Acoustic Occurrence and Affiliation of Fin Whales Detected in the Northeastern Chukchi Sea, July to October 2007–10
Fin whales are common throughout the North Pacific region, particularly in the Gulf of Alaska and the Bering Sea, even though these areas were heavily depleted by decades of whaling. Whalers also took fin whales in the southwestern Chukchi Sea, but only five sightings have been reported for the entire Chukchi Sea in the past 30 years. Large-scale arrays consisting of 26 – 44 bottom-mounted acoustic recorders were deployed in the northeastern Chukchi Sea from July to October in 2007 to 2010. Fin whales were detected off Cape Lisburne and Point Lay in 2007, 2009, and 2010. Large interannual variations in the number of acoustic detections may be related to environmental conditions. Calls detected during summer months consisted primarily of irregular sequences. Stereotyped sequences, called songs, were also detected at the end of the recording period in 2007 and 2010. Their structure matched that of one of the songs recorded in the Bering Sea, suggesting that only one of the stocks occurring in the Bering Sea extends its range into the northeastern Chukchi Sea. These detections currently represent the northernmost fin whale records in the North Pacific region.