Carcharhinus obscurus

Taxonomy

Assessment Information

Geographic Range

Population

Habitat and Ecology

Threats

Conservation Actions

Taxonomy [top]

Kingdom	Phylum	Class	Order	Family
ANIMALIA	CHORDATA	CHONDRICHTHYES	CARCHARHINIFORMES	CARCHARHINIDAE

Scientific Name:

Carcharhinus obscurus

Species Authority

(Lesueur, 1818)

Common Name/s:

English

–

Dusky Shark

Assessment Information [top]

Red List Category & Criteria:

Lower Risk/near threatened ver 2.3

Year Assessed:

2000

Assessor/s

Shark Specialist Group

Evaluator/s:

Musick, J.A. & Fowler, S. (Shark Red List Authority)

Justification:
A large, wide-ranging, coastal and pelagic warm water species. Among the slowest-growing, latest-maturing of known sharks, bearing small litters after a long gestation, and one of the most vulnerable of vertebrates to depletion by man because of its very low intrinsic rate of increase. Difficult to manage or protect because it is taken with other more productive sharks in mixed species fisheries, and has a high mortality rate when taken as bycatch. Catch rates for dusky shark in the western Atlantic have declined markedly. The population in the northwestern Atlantic and Gulf of Mexico is now probably at 15-20% of its mid-1970s abundance. In other regions the impact of fishing has not been as great, but still requires close monitoring.

History:

1996

–

Endangered (Baillie and Groombridge 1996)

Geographic Range [top]

Range Description:	This species has been recorded in the western Atlantic from Southern Massachusetts south to the northern Gulf of Mexico, and from Nicaragua to southern Brazil; various locations in the eastern Atlantic; the western Indian Ocean around South Africa, Mozambique, and Madagascar; eastern Indian Ocean off Western Australia; the western Pacific off the coasts of Japan, China, Viet Nam, and Queensland and New South Wales, Australia; and the eastern Pacific from Southern California to the Gulf of California, Revillagigedo Islands, and possibly Chile.
Countries:	Native: Algeria; Australia; Bahamas; Brazil; Cape Verde; China; Colombia; Cuba; Djibouti; Fiji; French Guiana; Gambia; Guinea; Guinea-Bissau; Guyana; Hong Kong; Israel; Japan; Macao; Madagascar; Mexico (Revillagigedo Is.); Morocco; Mozambique; New Caledonia; Nicaragua; Portugal (Madeira); Senegal; Sierra Leone; South Africa; Spain (Canary Is.); Suriname; Taiwan, Province of China; Trinidad and Tobago; Tuvalu; United States (Florida, Georgia, Louisiana, Maryland, Massachusetts, Mississippi, New Jersey, North Carolina, Rhode Island, South Carolina); Venezuela; Viet Nam
FAO Marine Fishing Areas:	Native: Atlantic – western central; Atlantic – northwest; Atlantic – southeast; Atlantic – southwest; Atlantic – eastern central; Indian Ocean – western; Indian Ocean – eastern; Mediterranean and Black Sea; Pacific – western central; Pacific – southwest; Pacific – eastern central; Pacific – northwest; Pacific – southeast

Population [top]

Population Trend:	Decreasing

Population Trend:

Decreasing

Habitat and Ecology [top]

Habitat and Ecology:	C. obscurus is a coastal-pelagic species of inshore and offshore warm-temperate and tropical waters. It occurs on continental and insular shelves and the oceanic waters adjacent to them, ranging from close inshore in the surf zone to well out to sea and from the surface to 400 m depth. It avoids estuaries and other reduced salinity areas. Adult dusky sharks are often seen offshore and are known to follow ships. In temperate and subtropical areas the species is migratory, moving north during the warmer summer months and retreating south when water temperatures drop. Diet includes a variety of reef, bottom, and pelagic bony fishes, along with other shark species, rays, crustaceans, cephalapods, barnacles, and whale meat.
Systems:	Marine

Habitat and Ecology:

C. obscurus is a coastal-pelagic species of inshore and offshore warm-temperate and tropical waters. It occurs on continental and insular shelves and the oceanic waters adjacent to them, ranging from close inshore in the surf zone to well out to sea and from the surface to 400 m depth. It avoids estuaries and other reduced salinity areas. Adult dusky sharks are often seen offshore and are known to follow ships. In temperate and subtropical areas the species is migratory, moving north during the warmer summer months and retreating south when water temperatures drop. Diet includes a variety of reef, bottom, and pelagic bony fishes, along with other shark species, rays, crustaceans, cephalapods, barnacles, and whale meat.

Systems:

Marine

Threats [top]

Major Threat(s):	A combination of slow growth rates, late maturation, and long gestation period result in this species having a very low intrinsic rate of increase. This increases the shark's vulnerability to fishery activities. Off Natal, South Africa, an efficient shark gillnetting program set up to protect bathing beaches has apparently resulted in an increase in juvenile dusky sharks there.

Major Threat(s):

A combination of slow growth rates, late maturation, and long gestation period result in this species having a very low intrinsic rate of increase. This increases the shark's vulnerability to fishery activities. Off Natal, South Africa, an efficient shark gillnetting program set up to protect bathing beaches has apparently resulted in an increase in juvenile dusky sharks there.

Conservation Actions [top]

Citation:	Shark Specialist Group 2000. Carcharhinus obscurus. In: IUCN 2008. 2008 IUCN Red List of Threatened Species. <www.iucnredlist.org>. Downloaded on 23 November 2008.
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