E-Fauna BC: Electronic Atlas of the Wildlife of British Columbia

Somniosus pacificus Bigelow & Schroeder, 1944
Greenland Shark; Pacific Sleeper Shark
Family: Dalatiidae

© Public Domain  Email the photographer   (Photo ID #14505)

Source: Distribution of Somniosus pacificus as compiled by Aquamaps
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The Pacific Sleeper Shark (which is essentially a giant dogfish) is a common large temperate species found in the "Northwest Pacific to northeast Pacific: Japan along the Kuril Islands, Sea of Okhotsk and Bering Sea (Russia) to the Chukchi Sea and southward to southern California (USA), and Baja California (Mexico) (Ebert, 2003). Also, recently found off Taiwan (Wang and Yang 2004)" (IUCN 2011). It occurs at depths ranging from 0 to 2000 m (Fishbase 2011, IUCN 2011). It may be found in shallower waters at the northern extent of its range, but is found only in deep waters are the lower extent of its range (IUCN 2011). Lengths are confirmed up to 4.4 m (14 ft.), however, lengths of up to 7 m (25 ft.) are reported-- a Pacific Sleeper Shark filmed in Japan was estimated to be 7 m (23 ft.) in length (Fishbase 2011, IUCN 2011). Diet is varied and includes cephalopods, flatfish and Harbour Seals (Taggart et al. 2005)--research shows that this is one of two species reported to feed on mature giant squid and colossal squid; the other is the Sperm Whale (Wikipedia 2011). Recent observation by researchers has shown that Killer Whales prey on Pacific Sleeper Sharks--read more about this.

This species is presently common in the North Pacific, however, it is significantly affected by fisheries operations. The IUCN (2001) says: "This species is taken as bycatch in several fisheries and usually discarded. It is notably affected by bottom trawl fisheries in the western Bering Sea (Orlov 2005), by longline fisheries for sablefish and Pacific halibut in the eastern North Pacific (Courtney et al. 2006a, b). Incidental catch in US waters in 2006 was 435 mt, in some years it has reached ~ 1,400 mt (Courtney et al. 2006a, b)". Detailed information on it population numbers, ecology and biology is lacking (IUCN 2011):

Species Information

Dorsal spines (total): 0; Anal spines: 0. Uniformly greyish-pink with bluish black fins; live specimens probably with white spots on dorsal surface (Ref. 6871). Short rounded snout, heavily cylindrical body and small precaudal fins, equal-sized dorsal fins, asymmetrical caudal fin with a well-developed ventral lobe (Ref. 6871), first dorsal fin on back closer to pelvic fins than pectoral fins, interdorsal space less than distance from snout tip to first gill openings, no short keels on base of caudal fin, upper teeth lanceolate, lower teeth with short, low, strongly oblique cusps and high narrow roots (Ref. 247).

Source: FishBase. Compagno, L.J.V. 1984 . (Ref. 247)


Species Biology

Found on continental shelves and slopes (Ref. 247). At high latitudes, it occurs in littoral and even intertidal areas; in lower latitudes it may never come to the surface and ranges down to at least 2,000 m (Ref. 247). Feeds on bottom animals such as fishes, octopi, squids, crabs and tritons; also harbor seals and carrion (Ref. 247). Ovoviviparous (Ref. 205), with 300 pups in a litter (Ref. 247), length at birth about 42 cm or less (Ref. 26346). Environment: benthopelagic; marine; depth range 0 - 2000 m (Ref. 26346). Climate: temperate; 70°N - 47°S

Source: FishBase. Compagno, L.J.V. 1984 . (Ref. 247)



North Pacific: Japan and along the Siberian coast to the Bering Sea, southern California (USA), and Baja California, Mexico. Sporadic records from the South Pacific (assignment of large southern hemisphere Somniosus to the North Pacific Somniosus pacificus is tentative) (Ref. 31367). In Australasian waters, it occurs from the seamounts south of Tasmania, the Challenger Plateau (off eastern New Zealand) and possibly from Macquarie Island (Ref. 6871). Southwest Atlantic: off Uruguay (Ref. 35864), Brazil (Ref. 53443) and Argentina (Ref. 58839).

Source: FishBase. Compagno, L.J.V. 1984 . (Ref. 247)

Status Information

Origin StatusProvincial StatusBC List
(Red Blue List)
NativeSNRNo StatusNot Listed
BC Ministry of Environment: BC Species and Ecosystems Explorer--the authoritative source for conservation information in British Columbia.

Additional Notes

The liver of the Pacific Sleeper Shark is physiologically different as an adaptation to living in deep cold water: "Due to living in frigid depths the sleeper shark's liver oil contains no squalene because it would solidify into a dense, non-buoyant mass. Rather than squalene, the low-density compounds in the sharks' liver are diacylglyceryl ethers (DAGE) and triacylglycerol (TAG) which maintain their fluidity even at the lowest temperatures" (Wikipedia 2011).

Additional Range and Status Information Links

Additional Photo Sources

General References

Recommended citation: Author, Date. Page title. In Klinkenberg, Brian. (Editor) 2019. E-Fauna BC: Electronic Atlas of the Fauna of British Columbia [efauna.bc.ca]. Lab for Advanced Spatial Analysis, Department of Geography, University of British Columbia, Vancouver. [Accessed: 2020-07-08 10:40:29 PM]
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