Capture-recapture estimates of abundance of Antarctic blue whales
Paula A. Olson, Douglas Kinzey, Michael C. Double, Koji Matsuoka, Luis A. Pastene, Ken Findlay
International Whaling Commission
Photo-identification data of Antarctic blue whales from 1990/91 to 2014/15 were used in a capture-recapture analysis to produce estimates of super-population abundance for the circumpolar Antarctic. An estimate for IWC Management Area III 1992/93 to 2013/14 was also produced. Photographs were collected during IWC, IWC-SORP, ICR, and SAABWS cruises and also made available by opportunistic contributors. The circumpolar estimates are 4,629 (95% CI 2,563 to 8,558) Antarctic blue whales (left side photographs) and 4,485 (95% CI 2,514 to 8,192) (right side photographs) for the years 1990/91 to 2014/15. These estimates show improved precision with the addition of 30% more photo-ID data than was available for a previous capture-recapture study based on data from 1992/93 to 2008/09. Estimates of abundance for Area III are 1,944 (95% CI 903 to 4,390) (left side photographs) and 2,575 (95% CI 1,089 to 6,380) (right side photographs). As more data become available in the future, the reliability of capture-recapture estimates should improve.