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Carcharhinus obscurus  (Lesueur, 1818)

Dusky shark
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Native range | All suitable habitat | Point map | Year 2100
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Carcharhinus obscurus   AquaMaps   Data sources: GBIF OBIS
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Image of Carcharhinus obscurus (Dusky shark)
Carcharhinus obscurus
Picture by Randall, J.E.


Australia country information

Common names: Black whaler, Black whaler shark, Bronze shark whaler
Occurrence: native
Salinity: marine
Abundance: common (usually seen) | Ref:
Importance: commercial | Ref: Last, P.R. and J.D. Stevens, 1994
Aquaculture: | Ref:
Regulations: restricted | Ref: Kailola, P.J., M.J. Williams, P.C. Stewart, R.E. Reichelt, A. McNee and C. Grieve, 1993
Uses: gamefish: yes;
Comments: Occurs throughout Australia but rare off southern Tasmania (Ref. 6871). Also found in the Arafura Sea (Ref. 9819). Enters large coastal bays and inshore areas occasionally. Dusky whalers avoid estuaries and areas of low salinities (Ref. 244). Migratory behavior suggests a single stock in the area. Records of long migrations in Western Australia start from the region between Augusta and Shark Bay, then to as far away as Rowley shoals off the northwest coast and Esperance on the southeast coast (Ref. 13842). Dusky whalers migrate following the warmer water southwards in the spring and summer, and northwards in the autumn and winter. Seasonal, inshore-offshore movements also occur when pregnant females move from outer continental shelf regions onto the inner shelf to pup, and move back after giving birth. Commercial fishery: In Western Australia, major catch areas are from between the Albany and Busselton regions of the Southwest Shark Fishery. Dusky whalers are caught mainly with bottom set gillnets, bottom set longlines, droplines, and handlines. Newly born and small juveniles of around 100 cm TL are primarily exploited (Refs. 6871, 13842). In the South Australian inshore fishery, dusky whalers are caught in west coast bays, Spencer Gulf and Gulf St. Vincent, off the Murray River mouth and the southeast coast. Juveniles of less than 150 cm TL are caught with large mesh bottom set gillnets and bottom set longlines. They are sold fresh and frozen and is very popular in the fish-and-chip trade. Recreational fishery: Jetties such as at Giles Point and Rapid Bay in South Australia, and Lorne and Point Lonsdale in Victoria are frequented by gamefishers for catching dusky whalers. They use moderately heavy lines with wire or light chain traces, and gamefishing tackle. About 5% of all sharks caught by the New South Wales gamefishing clubs between Port Macquarie and Sydney are dusky whalers. Sharks belonging to family Carcharhinidae only comprise 24% of the total shark catch (Ref. 26106). Resource status: Juveniles are mostly targeted in this fishery. However, the extent of the nursery areas is not known so the level of exploitation cannot be determined. There is not much information on the status of the adults as well. Current levels of fishing maybe sustainable probably because the stocks are not being fished over the extent of their range due to their migratory habits (Ref. 13842). Also Ref. 244, 2334, 7300, 9997.
National Checklist:
Country Information: httpss://www.cia.gov/library/publications/resources/the-world-factbook/geos/as.html
National Fisheries Authority: https://www.csiro.au/
Occurrences: Occurrences Point map
Main Ref: Kailola, P.J., M.J. Williams, P.C. Stewart, R.E. Reichelt, A. McNee and C. Grieve, 1993
National Database:

Classification / Names

Elasmobranchii (sharks and rays) > Carcharhiniformes (Ground sharks) > Carcharhinidae (Requiem sharks)
Common names | Synonyms | Catalog of Fishes (gen., sp.) | ITIS | CoL

Common names from other countries

Main reference

Size / Weight / Age

Max length : 420 cm TL male/unsexed; (Ref. 5578); common length : 250 cm TL male/unsexed; (Ref. 26999); max. published weight: 346.5 kg (Ref. 4699); max. reported age: 40 years (Ref. 31395)

Length at first maturity
Lm 235.0, range 220 - 300 cm

Environment

Marine; brackish; reef-associated; oceanodromous (Ref. 51243); depth range 0 - 400 m (Ref. 244), usually 200 - 400 m

Climate / Range

Subtropical; 45°N - 46°S, 120°W - 156°E (Ref. 55186)

Distribution

Western Atlantic: southern Massachusetts to Florida (USA), Georges Bank, Bahamas, Cuba, northern Gulf of Mexico, Nicaragua, southern Brazil and Uruguay (Ref. 58839). Eastern Atlantic: Canary Islands, Cape Verde, Senegal, Sierra Leone. Some records from the Mediterranean and Madeira may be based on Carcharhinus galapagensis. Indo-West Pacific: Red Sea (Ref. 5485), Mozambique and South Africa to Japan, China, Viet Nam and Australia. Eastern Pacific: southern California, USA to Gulf of California and the Revillagigedo Island. Highly migratory species, Annex I of the 1982 Convention on the Law of the Sea (Ref. 26139).
Countries | FAO areas | Ecosystems | Occurrences | Introductions

Short description

Dorsal spines (total): 0; Dorsal soft rays (total): 0; Anal spines: 0; Anal soft rays: 0. A large shark with a broadly rounded snout, triangular saw-edged upper teeth, curved moderate-sized pectoral fins, and an interdorsal ridge (Ref. 5578). Blue-grey, lead-grey above, white below; tips of pectoral and pelvic fins, as well as lower lobe of caudal fin and dorsal fins often dusky in young, plain in adults (Ref. 9997).

Biology     Glossary (e.g. epibenthic)

Found in coastal and offshore waters but not oceanic (Ref. 5578). Adults are commonly found at depths of 200-400 m, young in shallower waters (Ref. 5485). A seasonal migratory species over parts of its range (Ref. 6871). Common component of the catch of the shark longline fishery (Ref.58048). Feeds on bottom and pelagic bony fish, sharks, skates, rays, cephalopods, gastropods, crustaceans, sometimes mammalian carrion and inorganic objects (Ref. 5578). Viviparous (Ref. 50449); with litter size number from 3-14 (Ref. 27549). Large adults are potentially dangerous (Ref. 4716, 6871). Utilized fresh, dried-salted, frozen and smoked for human consumption; hides for leather; fins for sharks-fin soup; and liver oil extracted for vitamins (Ref. 244).

IUCN Red List Status (Ref. 115185)

  Vulnerable (VU) (A2bd)

Threat to humans

  Traumatogenic (Ref. 4690)



Human uses

Fisheries: commercial; gamefish: yes

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Estimates of some properties based on models

Phylogenetic diversity index (Ref. 82805)
PD50 = 0.5000 many relatives (e.g. carps) 0.5 - 2.0 few relatives (e.g. lungfishes)

Trophic Level (Ref. 69278)
4.3   ±0.2 se; Based on diet studies.

Resilience (Ref. 69278)
Very Low, minimum population doubling time more than 14 years (rm=0.02; also Musick et al. 2000 (Ref. 36717))

Vulnerability (Ref. 59153)
Very high vulnerability (88 of 100)
Price category (Ref. 80766)
Medium