Large numbers of marine mammals winter in the Nort

Authors: M P HeideJørgensen MH S Sinding N H Nielsen A RosingAsvid R G Hansen

Publish Date: 2016/01/08

Volume: 39, Issue: 9, Pages: 1605-1614

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Abstract

The importance of the North Water polynya in Smith Sound as an overwintering area for marine mammals has been questioned One way to address the issue is to assess the abundance of selected marine mammals that are present during winter in the North Water Visual aerial surveys involving double observer platforms were conducted over the eastern part of the North Water polynya in April 2014 Four species of marine mammals were included in stripcensus estimation of abundance Perception bias was addressed using a doubleplatform survey protocol a Chapman mark–recapture estimator for whales seals and walruses Odobenus rosmarus on ice and a mark–recapture distance sampling estimation technique for walruses in water Availability bias was addressed by correcting abundance estimates by the percentage of time animals detected in water that were available for detection at the surface The resulting estimates suggested that 2544 walruses 95  CI 1513–4279 6005 bearded seals Erignathus barbatus 95  CI 4070–8858 2324 belugas Delphinapterus leucas 95  CI 968–5575 and 3059 narwhals Monodon monoceros 95  CI 1760–5316 wintered in the eastern part of the North Water polynya in April 2014 The walrus estimate is larger than previous summer estimates and it emphasizes the importance of the habitat along the Greenland coast as a walrus wintering ground The estimate of belugas is likely negatively biased due to the partial coverage of the potential habitat The estimate of narwhals is large compared to the few previous observations of narwhals in winter in the North Water and it demonstrates that large numbers of narwhals winter there The overall conclusion is that the North Water is indeed an important wintering area for at least walruses belugas narwhals and bearded sealsThis study was funded by the Greenland Institute of Natural Resources The North Water Project NOW funded by the Velux Foundations and the Carlsberg Foundation covered part of the writing costs Randall Reeves is gratefully acknowledged for providing comments to an earlier version of the paper

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