Research Document 2017/004
Distribution, movements and habitat fidelity patterns of Fin Whales (Balaenoptera physalus) in Canadian Pacific Waters
By L.M. Nichol, R.M. Abernethy, B.M. Wright, S. Heaslip, L.D. Spaven, J.R. Towers, J.F. Pilkington, E.H. Stredulinsky, and J.K.B. Ford
Abstract
Fin Whale distribution and habitat use in northern waters of British Columbia (BC) were investigated using a multi-scale study approach based on data collected by Fisheries and Oceans Canada’s Marine Mammal Research Section. Ship-based survey data were used to model Fin Whale distribution as a function of habitat features in Hecate Strait and Queen Charlotte Sound and the results indicate that Moresby Trough and Greater Caamaño Sound were predicted to have the highest densities of whales. Photo-identification data were used to assess movement and site-fidelity of individual Fin Whales, and to estimate abundance. There was little indication of movements between the inshore region of Hecate Strait and Queen Charlotte Sound and the offshore region of Canadian Pacific waters, although there was more photo-identification effort applied to the inshore region. The overall abundance of Fin Whales present in the Hecate Strait and Queen Charlotte Sound region (including Greater Caamaño Sound) at any one time during the study period (2009-2014) was estimated to be 405 Fin Whales (coefficient of variation, CV = 0.6, 95% CI = 363-469), based on a photo-identification mark-recapture model. Analysis of satellite-linked telemetry tags using State-Space-Switching modelling indicated that tagged Fin Whales (n=19) remained in the area of Hecate Strait and Greater Caamaño Sound for the duration of their tag transmissions and exhibited extended periods of Area-Restricted-Search (ARS) movement behaviour which may represent foraging behaviour. Analysis of satellite-linked dive tags (n=6) indicated that during periods of ARS movement, dives were deeper during the day (70.1 ± 52.1 m SD) than at night (24.9 ± 17.4 m SD) and likely represented foraging behaviour. Tagged Fin Whales, particularly in Caamaño Sound, where most of the dive tags were deployed, dove consistently to depths likely associated with dense day-time zooplankton layers.
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