of sharks and rays that live in shallow water but it has
slowly evolved into a much larger project containing information on
all aspects of shark diving and shark photography.
There are now
more than 10,000 shark pictures and sections on shark
evolution, biology, and conservation. There is a large library of
reviewed shark books, a constantly updated shark taxonomy page, a
monster list of shark links, and deeper in the site there are
numerous articles and stories about shark encounters. Elasmodiver is
now so difficult to check for updates, that new information and
pictures are listed on an Elasmodiver Updates Page that can be
accessed here:
Identification:
grey/brown body with subtle mottling. Ventral surface marginally lighter than
dorsal surface. Skin quite smooth and covered in mucus. Snout more broadly
rounded than other gulper sharks. First dorsal fin length about twice
height with long free rear tip. Dorsal fins dusky on
leading edges. First dorsal spine length about 1/3rd length of leading edge of
dorsal fin. Second dorsal spine slightly longer. Thin white margins on posterior
edges of dorsal and caudal fins (not always visible). Upper caudal lobe deeply
notched. Lower caudal lobe moderately long but weakly defined (indistinct
posterior notch). Pectoral and anal fins with long free rear tips. Eyes
large and green with gold rims. Lower teeth square cut. Upper teeth wide with
single narrow point.
Size: Maximum
length 160cm male, 145cm female. size at birth 30-42cm.
Habitat:
Continental shelves and slopes from 50-1440m but rarely shallower than 200m. In
the Bahamas, gulper sharks are more frequently caught around monumentation than
on featureless substrate.
Abundance and distribution:
A wide ranging species. Eastern Atlantic - France to West and possibly South
Africa (including the Mediterranean Sea). Western Atlantic - Gulf of Mexico to
northern South America. Indian Ocean - Madagascar, Sudan and Western Australia.
And Western Pacific south of Japan. Not recorded in the Eastern Pacific.
IUCN Red List
Status: Vulnerable. Believed to have the lowest reproductive potential of
all elasmobranch species; its reproductive biology is characterized by a late
onset of maturity (12 to 16 years in females), only one pup per litter and a
two-year gestation period with occasional resting periods. This makes it
extremely vulnerable to overexploitation and population depletion. Despite a
lack of data for certain regions within its geographic range, this species is
globally assessed as Vulnerable on the basis of its limiting life history traits
and the global increase in unmanaged fishing effort to exploit deeper waters.
Heavily fished and
caught as bycatch in the Northeast Atlantic, the Northwest Pacific and other
regions. Targeted for liver oil and meat.
Behavior:
Not known.
Diet: small bony fishes,
squid and crustaceans.
Reproduction:
Ovoviviparous. One pup per litter. Gestation period 2 years with resting periods
inbetween. Maturity probably occurs around 60-80cm.
Observations: Mortality
among captured specimens is quite high suggesting that gulper sharks do not
respond well to temperature changes and stress.
Photographs:
Cape Eleuthera, Bahamas. Images captured during a deep shark survey conducted by
Edd Brooks of the Cape Eleuthera Institute.
Similar species:
Because the Common Gulper Shark is a broad ranging species, it overlaps with
many other species of gulpers. In the Bahamas it is found with
Taiwan gulper
sharks which are slightly thinner, have a more depressed head and no discernable
caudal posterior notch.
Reaction to divers:
Not encountered by divers.
Diving logistics:
Not applicable.
References:
Citation:
Guallart, J., Serena, F., Mancusi, C., Casper, B.M., Burgess, G.H., Ebert, D.A.,
Clarke, M. & Stenberg, C. 2006. Centrophorus granulosus. In: IUCN 2011. IUCN Red
List of Threatened Species. Version 2011.1. <www.iucnredlist.org>. Downloaded on
19 October 2011.