Pacific Sleeper Shark

About the Pacific Sleeper Shark

The Somniosus Pacificus shark, also known as the Pacific Sleeper Shark, is a deepwater shark, relatively common in the north Pacific Ocean.


The species attains a maximum length of at least 440cm with unconfirmed records of up to 700 cm total length. Adult females measure from 370 to 430 cm TL. Males are mature by at least 397 cm TL. Larger individuals of up to 700 cm have been photographed in deep waters.


The Pacific Sleeper Shark is an ovoviviparous species, with 300 pups in a litter. Development is yolk-sac viviparity, but pregnant females are rare and yet to be found. This is possible because of the segregation of pregnant females beyond the usual fisheries gear that captures these sharks or extremely low fecundity. Size at birth is between 40 and 65 cm TL suggesting that fecundity may indeed be high for this species given the enormous size of the females.  


This species is found on continental shelves and slopes. 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.


The Pacific Sleeper shark feeds on a wide variety of surface and bottom animals such as fishes, octopi, squids, crabs, tritons, and carrion. The smallmouths and long heads and oral cavities of these sharks suggest that they are powerful suction feeders, but this has yet to be observed.


This species is taken as bycatch in several fisheries and usually discarded.

There is no current conservation measure for this species. Like many other deeper water species more information on biology, ecology and importance in fisheries are required to further asses status and any future conservation needs. The total population of this species is known.

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Pacific Sleeper Shark Gallery

Scientific Name Somniosus pacificus
OrderDog and Angelfish Sharks - Squaliformes
CitesNot Listed
IUCNData Deficient
Litter Size 10
Common Length 440 cm
Max LenghtNA
Depth Range 0 - 2000 m
DistributionNortheast Pacific, Northwest Pacific