The ecological importance of sharks in polar and subpolar waters is poorly understood. Pacific sleeper sharks (Somniosus pacificus) are large, cold-water predators and scavengers incidentally caught by commercial fishing operations (this is known as ‘bycatch’). Knowing how many sharks there are and where they occur, how much energy they need to carry out a normal life, and what it might mean if they are removed from the food web –through bycatch or predation—will help us work towards sustaining a healthy ocean.
Evidence from their close relatives – the Greenland shark (Somniosus microcephalus) – suggests sharks in the genus Somniosus are very slow-growing and long-lived. In fact, they may be one of the longest-lived vertebrates on our planet, possibly living to several hundred years in age (though this has not been confirmed for the Pacific sleeper shark). Given this expected extreme longevity and possibly broad distribution in cold waters, it is quite likely that Pacific sleeper sharks play a key role in arctic marine ecosystems that have been completely ignored.
In 2018, our team jumpstarted a coordinated series of innovative studies to explore the behavior and physiology of this enigmatic species. Through 2021, we caught, sampled, tagged, and released 45 immature Pacific sleeper sharks in Resurrection Bay near Seward, Alaska. We brought two of these back to the Alaska SeaLife Center for a brief period of intense studies before releasing them back into the wild. We satellite-tagged ten of these sharks to begin looking at their movement patterns.
Now, in this continuing project, we will be catching, sampling and satellite-tagging additional sharks in Prince William Sound, to further study movement and space use patterns, characterize their habitat and trophic positioning (how high up in the food chain do they eat?). From this effort, we hope to obtain more information about their site residency and return to locations of interest, such as salmon runs. We are also hoping to learn more about predators of these sharks. Yes, there are animals that eat these sharks – more on that in other sections of this project!