Killer whales (Orcinus orca) predation on mysticetes in the Gulf of California, Mexico

Abstract

Killer whales (Orcinus orca) prey on various whale species in the world’s oceans. Here, we present seven cases of mysticetes preyed upon by killer whales on the continental coast of the Gulf of California. Five fin whales (Balaenoptera physalus), one Bryde’s whale (B. brydei), and one gray whale (Eschrichtius robustus) were preyed upon and partly consumed in the same way over 17 years in different areas of the coast of Sonora, Mexico. The methodology included direct inspection of stranded or floating whale carcasses, analysis of predation marks, and review of videos provided by local fishermen. The notorious way in which whales were preyed upon by cutting and ripping large portions of blubber and skin layers is similar to how the whalers used to flense whale carcasses. No internal organs were consumed, although the tongue was consumed in each event. Most attacks occurred in shallow waters, coinciding with high productivity/upwelling areas. These events provide evidence on killer whales’ hunting behavior and consumption patterns, highlighting the importance of shallow waters and selectivity of the skin/blubber and tongue as preferential food, which contributes to understanding the trophic interactions of cetaceans in the Gulf of California.