Research Document - 2006/052

Numbers of bowhead whales (Balaena mysticetus) in the eastern Canadian Arctic, based on aerial surveys in August 2002, 2003 and 2004

By Cosens, S.E., H. Cleator, and P. Richard

Abstract

In 2002, a three year program was begun to fly line transect surveys of bowhead whales summering in the Canadian eastern Arctic. The goals of the survey were to estimate numbers in both the putative Davis Strait-Baffin Bay (DS-BB) and Hudson Bay-Foxe Basin (HB-FB) stocks and to develop a better understanding of the summering distribution of these whales. In 2002, bowheads thought to belong to the DS-BB stock, were surveyed in Eclipse Sound, Prince Regent Inlet and Gulf of Boothia. In 2003, surveys were flown in southern Gulf of Boothia, Foxe Basin and northwestern Hudson Bay to estimate numbers in the putative HB-FB stock. A second 2003 survey estimated numbers of DS-BB whales summering along the east coast of Baffin Island. In 2004, Eclipse Sound and Admiralty Inlet were re-surveyed and parts of Barrow Strait were surveyed. Surface counts of bowheads were analyzed in DISTANCE and adjusted for whales not seen because they were diving. Adjustment factors for diving animals were derived using data collected from whales monitored with satellite-linked tags. An estimated 7,309 (95% CI = 3,161-16,900) bowheads occupied Eclipse Sound, Prince Regent Inlet and Gulf of Boothia in 2002. In 2003, 1,828 (95% CI = 940-3,554) bowheads were estimated in Admiralty Inlet and along the east coast of Baffin Island and an estimated 981 (95% CI = 319-3,018) whales occupied the southern Gulf of Boothia, Foxe Basin and northwestern Hudson Bay. Few whales were seen in the areas covered during the 2004 survey; not enough to produce an estimate. Recent results of satellite tracking studies and genetic analyses are consistent with a single population of bowheads in the eastern Canadian Arctic and west Greenland waters. As a result of this and to limit the possibility of counting individuals more than once, surveys results were not combined between years. The best partial estimate from the combined bowhead population is 7,309 (95% CI = 3,161-16,900). This is considered a partial estimate because it covered the Prince Regent Inlet-Gulf of Boothia-Eclipse Sound (PRI-GoB-ES) survey area, which is only part of the known summer range.

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