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Carcharhinus obscurus

(Brown Common Gray Shark)

Overview

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Found in coastal and offshore waters but not oceanic [1]. Adults are commonly found at depths of 200-400 m , young in shallower waters[2]. A seasonal migratory species over parts of its range [3]. Feeds on bottom and pelagic bony fish, sharks , skates , rays , cephalopods , gastropods , crustaceans, sometimes mammalian carrion and inorganic objects[1]. Viviparous [4]. Large adults are potentially dangerous[5][3]. Utilized fresh, dried-salted, frozen and smoked for human consumption ; hides for leather ; fins for sharks-fin soup ; and liver oil extracted for vitamins[6].

Common Names

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Click on the language to view common names.

Common Names in Afrikaans:

Donkerhaai

Common Names in Austronesian (Other):

Metel

Common Names in Carolinian:

Metel

Common Names in Catalan:

Tauró Fosc, Taur Fosc

Common Names in Danish:

Mørkhaj, Mrkhaj

Common Names in Dutch:

Schemerhaai

Common Names in English:

Bay Shark, Bay-Shark, Black Whaler, Bronze Shark Whaler, Bronze Whaler, Brown Common Gray Shark, Brown Dusky Shark, Brown Shark, Common Whaler, Dusky Ground Shark, Dusky Shark, Dusky Whaler, Requin Obscur, Shark, Shovelnose

Common Names in Finnish:

Sumuhai

Common Names in Fon:

Ehouatagbo

Common Names in Fon Gbe:

Ehouatagbo

Common Names in French:

Rechin, Requiem De Sable, Requin, Requin De Sable, Requin Sombre

Common Names in German:

Blauhai, Dunkelhai, Grauhai, Sandbankhai

Common Names in Greek:

Καρχαρίνος σκοτεινόχρωμος, Καρχαρίνος σκοτεινόχρωμος, Karcharynos Skotinochromos

Common Names in Greek, Modern (1453):

Καρχαρίνος σκοτεινόχρωμος, Karcharynos Skotinochromos, Lamia

Common Names in Italian:

Squalo Grigio, Squalo Scuro

Common Names in Japanese:

Dotabuka

Common Names in Mandarin Chinese:

大沙, 暗體真鯊, 灰真鯊, 灰色白眼鮫, 灰真鯊, 灰真鲨, 灰色白眼鮫, 灰色白眼鲛, 大沙, 暗體真鯊, 暗体真鲨

Common Names in Polish:

Zarlacz Ciemnoskóry, Zarlacz Ciemnoskry

Common Names in Portuguese:

Cação, Cação Fidalgo, Cao, Cao Fidalgo, Estrela, Faqueta, Fidalgo, Lobo, Marracho Areneiro, Marracho-Faqueta, Tubaro-Faqueta, Tubarão-Faqueta

Common Names in Spanish:

Arenero, Cazón, Cazn, Jaqueta, Jaquetón, Jaquetn, Lamia, Lobo, Melgacho, Tiburón Amarillo, Tiburón Arenero, Tiburón Gambuso, Tiburón Lamia, Tiburón Lobo, Tiburón Marrón, Tiburón Obscuro, Tiburón Oscuro, Tiburn Amarillo, Tiburon Arenero, Tiburn Gambuso, Tiburn Lamia, Tiburn Lobo, Tiburn Marrn, Tiburn Obscuro, Tiburn Oscuro, Tintorera, Zarco

Common Names in Swedish:

Mörkhaj, Mrkhaj

Common Names in Turkish:

Köpek Baligi, Köpek Balığı, Kpek Baligi

Common Names in Vietnamese:

C M?p S?m

Description

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Family Carcharhinidae

Distribution: global. Gill openings 5, the fifth behind origin of pectoral fin. Small to large sharks with round eyes, internal nictitating eyelids , no nasoral grooves or barbels , usually no spiracles. Teeth usually bladelike with one cusp . Development usually viviparous with young born fully developed. Includes several dangerous species, but most prefer to avoid divers .The family Carcharhinidae belongs to the Class Elasmobranchii (sharks and rays ) and the Order Carcharhiniformes. It contains 12 genera and 50 species. It may be found in Marine , Brackish , and Freshwater environments and is primarily Marine. Members of this family are not used in the aquarium trade. Reproductively, most members of this family are bearers. The main mode of swimming of adult fish in this family is carangiform . Compared with other fish, the activity level of this family tends to be active . Members of this family have been dated back to the lower Eocene epoch of the Tertiary period. This family may be found from 41° n to 35° s and 115° w to 168° e. Etymology of this family name : Greek, karcharos, -ou = cutting, sharp and also a kind of shark + Greek, rhinos = nose

Physical Description

Species Carcharhinus obscurus

Distinctive Features: This species is characterized by a snout that is slightly shorter than or as long as the width of the mouth , origin of the first dorsal fin over the free rear tip of moderately large falcate pectoral fins, and a low interdorsal ridge . The dusky shark is sometimes confused with the sandbar shark (Carcharhinus plumbeus ) but can easily be distinguished by its smaller and more posterior first dorsal fin.

Dentition: Upper teeth are triangular and slightly oblique with serrated edges . Lower teeth are erect , narrowly cusped and more finely serrated. Both sets of teeth become increasingly concave as they move distally in the jaw.

Dermal Denticles : The dermal denticles for C. obscurus are large, closely imbricated , and show five keels with five distinct pointed lobes . The denticles rest on a large rhomboidal base plate .

Color:

Typical of many of the carcharhinids, the dusky shark is bluish gray above and white below. Tips of most fins dusky in younger sharks but inconspicuous in adults .

Size/Age/Growth

A large shark , C. obscurus can attain a length of about 400 cm (12.5 ft ). Average size and weight are 320 cm (10 ft) and 160-180 kg (350-395 lbs ), respectively. Males mature at about 280 cm (8.5 ft) and females the same or slightly larger. Size at birth ranges from 70-100 cm (33-39 in). Dusky sharks are very slow growing, mature at about 20 years and may live as long as 45 years.Males are commonly 250 cm (Total Length) in length when caught/marketed, but may be as large as 420 cm (Total Length).

Habitat

C. obscurus occurs along continental shorelines where it ranges from shallow inshore waters to the outer reaches of the continental shelf and adjacent oceanic waters. Although generally a bottom feeder , it can be found from the surface to a depth of 400 m (1240 ft ). Adults of this species tend to avoid areas of low salinity and rarely enter estuaries. The young congregate in very shallow coastal water (nurseries) in estuaries and bays from New Jersey to Cape Hattaras.

This species is known to be highly migratory in the western Atlantic and eastern Pacific, moving north during the summer months and south in the winter. Males and females undertake these seasonal migrations separately.

Along the coast of South Africa, immature dusky sharks are known to undergo sex-segregated migrations with females moving north and males moving south. However, this phenomenon is complicated by the occurrence of temperature-regulated seasonal migration with sharks traveling southward during summer and northward in winter. This, in turn , is further complicated by the tendency for some sharks to move into deeper water during summer months.

In comparison, dusky sharks in western Australia undergo distinct seasonal migrations with both adolescents and adults moving inshore during summer and autumn.

May be found at depths of 0 to 400 meters. Usually found at depths of 200 to 400 meters.

Typically found at an altitude of 0 to 482 meters (0 to 1,581 feet).[7]

Biome: Brackish water, saltwater . Reef-associated .

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.[8]


List of Habitats :9.1Marine Neritic - Pelagic 10.1Marine Oceanic - Epipelagic (0-200m)

Biology

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Diet

Preys on a wide array of bony and cartilaginous fishes as well as a variety of invertebrates . Food items include herring , eels, mullet, groupers, grunts , croakers, bluefish, mackerel , tunas , various flatfish , a variety of sharks , skates and rays , crabs, octopuses, squid, starfish and sometimes human refuse.

Reproduction

In the western Atlantic, mating occurs in the spring . Due to the presence of two class sizes of young found in pregnant females off the coast of Florida, it is believed that females of this species only mate every second year. These different class sizes suggest alternating birth seasons every two years with a gestation period of about 8 months or a single season with a longer gestation period of about 16 months.

As with other carcharhinids, developing embryos are nourished via a pseudo-placental sac , a reproductive strategy known as viviparity . In the western Atlantic, the number of young per liter ranges from 6-10 with an average of 8, whereas in the southeastern Atlantic, numbers are slightly higher (range 6-14, average 10). In both cases, both sexes are represented in a 1:1 ratio.

Populations off the coast of Africa show no distinct breeding season although it appears that the young are born throughout the year with an increase in births from April to June. In the western North Atlantic, females give birth in the shallow bays and estuaries along the southeastern United States leave the area shortly after. This shallow water habitat provides a 'nursery' area for young sharks where they are afforded protection from larger sharks.

Migration

Oceanodromous .

Behavior

Predators:

Young dusky sharks may fall prey to larger sharks including the bull shark . However, mature dusky sharks have few if any predators .

Parasites:

Pandarus sinuatus, a copepod, is parasitic on the body surface of the dusky shark .

Taxonomy

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Ambiguous Synonyms

  1. Carcharhinus lamiella (Non Jordan and Gilbert, 1882)
  2. Galeolamna greyi Owen, 1853

Unambiguous Synonyms

  1. Carcharhinus iranzae Fourmanoir, 1961
  2. Carcharhinus obscurella Deng, Xiong & Zhan, 1981
  3. Carcharias macrurus Ramsay & Ogilby, 1887
  4. Carcharinus iranzae Fourmanoir, 1961
  5. Carcharinus obscurus (Lesueur, 1818)
  6. Eulamia obscura (Lesueur, 1818)
  7. Galeolamna eblis Whitley, 1944
  8. Galeolamna macrurus (Ramsay & Ogilby, 1887)
  9. Prionodon obvelatus Valenciennes, 1844
  10. Squalus obscurus Lesueur, 1818

Misapplied Names

  1. Carcharhinus lamiella (non Jordan & Gilbert, 1882)

Notes

Name Status: Accepted Name .

Family : Requiem sharks .

Similar Species

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Members of the genus Carcharhinus

There are approximately 72 species in this genus:

C. acronotus (Blacknose Shark) · C. ahenea · C. albimarginatus (Silver-Tip Shark) · C. altima · C. altimus (Knopp´s Shark) · C. amblyrhynchoides (Queensland Shark) · C. amblyrhynchos (Shortnose Blacktail Shark) · C. amblyrhynchus · C. amboinensis (Ambon Sharpnose Puffer) · C. azureus · C. borneensis (Borneo Mullet) · C. brachyurus (Bronze Shark Whaler) · C. brevipinna (Great Blacktip Shark) · C. cautus (Nervous Shark) · C. cerdale · C. commersoni · C. commersonii · C. dussumieri (White-Cheeked Whaler Shark) · C. egertoni · C. elongatus · C. falciformis (Sickle-Shaped Shark) · C. fitzroyensis (Creek Whaler) · C. floridanus · C. frequens · C. galapagensis (Grey Reef Whaler) · C. glauca · C. glaucus · C. hemiodon (Pondicherry Shark) · C. isodon (Smoothtooth Shark) · C. japonicus · C. lamia · C. obscurus · C. leiodon (Smooth Tooth Blacktip Shark) · C. leucas (Freshwater Whaler) · C. limbatus (Small Black Tipped Shark) · C. littoralis · C. longimanus (Brown Milbert's Sand Bar Shark) · C. macloti (Hardnose Shark) · C. macrurus · C. maculipinnis · C. longimanus · C. melanoptera · C. melanopterus (Black Fin Reef Shark) · C. sealei · C. milberti · C. natator · C. nicaraguensis · C. obscurus (Brown Common Gray Shark) · C. obtusus · C. oxyrhynchus · C. perezi (Caribbean Reef Shark) · C. perezii (Caribbean Reef Shark) · C. plumbeus · C. platyrhynchus · C. plumbeus (Thickskin Shark) · C. porosus (Tiburon Peninsula Limia) · C. priscus · C. remotus · C. sealei (Black-Spot Shark) · C. signatus (Night Shark) · C. sorrah (Spot-Tail Whaler) · C. amblyrhynchos · C. springeri · C. taurus · C. tephrodes · C. tilstoni (Whitley´s Blacktip Shark) · C. tjutjot · C. velox · C. wheeleri · C. zambezensis · C. sealei · C. limbatus

More Info

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Further Reading

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Notes

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Contributors

Data Sources

Accessed through GBIF Data Portal March 01, 2008:

Identifiers

Footnotes

  1. Compagno, L.J.V., D.A. Ebert and M.J. Smale (1989). Guide to the sharks and rays of southern Africa. New Holland (Publ.) Ltd., London. 158 p. [back]
  2. Bass, A.J., P.C. Heemstra and L.J.V Compagno (1986). Carcharhinidae. p. 67-87. In M.M. Smith and P.C. Heemstra (eds.) Smiths' sea fishes. Springer-Verlag, Berlin. [back]
  3. Last, P.R. and J.D. Stevens (1994). Sharks and rays of Australia. CSIRO, Australia. 513 p. [back]
  4. Dulvy, N.K. and J.D. Reynolds (1997). Evolutionary transitions among egg-laying, live-bearing and maternal inputs in sharks and rays. Proc. R. Soc. Lond. B 264:1309-1315. [back]
  5. Halstead, B.W. (1980). Dangerous marine animals. Cornell Maritime Press, Inc., Maryland, U.S.A. [back]
  6. 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. Part 2. Carcharhiniformes. FAO Fish. Synop. (125, Vol. 4, Part 2), 655 p. [back]
  7. Mean = -636.150 meters (-2,087.106 feet), Standard Deviation = 1,444.310 based on 642 observations. Altitude information for each observation from British Oceanographic Data Centre. [back]
  8. Shark Specialist Group 2000. In IUCN 2008. 2008 IUCN Red List of Threatened Species. IUCNRedList.org. Downloaded July 19, 2008. [back]
Last Revised: 2009-05-11