Sleeper Shark (Somniosus pacificus) in Kasitsna Bay

Observation by Michael Opheim

Last weekend a family out digging for clams in Kasitsna Bay happened upon a dead Sleeper Shark at the high tide line. It looks like the jaws and fins were harvested from it. We have never seen or heard of Sleeper Sharks in Kachemak Bay before. Maybe it was caught by a longliner and put back overboard but didn't survive or maybe it died of natural causes and washed up on the beach and was then harvested from. We checked around to see if anyone wanted any samples from it since we had access to it but no one was currently doing any work with this species of shark. It would be interesting to know if there have been other sightings or if this is part of their range. This shark was probably 9 to 10 feet in length.

Gay Sheffield, Alaska SeaGrant Bering Strait Marine Advisory Agent, writes:

The shark looks too decomposed to say whether the fins were harvested, rotted off, or were eaten by scavengers. The Sleeper shark is within its range and not an uncommon shark in the Gulf of Alaska.

Shark Researcher **Bruce Wright writes: "A 10-foot sleeper shark is probably 400+ years old."

Comments by LEO Editors

The Alaska Sea Life Center in Seward, AK has partnered with the Shark Research Laboratory at California State University, Long Beach to study the sleeper shark in Pacific waters. The sleeper shark (Somniosus pacificus) is a species that is understudied, yet has an important ecological role in marine ecosystems. It is slow-moving and slow to reproduce; the females do not reproduce until they are about 4 meters in length and well over 120 years old. They enjoy cold waters and extreme depths (often deeper than 2,000 meters) in the North arctic and the Continental Slope. Sleeper sharks also roam in shallower waters as their range approach the more northerly latitudes. These sharks have a broad diet which includes fish, squid, seafloor-dwelling invertebrates, and marine mammals. According to the Pacific Sleeper Shark Research Project Pacific sleeper sharks in Alaskan waters move up and down the water column, sinking during the day and floating to within 150 feet of the surface at night, likely hunting prey.

Sleeper sharks do not have much commercial economic value but are frequently caught as by-catch in longline and trawl fisheries here in Alaska. The Pacific Sleeper Shark Research Project reports that "captured sharks often become entangled in lines and gear, meaning that injuries and death related to capture (also known as “discard mortality”) may be high for this species." Because they are slow to reproduce, there are concerns about the conservation of the species. Reports of Pacific Sleeper Sharks are rare. This is the third sighting reported in LEO Network. The first was in June of 2021 in King Cove Alaska reported by AnnDee Roehl. The second was in Shishmaref in October of 2014, reported by Gay Sheffield; a shark which was mistaken as a seal and harvested. That shark was sent to the Museum of the North at the University of Alaska Fairbanks. Chyna Williams and Mike Brubaker