Ecological Impact of Spawning Pacific Salmon (Oncorhynchus spp.) on Three Major Predators in Southeast Alaska

Pacific salmon (Oncorhynchus spp.) provide substantial marine derived nutrients and biomass to freshwater ecosystems along the Pacific coast. In Alaska three major consumers of salmon and their eggs are brown bears (Ursus arctos), glaucous-winged gulls (Larus glaucescens), and coastrange sculpin (Cottus aleuticus). Our study examines the behavioral and physiological impact that Pacific salmon have on these predators in Berners Bay, Alaska. We will examine spatial and temporal use of Berners Bay by brown bears and glaucous-winged gulls during the salmon spawning migration. Quantifying the distribution of bears and gulls relative to spatially and temporally varying salmon runs will help us infer how these predators track this resource. We will also test whether coastrange sculpin exhibit compensatory growth when fed a temporally limited diet of salmon eggs, while held at a range of temperatures. In a warm summer (2013) sculpin did not exhibit compensatory growth, but in a cool year (2014) they did. In 2015, field and laboratory experiments will explore the role of temperature and salmon egg availability on sculpin growth. This research will help us understand changes in the physiology and phenology of salmon consumers as salmon populations shift their migration timing in response to changing physical conditions.