Bowhead whale Balaena mysticetus diving and movement patterns in the eastern Canadian Arctic: implications for foraging ecology

Abstract

The bowhead whale Balaena mysticetus is the only mysticete species endemic to the Arctic. The Eastern Arctic-West Greenland (EA-WG) population is considered of special concern in Canada as these whales remain at risk of becoming threatened or endangered due to their slow rate of growth and low fecundity, and ongoing environmental changes in the Arctic. In this context, we used satellite-linked time-depth recorders (SDR-T16) to investigate their movements and dive behaviour and identify plausible summer feeding areas in the Canadian Arctic. Seven individuals from the northern Foxe Basin (FB) (n = 4 in July 2003) and Cumberland Sound (CS) (n = 3 in July 2006) were tracked by satellite for 17 to 293 d. Movement patterns from 4 whales were analyzed using a hidden Markov model (HMM) to inform the probability of whales being in one of 2 behavioural modes: transient or resident. Comparing dive characteristics during transient and resident periods, we observed that the Gulf of Boothia (GB) with moderate ice coverage (54−62%) was used as a summer foraging area by all 4 whales even though they came from different regions. All animals transited rapidly through Fury and Hecla Strait, an area of heavy ice coverage (80−98%). Whales spent most of their time at shallow depths (8−16 m) regardless of time of day when in resident mode, likely feeding on near-surface aggregations of zooplankton. Considering the apparent importance of the GB as a feeding area for this population, every effort should be made to maintain the integrity of this ecosystem.