Pinniped strandings can be used as a proxy to evaluate the impacts of anthropogenic activities on the local marine environment. Stranding data from Oregon and Washington from 1991 to 2016 were used to examine regional and temporal patterns in strandings and human interaction cases across age and sex for six species. Over the study period, 14,729 pinnipeds were reported stranded along the coast in the Pacific Northwest, 11% of which were documented as human interaction cases. Total strandings and the number of reported human interaction cases increased over time for most species. The composition of age and sex classes varied for each species, as did the proportion of strandings identified as human interaction cases. Gunshot wounds and fisheries entanglements were concentrated in clusters along the coast and together constituted the majority of human interaction cases. Stranding and human interaction case hotspots were different across species and varied seasonally, likely due to the distribution of pinnipeds and human activities along the coast. Despite the challenges and uncertainties inherent in using stranding data as an indicator of pinniped health and anthropogenic impacts, modeling spatio-temporal patterns is useful for stranding response practitioners and natural resource managers when evaluating the scope and magnitude of threats to pinniped populations.
Citation:
Warlick, A.J., D.A. Duffield, D.M. Lambourn, S.J. Jeffries, J.M. Rice, J.K. Gaydos, J.L. Huggins, J. Calambokidis, L.L. Lahner, J. Olson, E. D’Agnese, V. Souze, A. Elsby, and S.A. Norman. 2018. Spatio-Temporal Characterization of Pinniped Strandings and Human Interaction Cases in the Pacific Northwest, 1991-2016. Aquatic Mammals 44(3). doi: 10.1578/AM.44.3.2018.299
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