Killer whale predatory scarring on mysticetes: A comparison of rake marks among blue, humpback, and gray whales in the eastern North Pacific

Abstract

AbstractWe investigated the predator–prey relationship between baleen whales and killer whales by observing predatory scarring (rake marks) on the tail flukes of three mysticete species from the eastern North Pacific Ocean: humpback, blue, and gray whales. We integrated both qualitative scores and new quantitative measures to compare predatory scarring left by killer whales on the three species. We found statistically significant interspecies differences in incidence, location, and accumulation rates of scarring. Gray whales showed a higher incidence of predatory scarring compared to the other two species. Humpback and gray whales bore most of their rake marks on the trailing edge of the tail fluke, while blue whales showed more evidence of predatory scarring on the leading edge of the fluke, potentially consistent with previously hypothesized theories of flee versus fight responses to killer whales for different mysticete species. Of whales with scarring, blue whales were twice as likely to suffer from fluke mutilation compared to humpback and gray whales. Humpback and gray whales were also significantly more likely to accumulate new rake marks over the years compared to blue whales. We examine how these differences provide insight into the prey‐specific hunting behavior of killer whales.