Taken from the newsletter Portrait de baleines, no 14, September 14, 2018

H824 is a humpback whale that is easy to spot, thanks to its uniquely patterned tail flukes. Its tail is mostly white, with the exception of the centre (where the two lobes meet), where one can observe a black section that fades as it moves away from the centre. Four smaller white spots mark the middle of this spot. Its left fluke is “clipped” at the tip, and rake marks can be seen on the tip of the right fluke (first identified in 2016). These marks are the result of a killer whale attack. The tips of its two flukes are completely white, bordered by a wavy black outline. It also shows an X on its left lobe. The Mingan Island Cetacean Study (MICS) first sighted H824 with its mother Quill in 2015 (the year it was born). This year, Quill was photo-ID’d by GREMM research assistants on September 1.

Killer whales most often go after calves and not adults. Killer whale attacks on baleen whales in the northwest Atlantic are evident by the parallel lines left by the teeth of these predators. These marks are especially present on the pectoral fins and the tail, which killer whales grip in order to control their prey. Attacks on calves occur mainly during their first migration to the feeding grounds from their warm-water birthing grounds. Generally the northward migration begins when the calves are just a few months old.

Some studies suggest that killer whale predation on baleen whales may have contributed to the evolution of migration in these species. The breeding grounds of humpbacks are generally far away from killer whale feeding areas. In the case of adults, killer whales rarely hunt large rorquals such as blue whales, humpbacks or fin whales, but they can on occasion. Killer whales, however, seem to prefer smaller marine mammals (calves, minke whales, dolphins, pinnipeds, etc.) and these preferences vary depending on where the individuals are and which population they belong to. Some have a penchant for minke whales while other populations prefer to feed on seals or sea lions. Additionally, not all killer whale populations feed on marine mammals; some populations feed exclusively on fish. In British Columbia, the Resident Killer Whales feed almost exclusively on a single species, the king salmon (or chinook salmon), even if other species such as sockeye salmon are more abundant.