Distribution and Abundance of the Eastern Canada – West Greenland Bowhead Whale Population Based on the 2013 High Arctic Cetacean Survey

Thomas Doniol-Valcroze,Jack W Lawson,Natalie C Asselin,Daniel G Pike,Kevin J Hedges,Steven H Ferguson,Jean-François Gosselin

doi:10.7557/3.5315

Abstract

The hunting of bowhead whales (Balaena mysticetus) is an integral part of Inuit culture. An up-to-date abundance estimate of the entire Eastern Canada – West Greenland (EC-WG) bowhead population is necessary to support sustainable management of this harvest. The High Arctic Cetacean Survey (HACS) was conducted in August 2013, primarily to update abundance estimates for known stocks of Baffin Bay narwhal (Monodon monoceros). As the ranges of narwhal and bowhead largely overlap, the survey area was expanded to cover the summer range of bowhead whales. Bowhead whale abundance was estimated using 3 aircraft to cover the large survey area within a short time frame. Distance sampling methods were used to estimate detection probability away from the track line. Double platform with mark-recapture methods were used to correct for the proportion of whales missed by visual observers on the track line (perception bias). Abundance in Isabella Bay, an area known for high bowhead density, was estimated using density surface modelling to account for its complex shape and uneven coverage. Estimates were corrected for availability bias (whales that were not available for detection because they were submerged when the aircraft passed overhead) using a recent analysis of satellite-linked time depth recorders transmitting information on the diving behaviour of bowhead whales in the study area in August of the same survey year. The fully corrected abundance estimate for the EC-WG bowhead whale population was 6,446 (95% CI: 3,838–10,827). Possible sources of uncertainty include incomplete coverage and the diving behaviour of bowhead whales. These results confirm earlier indications that the EC-WG stock is continuing to recover from past overexploitation.

Highlights

Bowhead whales (Balaena mysticetus) (Figure 1) are iceassociated baleen whales with a nearly circumpolar Arctic distribution
Abundance in Isabella Bay, an area known for high bowhead density, was estimated using density surface modelling to account for its complex shape and uneven coverage
This single Eastern Canada – West Greenland (EC-WG) population was historically overharvested by commercial whalers (Higdon, 2010) and the Committee on the Status of Endangered Wildlife in Canada recommended in 2009 that it be listed as a Species of Special Concern under the Species At Risk Act (COSEWIC, 2009)

Summary

Introduction

Bowhead whales (Balaena mysticetus) (Figure 1) are iceassociated baleen whales with a nearly circumpolar Arctic distribution. Evidence from genetics and satellite telemetry studies (Dueck, Hiede-Jørgensen, Jensen, & Postma, 2006; Postma, Dueck, Heide-Jørgensen, & Cosens, 2006) indicate that bowhead whales from the Eastern Canadian Arctic are part of a single population that is shared with West Greenland. This single Eastern Canada – West Greenland (EC-WG) population was historically overharvested by commercial whalers (Higdon, 2010) and the Committee on the Status of Endangered Wildlife in Canada recommended in 2009 that it be listed as a Species of Special Concern under the Species At Risk Act (COSEWIC, 2009). A limited subsistence hunt resumed in the Nunavut Settlement Area in 1996 and in the Nunavik Marine

Methods

Results

Conclusion