Photo-identification of Antarctic blue whales: new data from 1998 and 2015-2018
Paula A. Olson, Marijke de Boer, Amy Kennedy, Michael C. Double, Koji Matsuoka, Luis A. Pastene, Ken Findlay
International Whaling Commission
Newly available collections of identification photographs of individual Antarctic blue whales were compared to the images of 441 individuals in the Antarctic Blue Whale Catalogue. The sources of photographs include the IWC IDCR/SOWER cruises in 1989/1990, 1993/1994, and 1997/1998, and opportunistic photographs collected by collegial scientists, naturalists, and tourists 2015-2018. Seventeen new individual blue whales were identified: 4 from the SOWER cruise in 1998 and 14 from the opportunistic photos. There were no matches between any of the newly identified whales or to the Antarctic Catalogue. The 17 new identifications brings the total number of photo-identified Antarctic blue whales up to 458 whales, represented by 342 left sides and 332 right sides. The minimum (332) and maximum (458) number of unique individuals represents 15% and 20%, respectively, of the most recent accepted estimate of abundance of Antarctic blue whales, 2,280 in 1997/1998 (Branch, 2007). All 17 of the new identifications came from IWC Management Areas underrepresented in the catalogue, Areas I and II. The collection of Antarctic blue whale identification photographs provide data for capture-recapture estimates of abundance as well as information on the movement of individual blue whales within the Antarctic region.