Research Document - 2009/116

Information relevant to the identification of Critical Habitats of North Pacific Humpback Whales (Megaptera novaeangliae) in British Columbia

By L.M. Nichol, R. Abernethy, L. Flostrand, T.S. Lee, and J.K.B. Ford

Abstract

This report presents a synthesis of published and unpublished information on the occurrence and distribution of Humpback Whales in British Columbia waters, and particularly in four areas of the coast; 1) the waters surrounding Langara Island; 2) coastal waters along the south eastern side of Moresby Island and Kunghit Island; 3) the mainland channels around Gil Island and Gribbel Island: and 4) waters off southwest Vancouver Island including Barkley Sound, La Perouse Bank, Swiftsure Banks and Barkley Canyon. The annual seasonal occurrence of Humpback Whales observed in these four areas over more than a decade, disproportionate number of sightings in these areas compared to other coastal areas and the historic occurrence of Humpback Whales evident from whaling records indicate that Critical Habitat designation is warranted. Waters off Langara and southeast Moresby islands appear to support over half of the British Columbia population, while the area off southwest Vancouver Island may support a distinct sub-group occurring primarily in southern British Columbia and Washington State. The Gil Island area is the only fjord habitat identified as candidate Critical Habitat. Although it is not yet possible to quantify habitat characteristics that are important to Humpback Whales, it is most likely that important attributes of these areas for Humpback Whales are oceanographic processes that concentrate prey. These processes include tidal mixing, eddies, upwelling, wind- and wave- driven currents and bathymetric features that aggregate euphausiids and forage fish. Considering the precautionary approach is required to address recovery of threatened species, and that analysis of data from these four areas utilized the best information currently available, it appears that all four candidate areas meet the criteria for designation as Critical Habitat under Canada’s Species at Risk Act. It is expected that the candidate areas of Critical Habitat identified in this document comprise a portion of total Critical Habitat for the species, and that in future additional regions of critical and important habitat may be identified both in Canada and in other jurisdictions.

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