LB 36-295 - Movement ecology and the unique mucus layer of the pacific sleeper shark.

Pacific Sleeper sharks (Somniosis pacificus) are an understudied species, although they are often bycaught by commercial fisheries. Much of their ecology and behavior, such as population size and dynamics, movement ecology, and their potential impact on the ecosystem remain unknown. Over the summer of 2022, we captured, measured, and tagged 16 sleeper sharks over 29 days in multiple locations within Prince William Sound (PWS), Alaska. When supplemented with previous years’ data from an additional 12 sharks, we can start to identify patterns in individual characteristics, movements, and habitat use. To date, there has never been a recapture of any individual – which may indicate a large population size. For this study, we noted that body morphologies of all the captured individuals seemed to be diverse. Specifically, sharks caught in PWS had a higher incidence of scarring and previous injuries relative to other regions. These could be related to higher interactions with fishing gear in the area. The mucus layer of sharks and rays is understudied; however, we have observed sleeper sharks with deteriorated mucus layers, revealing the white epidermis underneath. Other shark species’ mucus layers offer benefits such as drag reduction and pathogen protection. If this functions similarly in Pacific sleeper sharks, the mucus layer may directly influence body condition and subsequently fitness, especially if they engage in predatory behavior. Here we present a preliminary look at the coverage of the mucus layer of 23 individuals captured in Resurrection Bay (RB), and PWS between 2018 and 2022. Total percent mucus cover (MC) was quantified using ImageJ, and Fulton’s K was used to find body condition (BC) from total length (TL) and body mass (BM). On average, sharks had 83.9% of mucus cover and a body condition of 93.4%. Females (Nf16) had significantly lower MC (79.7%) than males (93.5%, P < 0.05); but differences in BC was not significant between sexes (females BC = 93.2%, male BC = 93.5%). Individuals captured in RB had 84.8% MC and 93.1% BC, while those captured in PWS had 83.1% MC and 93.1% BC. Differences of average MC and BC between RB and PWS locations were not significant. While this study is preliminary with a small sample size, these trends in mucus cover and body condition validate the need for conducting more research to better understand the ecological role of this species.