Carcharhinus obscurus (Northwest and Western Central Atlantic subpopulation)
|Scientific Name:||Carcharhinus obscurus (Northwest and Western Central Atlantic subpopulation)|
|Red List Category & Criteria:||Vulnerable A1abd ver 2.3|
|Assessor(s):||Camhi, M., Musick, J.A. & Simpfendorfer, C.|
|Reviewer(s):||Musick, J.A. & Fowler, S. (Shark Red List Authority)|
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.
Native:Mexico; United States
|FAO Marine Fishing Areas:|
Atlantic – western central; Atlantic – northwest
|Range Map:||Click here to open the map viewer and explore range.|
|Current Population Trend:||Decreasing|
|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).|
|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.|
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 Fisheries Synopsis No. 125, Volume 4, Part 1.
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). The IUCN Red List of Threatened Species 2000: e.T39376A10219868.Downloaded on 19 April 2018.|