FAO Species Identification Guide for Fishery Purposes Western

1344 Sharks
Carcharhinus obscurus (LeSueur, 1818)
Frequent synonyms / misidentifications: Carcharhinus iranzae Fourmanoir, 1961 / None.
FAO names: En - Dusky shark; Fr - Requin sombre (= Réquiem de sable, Area 31); Sp - Tiburón arenero.
Diagnostic characters: Body slender to moderately stout.
Snout rounded and short, its length equal to or less than
mouth width and greater than or about equal to internasal
space; labial furrows short; anterior nasal flaps
rudimentary; upper teeth broadly triangular, erectto
moderately oblique, anterior teeth with strongly serrated
broad cusps not delimited from the bases; lower teeth with
low, narrow, serrated cusps; gill slits relatively short. First
dorsal fin relatively low, with a broadly arched anterior
margin and a narrowly rounded or pointed apex, its origin
about over free rear tips of pectoral fins; second
dorsal fin also moderately low, with a nearly straight
ventral view
of head
upper and lower
tooth near centre
posterior margin, an inner margin nearly or quite twice the fin height, and its origin about over that of
anal fin; pectoral fins falcate and apically pointed. A low interdorsal ridge present. Colour: blue-grey,
lead-grey above, white below; tips of pectoral and pelvic fins, as well as lower lobe of caudal fin and dorsal
fins often dusky in young, plain in adults.
Size: Maximum total length about 3.64 m; matures at about 2.8 m; size at birth about 70 cm to 1 m.
Habitat, biology, and fisheries: A semi-pelagic shark occurring from inshore waters to the outer
continental shelf. Viviparous, number of embryos 6 to 14. Feeds chiefly on fishes, including scombrids,
clupeids, serranids, trichiurids, bluefish, wrasses, anchovies, grunts, barracudas, sharks and rays, also
squids, octopi, gastropods, shrimps, crabs, and carrion. Reported to be dangerous to humans, but attacks
in the area are unverified. Regularly caught with longlines and probably gill nets, also hook-and-line and
set bottom nets; utilized fresh, dried-salted, frozen and smoked for human consumption; hides used for
leather; fins for shark-fin soup; liver oil extracted for vitamins.
Distribution: Wide-ranging,
but with a patchy distribution
in tropical and subtropical
seas; in the western Central
Pacific more confined to the
marginal parts of the area
(Japan, China, Viet Nam,
Australia).