Durban JW, Matkin CO, Ellifrit DK, Andrews RD, Barrett-Lennard LG

Quantifying a stopover of killer whales preying on gray whales rounding the Alaska Peninsula

Predation by killer whales is being increasingly reported on recovering populations of baleen whales, but there have been no direct quantitative assessments of its impact. Durban and colleagues show that stopover duration and annual abundance of mammal-eating killer whales around the Alaska Peninsula in spring correlated with abundance of gray whale calves, their primary prey. The presence of killer whales increased through May into early June, when satellite tags tracked northerly movements into the Bering Sea, and as far as 1620 km into the Chukchi Sea, likely following migrating gray whales. These data indicate focused and prolonged predation by killer whales on a recovered population of large whales and highlight the importance of predation in influencing killer whale population dynamics and structuring.

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