Baleen whales are not important as prey for killer whales Orcinus orca in high-latitude regions

摘要: Certain populations of killer whales Orcinus orca feed primarily or exclusively on marine mammals. However, whether not baleen represent an important prey source for is debatable. A hypothesis by Springer et al. (2003) suggested that overexploitation large industrial whaling forced to prey-switch from pin- nipeds and sea otters, resulting in population declines these smaller mammals the North Pacific southern Bering Sea. This prey-switching part contingent upon idea commonly attack mysticetes while they are high-latitude areas. In this study, we used photographic sighting data long-term studies 24 regions worldwide determine proportion bear scars (rake marks) whale attacks, examine timing scar acquisition. The results study show there con- siderable geographic variation with rake marks, ranging 0% >40% different regions. every region, great majority seen were present whales' bodies when animals first sighted. Less than 7% (9 132) scarred humpback multi-year histories acquired new after sighting. suggests most attacks target young animals, probably calves their migration low-latitude breeding calving areas feeding grounds. Overall, our imply adult high latitudes, therefore one primary assumptions underlying (and its purported link whaling) invalid.