Vocalizations of common minke whales (Balaenoptera acutorostrata) in an eastern North Pacific feeding ground

The minke whale (Balaenoptera acutorostrata) is a small species of baleen whale with a cosmopolitan distribution. Despite extensive study on the vocalizations of other balaenopterids, the acoustic repertoire of minke whales is not well known. Individuals of the North Pacific subspecies (B. acutorostrata scammoni) produce unique vocalizations ('boings') during their putative breeding season from fall to spring. However, no vocalizations have been previously reported for this subspecies in any eastern North Pacific feeding ground. We present two call types recorded in the presence of six minke whales, two of which were confirmed as female, in Cormorant Channel, British Columbia, Canada, during the summer of 2012. The calls consist of downsweeps and pulse chains. These call types share some characteristics with calls described elsewhere, although they are not identical to similar call types observed for other populations. Calling rates for minke whales in this study region are very low compared to those reported for this subspecies on its putative breeding grounds, as well as for other subspecies on their feeding grounds. We propose predation risk, sexual segregation and acoustic masking as potential causes of the low calling rates observed for minke whales in Cormorant Channel.