Survival Rate and 2011 Abundance of Bering-Chukchi-Beaufort Seas Bowhead Whales From Photo-identiï¬cation Data Over Three Decades
Givens, G., Mocklin, J., Brattstrom, L., Tudor, B., Koski, W., Zeh, J., Suydam, R., George, J.
International Whaling Commission
New photo-identiï¬cation data were collected from a 2011 aerial survey of Bering-Chukchi-Beaufort Seas bowhead whales. We scored and matched these images to existing images from 1985, 1986, 2003, 2004, and 2005. Other interyear comparisons between this set of years were also conducted to generate a complete matching matrix for the 6 years. These data were used to estimate bowhead survival rate and population abundance using Huggins models embedded in a Robust Design capture-recapture analysis. Our estimated survival rate was 0.996 with approximate lower conï¬dence bound 0.976, which is consistent with previous estimates and with research showing that bowhead lifetimes can be very long. Estimated 2011 abundance was 21,391 (CV=0.214, 95% CI 14,119 to 32,407). Although much less precise than the 2011 ice-based abundance estimate (16,820 with CV=0.052, 95% CI 15,176 to 18,643) of Givens et al. (2016), the 2011 photo-id estimate adds to the evidence that the stock is abundant, increasing from previous years, and unlikely to be harmed by limited subsistence hunting.