Foraging Ecology of Harbor Seals (Phoca vitulina) in Hood Canal and the Potential Impacts on Threatened Salmonid Stocks Based on Scat Genetics and Direct Observation.

In the fall of 1998-2000, the Washington Department of Fish and Wildlife (WDFW) and Washington Cooperative Fish and Wildlife Research Unit began efforts to evaluate the potentially negative effects of predation by pinnipeds on the recovery of summer chum salmon runs in Hood Canal. Hood Canal has been the focus of these efforts because of the isolated nature of the system and the presence of abundant harbor seal (Phoca vitulina) populations along declining summer chum stocks. Surface observations were used to document harbor seal predation on returning adult salmon off the mouths of the Quilcene, Dosewallips, Duckabush, and Hamma Hamma river systems. Seals were observed consuming summer chum, coho, and fall chum in all three years. Additionally, steelhead, pink and chinook salmon were observed in 1999. During 1998 and 1999, 1017 (98: 601; 99:416) scat samples were collected at five haul-outs to determine food habits and provide additional insights into salmonid consumption. Key questions regarding nighttime predation rates and allocation of unidentified salmonid predations to a particular species remain unanswered and are currently being addressed. Preliminary results suggest that salmon are a significant component of harbor seal diets. However, it is not yet known whether the levels of predation observed have the potential to negatively impact recovery of summer chum runs.