Individual-based energetic model suggests bottom up mechanisms for the impact of coastal hypoxia on Pacific harbor seal (Phoca vitulina richardii) foraging behavior

For larger seals, English sole was the most optimal prey during normoxia, however during moderate to severe hypoxia Pacific sand lance was the most beneficial prey. For smaller seals, Pacific herring was the most efficient prey species during normoxia, but sand lance became more efficient as hypoxia increased. Sand lance represented the highest increase in foraging efficiency during severe hypoxic events for all seals. Results suggest that during increasing hypoxia, smaller adult harbor seals could benefit by shifting from foraging on larger neritic schooling fishes to foraging closer inshore on less energetically-dense forage fish. Larger adult seals may benefit by shifting from foraging on groundfish to smaller, schooling neritic fishes as hypoxia increases. The model suggests a mechanism by which hypoxia may result in increased foraging efficiency of Pacific harbor seals, and therefore increased rates of predation on coastal fishes on the continental shelf during hypoxic events.