The data from this study indicate that Pacific sleeper sharks need to be considered as a possible source of mortality of juvenile Steller sea lions in the region of the Gulf of Alaska.
Here, we provide indirect evidence (from LHX tag data) of predation by Pacific sleeper sharks on juvenile Steller sea lions.
The postmortem ingestion by Pacific sleeper sharks of tags released through the attack of a different predator is another possible interpretation.
encounter of a sea lion and 2 distinct predator species at depth would be very low, in part because it would expose Pacific sleeper sharks to predation risk (Ford et al.
Pacific sleeper sharks have been documented in shallow coastal waters and even in estuarine waters in the arctic regions of the North Pacific and at oceanic depths (>2700 m) in temperate latitudes (Compagno, 1984; Ebert et al.
Pacific sleeper sharks have a broad range of diet that includes benthic and mid-water crustaceans, cephalopods, salmonids, gadids, flatfish, and marine mammals (Bright, 1959; Compagno, 1984; Yang and Page, 1998; Orlov, 1999; Orlov and Moiseev, 1998, 1999; Sigler et al.
Pacific sleeper sharks may appear to be improbable predators of fast-swimming and agile prey as large as juvenile Steller sea lions, especially given the adaptation of the functional morphology of their feeding apparatus toward suction feeding.
Pacific sleeper sharks do appear capable of preying on fast-swimming salmonids and scombrids (Ebert et al.
Yet, no sea lion remains were identified in the stomachs of 198 Pacific sleeper sharks caught by long-lining near sea lion rookeries (Sigler et al.
Courtney and Foy (2012) reported an increase in trophic position with TL in Pacific sleeper sharks.
In Prince William Sound, Alaska, Pacific sleeper sharks
keep harbor seals from eating too many walleye pollock, wrote Dalhousie marine biology professor Boris Worm, the lead author of a recent paper in Trends in Ecology and Evolution, in an e-mail.