Atlantic Sharpnose Shark


Atlantic sharpnose shark - Rhizoprionodon terraenovae

*Information from FAO Species Identification Guide Western Central Atlantic*

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Size
Maximum total length at least 110 cm, common to 90 cm; size at birth about 29 to 37 cm; males maturing between 65 and 80 cm and females at 85 to 90 cm.
Diagnostic characters

Body slender and fusiform. Eyes large, internal nictitating lower eyelids present. Snout long and depressed, preoral length 1.5 to 1.7 times internarial width, tip narrowly rounded; labial folds well developed, the upper pair about equal in length to eye diameter and ending well behind eyes. Teeth strongly oblique, their edges smooth to finely serrated in adults; anteroposterior tooth row counts 11 to 13/12 to 13 on each side, total tooth row counts 24 to 27/24 to 27. Spiracles absent; gill slits short, height of third gill slit about 2.2 to 2.5% of total length; gill arches without papillae. First dorsal fin moderate-sized, height 7.4 to 9.2% of total length, with a narrowly rounded apex, an origin opposite the pectoral-fin inner margins, and the midlength of its base slightly closer to the pectoral fin insertions than the pelvic-fin origins; second dorsal fin low and much smaller than first dorsal fin, height 1.9 to 2.5% of total length; second dorsal fin with a shallowly concave posterior margin, an origin opposite the space between the midpoint of the anal-fin base and the anal-fin insertion, an attenuated free rear tip, and an inner margin over twice the fin height; anal fin with a shallowly concave posterior margin and long paired preanal ridges; pectoral fins relatively short, broad and not falcate, extending to below midpoint of first dorsal-fin base when adpressed.A low interdorsal ridge present between dorsal fins; no keels on caudal peduncle. Precaudal vertebral centra 56 to 66, usually below 66, and equal or less in number than caudal centra, total vertebral centra 126 to 144.Colour: grey or grey-brown above, large specimens with small light spots on the dorsal surface, white below; pectoral fins with white margins, dorsal fins with dusky tips.

Habitat, biology, and fisheries

Inhabits waters from the intertidal to possibly 280 m deep, but usually in water less than 10mdeep.Often occurring in the surf zone off sandy beaches, and in enclosed bays, sounds, harbors, estuaries, and river mouths. Tolerates reduced salinities but does not penetrate far into fresh water. A common to abundant shark where it occurs. Migratory, moving inshore in summer and offshore in winter.Number of young 1 to 7 per litter.Feeds primarily on small bony fishes, shrimps, crabs, worms, and molluscs.Fished wherever it occurs, caught commercially in Mexico. Caught in gill nets and targeted by sports anglers using rodand- reel;and a major bycatch of the USA shrimp trawling fishery. Despite heavy fishing pressure numbers in the Gulf of Mexico seem to be stable.

Distribution

Western North Atlantic: Canada (New Brunswick), Canada, USA (New England to Florida and the Gulf of Mexico), Mexico, and Honduras.