Interactions between Humans and Sea Otters in Holocene British Columbia: Evidence from Stable Isotope Analysis

We examined the isotopic composition (δ¹³C and δ¹⁵N) of sea otter (Enhydra lutris) bone collagen from late Holocene (ca. 5200 years BP – AD 1900) archaeological sites in northern British Columbia, Canada. These data suggest that sea otter diets were composed primarily of benthic invertebrates, with a very low reliance on epibenthic fish. Given the large number of potential prey for sea otters based on studies of extant populations, there is very little isotopic and thus dietary variability in BC sea otters during the late Holocene, suggesting a lack of individual dietary specialization. This lack of piscivory and dietary specialization, combined with the abundance of sea otters in faunal assemblages, is suggestive of top-down control on sea otter populations through consistent, but sustainable, hunting by aboriginal peoples.