Research Document - 2006/072

An Assessment of Critical Habitats of Resident Killer Whales in Waters off the Pacific Coast of Canada

By Ford, J.K.B.

Abstract

Two populations of fish-eating killer whales, northern residents and southern residents, inhabit waters off Canada’s west coast. These populations are listed as threatened and endangered, respectively, under the Species-at-Risk Act (SARA) because of their small sizes, recent declining population trends, and the vulnerability of their habitat and food supply to anthropogenic impacts. As required by SARA, a Killer Whale Recovery Team was assembled to develop a recovery strategy for resident killer whales, which was recently completed in draft form. Although the Team was able to define a number of recovery objectives and approaches, it was unable to identify in sufficient detail areas of critical habitat, as required in the SARA recovery process. This report describes analyses of published information and unpublished data undertaken in order to better define patterns of movements and habitat use by resident killer whales, and proposes two areas – one for each of the two resident killer whale populations – that appear to meet the requirements for designation as critical habitat under SARA. Two additional areas are described that are clearly of seasonal importance to northern residents and are identified as potential critical habitat. These areas are all situated on important migratory corridors for chinook salmon, the preferred prey species of resident killer whales. Seasonal occurrence of whales in these habitats is strongly associated with salmon abundance and foraging is the primary activity undertaken there. Other important life processes, including resting, socializing, mating, and, for northern residents, beach rubbing, are also undertaken in these areas. Additional critical habitats likely exist for resident killer whales, but further studies, particularly in remote areas and in winter to early spring, will be needed for their identification.

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