Carcharhinus obscurus (Northwest and Western Central Atlantic subpopulation)

Taxonomy

Assessment Information

Geographic Range

Population

Habitat and Ecology

Threats

Bibliography

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Taxonomy [top]

Kingdom	Phylum	Class	Order	Family
ANIMALIA	CHORDATA	CHONDRICHTHYES	CARCHARHINIFORMES	CARCHARHINIDAE

Scientific Name:

Carcharhinus obscurus (Northwest and Western Central Atlantic subpopulation)

Species Authority:

(Lesueur, 1818)

Common Name/s:

English

–

Dusky Shark

Assessment Information [top]

Red List Category & Criteria:	Vulnerable A1abd ver 2.3
Year Published:	2000
Annotations:	Needs updating
Assessor/s:	Camhi, M., Musick, J.A. & Simpfendorfer, C.
Reviewer/s:	Musick, J.A. & Fowler, S. (Shark Red List Authority)
Contributor/s:
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.

Geographic Range [top]

Countries:	Native: Mexico; United States
FAO Marine Fishing Areas:	Native: Atlantic – northwest; Atlantic – western central
Range Map:	Click here to open the map viewer and explore range.

Population [top]

Population Trend:	Decreasing

Population Trend:

Decreasing

Habitat and Ecology [top]

Habitat and Ecology:	C. obscurus is a coastal-pelagic species found inshore and offshore in warm-temperate and tropical waters of the continental and insular shelves and the oceanic waters adjacent to them. The species ranges from close inshore in the surf zone to well out to sea and from the surface to 400 m depth. It does not prefer areas with reduced salinities and tends to avoid estuaries. Adult dusky sharks are often seen offshore and commonly follow ships. This shark is strongly migratory in temperate and subtropical areas in the eastern north Pacific and western north Atlantic, moving north during the warmer months of summer and retreating south when the water cools. Dusky sharks eat a wide variety of reef, bottom, and pelagic bony fishes, as well as other elasmobranchs, crustaceans, octopi, cuttlefish, squid, starfish, barnacles, bryozoans, whale meat, and occasional garbage (Compagno 1984).
Systems:	Marine

Habitat and Ecology:

C. obscurus is a coastal-pelagic species found inshore and offshore in warm-temperate and tropical waters of the continental and insular shelves and the oceanic waters adjacent to them. The species ranges from close inshore in the surf zone to well out to sea and from the surface to 400 m depth. It does not prefer areas with reduced salinities and tends to avoid estuaries. Adult dusky sharks are often seen offshore and commonly follow ships. This shark is strongly migratory in temperate and subtropical areas in the eastern north Pacific and western north Atlantic, moving north during the warmer months of summer and retreating south when the water cools. Dusky sharks eat a wide variety of reef, bottom, and pelagic bony fishes, as well as other elasmobranchs, crustaceans, octopi, cuttlefish, squid, starfish, barnacles, bryozoans, whale meat, and occasional garbage (Compagno 1984).

Systems:

Marine

Threats [top]

Major Threat(s):	The species has a very slow growth rate, with late maturation, long gestation period, and small litters. Its very low intrinsic rate of increase makes it particularly vulnerable to depletion by man. The species is taken with other more productive sharks in mixed species fisheries, and has a high mortality rate when taken as bycatch.

Major Threat(s):

The species has a very slow growth rate, with late maturation, long gestation period, and small litters. Its very low intrinsic rate of increase makes it particularly vulnerable to depletion by man. The species is taken with other more productive sharks in mixed species fisheries, and has a high mortality rate when taken as bycatch.

Bibliography [top]

	Compagno, L.J.V. 1984. FAO species catalogue. Vol. 4. Sharks of the world. An annotated and illustrated catalogue of shark species known to date. FAO Fish. Synop. No. 125, vol. 4. Hilton-Taylor, C. 2000. 2000 IUCN Red List of Threatened Species. IUCN, Gland, Switzerland and Cambridge, UK. IUCN SSC Shark Specialist Group. Specialist Group website. Available at: http://www.iucnssg.org/. Shark Specialist Group. 2000. IUCN Shark Specialist Group Red List Assessments, 2000 (unpublished report).

Compagno, L.J.V. 1984. FAO species catalogue. Vol. 4. Sharks of the world. An annotated and illustrated catalogue of shark species known to date. FAO Fish. Synop. No. 125, vol. 4.

Hilton-Taylor, C. 2000. 2000 IUCN Red List of Threatened Species. IUCN, Gland, Switzerland and Cambridge, UK.

IUCN SSC Shark Specialist Group. Specialist Group website. Available at: http://www.iucnssg.org/.

Shark Specialist Group. 2000. IUCN Shark Specialist Group Red List Assessments, 2000 (unpublished report).

Citation:	Camhi, M., Musick, J.A. & Simpfendorfer, C. 2000. Carcharhinus obscurus (Northwest and Western Central Atlantic subpopulation). In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <www.iucnredlist.org>. Downloaded on 20 June 2013.
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