Passive acoustic survey of bowhead whales in the Chukchi Sea.

Abstract

Western Arctic bowhead whales (Balaena mysticetus) transit through the Chukchi Sea in spring and fall during their seasonal migration between their winter grounds in the Bering Sea and their summer feeding grounds in the Beaufort Sea, where their presence is well documented. Comparatively little is known about their use of the Chukchi Sea in summer and winter. Here results are presented from a long-term passive acoustic monitoring program using a multi-recorder array deployed from late July 2007 through July 2008 in this area. Bowhead calls were recorded intermittently between August 2007 and January 1, 2008 and again from May 27, 2008 until the end of the study. Of particular interest is the detection of songs in late fall–early winter, which had previously only been recorded during the northward spring migration. They were compared to songs recorded off West Greenland during the previous mating season and found to be different. This is the first evidence of geographic variation of bowhead songs. Overall these detections provide new information on bowheads’ spatiotemporal use of the Chukchi Sea. The successes of the study also highlight the effectiveness of autonomous underwater acoustic recorders for marine mammal surveys in remote locations.