Song production by the eastern North Pacific right whale, Eubalaena japonica

Abstract

This paper describes unique, stereotyped, gunshot songs produced by the eastern North Pacific right whale (NPRW, Eubalaena japonica). Four unique songs were documented over eight years (2009–2017) and five separate locations in the southeastern Bering Sea. Similar to songs reported for other species, each NPRW song consists of a hierarchical structure of 1-3 different repeating phrases comprised predominantly of gunshot calls (though other call types were occasionally present). Songs were detected every year from July through early January. All four song structures remained consistent over eight years. Two different songs often occurred simultaneously; the same song never occurred simultaneously at the same location. However, the detection of the same song on the same day and time at two locations 310 km apart indicates multiple animals can produce the same song. These songs were localized to individual male NPRWs using directional sonobuoys; it remains unknown if females also sing. We hypothesize that these songs may be a reproductive display similar to song in other mysticetes. Although singing has not been documented in congeneric right whale species, songs presented here fit the classification of song attributed to other cetacean species. Possible functions of these songs and their management implications will be discussed.