Abstract
Walruses (Odobenus rosmarus) are exploited for subsistence purposes in West Greenland. However, current information about the abundance of walruses subject to harvest in eastern Baffin Bay subject to harvest has been unavailable despite being critical for maintaining sustainable catch levels. Three visual aerial surveys were conducted in 2006 (21 March to 19 April 2006), 2008 (3 to 12 April) and 2012 (24 March to 14 April) to estimate the number of walruses on the wintering grounds in eastern Baffin Bay and Davis Strait. Data on the fraction of walruses that were submerged below a 2m detection threshold during the surveys were obtained from 24 walruses instrumented with satellite-linked-time-depth-recorders in northern Baffin Bay in May-June 2010-2012. An availability correction factor was estimated at 36.5% (cv=0.08) after filtering of data for an observed drift of the pressure transducer of more than 2.5 m. The surveys resulted in walrus abundance estimates that were corrected for walruses submerged below a detection threshold and for walruses that were missed by the observers. The estimates of abundance were 1,105 (cv=0.31, 95% CI 610-2,002) in 2006, 1,137 (0.48, 468-2,758) in 2008 and 1,408 (0.22, 922-2,150) in 2012.
Highlights
In Baffin Bay and Davis Strait walruses (Odobenus rosmarus) winter on banks located between 66o30′N and 68o15′N along West Greenland
In this paper we report on the abundance of walruses in eastern Baffin Bay and Davis Strait based on aerial surveys conducted during March and April in 2006, 2008 and 2012
The difficulties include the fact that they have a clumped distribution, they occur in two different habitats with different detection probabilities, they have variable group sizes and availability correction factors that are difficult to obtain simultaneously with the survey
Summary
In Baffin Bay and Davis Strait walruses (Odobenus rosmarus) winter on banks located between 66o30′N and 68o15′N along West Greenland. Their occurrence in this area is due to the availability of shallow water (
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