Abstract

(…) Two separate predation events were documented off the coast of Vancouver Island, British Columbia between the years 2013-2014. Both predation events occurred on small cetaceans from the Phocoenidae family: (Phocoenoides dalli) and (Phocoena phocoena). These two species act as primary subjects of predation for one of three ecotypes of killer whale within the Pacific Northwest. Bigg’s killer whales, also known as transients, are the only known ecotype to actively prey on marine mammals (Baird and Dill 1995). The killer whales in this region belong to the inner west coast transients, comprising approximately 304 individuals (Ford et al. 2013). These whales occupy a range that extends from Northern Washington, along the coast of British Columbia, to Southeastern Alaska (Ford and Ellis 1999).

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The two porpoise’s allowed for a detailed analysis of transient killer whale hunting behaviour. A gross necropsy was performed on the two prey specimens at the Royal British Columbia Museum in Victoria, B.C. on November 25, 2014. The necropsy was led by Dr. Lynette Browne with assists from Josh McInnes, Kelsey Cullen, Annette Dehalt, and Dr. Gavin Hanke. Both specimens were examined for pre- and post-mortem injuries to provide evidence that the animals were killed by transient killer whales. (…)