Behavioral observations and stable isotopes reveal high individual variation and little seasonal variation in sea otter diets in Southeast Alaska

Two complementary approaches were used to assess year-round variation in the diet of sea otters Enhydra lutris around Prince Wales Island (POW) southern Southeast Alaska, a region characterized by mixed-bottom habitat. We observed foraging determine composition during spring and summer. Then, we obtained otter vibrissae, which record temporal patterns as they grow, from subsistence hunters identify changes diets via stable isotope analysis carbon (δ 13 C) nitrogen 15 N). compared isotopes vibrissae prey items that collected spring, summer, winter. Overall, estimates signatures visual observations summer dominated clams terms biomass, with butter Saxidomus gigantea most common clam species seen observations. Our results indicate these otters, when considered together at regional level POW, do not exhibit shifts main source season or location. However, identified had strong individual-level variation. Behavioral among individual may be primary driving factor composition. This study provides quantitative data for modeling predictions invertebrate population aid future management shellfisheries hunting development co-management strategies this protected species.