Feeding success of harbor seals in relation to hunting technique at Whatcom Creek

Factors that influence hunting success of seals and sea lions are underrepresented in studies of animal behavior. This is a critical interaction to understand when evaluating the top-down effects of pinnipeds on endangered Pacific salmon (Oncorhynchus spp.). In the Pacific Northwest, harbor seals (Phoca vitulina) consume a very large number of individual salmon, species that are a valuable resource and the subject of costly restorative efforts. A salmon hatchery in Whatcom Creek estuary of downtown Bellingham, Washington, attracts harbor seals that prey on returning adult Pacific salmon. The convenient location and small size of the site allows consistent observation of hunting behavior. I will describe the success of individual seals relative to the hunting technique that they employ by recording behavioral events and states and taking photos of seals for identification of individuals. When hunting behavior is observed, the specific hunting technique employed will be noted as resulting in a successful or unsuccessful catch and subsequently tied to an individual seal. I will then evaluate which hunting techniques allow a seal to catch prey with higher success, which individuals are more skillful in capturing prey, and whether they prefer specific hunting technique. This study will provide estimates of salmon consumption by harbor seals in Whatcom Creek. Further, by describing the foraging success of individual harbor seals relative to hunting technique, it will enhance our understanding of pinniped foraging behavior.