Bowhead whale carcasses in the eastern Chukchi and western Beaufort seas, 2009-2017
Amy Willoughby, Janet Clarke, Megan Ferguson, Raphaela Stimmelmayr, and Amelia Brower
International Whaling Commission
Bowhead whale (Balaena mysticetus) carcass data and imagery provide insights into the health of the species. The Aerial Surveys of Arctic Marine Mammals (ASAMM) project surveys large areas of otherwise inaccessible offshore bowhead whale habitat in a relatively short period of time. ASAMM offers a long time series of consistent information on floating and beach-cast bowhead whale carcasses detected during standardized line-transect surveys. A total of 27 carcasses identified as bowhead whale were documented from 2009 to 2017. Twenty-one carcasses (78%) were found floating and six were beach-cast (22%). Highest number of carcasses were observed in 2015 (10/27), followed by 2013 (6/27), and 2016 (5/27). Carcasses were distributed across the eastern Chukchi (EC) and western Beaufort (WB) sea study areas from 141.6°W to 168.1°W and 68.9°N to 72.0°N. More bowhead whale carcasses were seen in the EC study area; September had the highest number of bowhead whale carcass sightings in both EC and WB study areas; and September had the most survey effort, but October had the highest bowhead whale carcass sighting rates. Bowhead whale carcasses having injuries consistent with killer whale predation were photo-documented in one carcass in 2017, two carcasses per year in 2012, 2013, and 2015, and three carcasses in 2016. Three of the bowhead whale carcasses documented by ASAMM were likely calves or yearlings: one each in 2013, 2015, and 2017. Each of the calf/yearling carcasses was photographed and showed signs of killer whale interactions. Prior to 2012, evidence of killer whale predation on bowhead whales was not recorded in the ASAMM database or carcass imagery. Two carcasses, one in 2013 and one in 2015, were likely whales struck and lost during aboriginal subsistence hunting activity; this is based on timing, proximity to known struck and lost whales, and image review of those carcasses. One carcass in 2015 had gear attached (orange buoy and attached line) that was consistent with commonly used subsistence whaling equipment.