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Humpback whale abundance in the North Pacific estimated by photographic capture‐recapture with bias correction from simulation studies
Author(s) -
Barlow Jay,
Calambokidis John,
Falcone Erin A.,
Baker C. Scott,
Burdin Alexander M.,
Clapham Phillip J.,
Ford John K. B.,
Gabriele Christine M.,
LeDuc Richard,
Mattila David K.,
Quinn Terrance J.,
RojasBracho Lorenzo,
Straley Janice M.,
Taylor Barbara L.,
Urbán R. Jorge,
Wade Paul,
Weller David,
Witteveen Briana H.,
Yamaguchi Manami
Publication year - 2011
Publication title -
marine mammal science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.723
H-Index - 78
eISSN - 1748-7692
pISSN - 0824-0469
DOI - 10.1111/j.1748-7692.2010.00444.x
Subject(s) - abundance (ecology) , mark and recapture , humpback whale , sampling (signal processing) , population , abundance estimation , sampling bias , statistics , right whale , fishery , whale , geography , biology , ecology , demography , sample size determination , mathematics , physics , sociology , detector , optics
We estimated the abundance of humpback whales in the North Pacific by capture‐recapture methods using over 18,000 fluke identification photographs collected in 2004–2006. Our best estimate of abundance was 21,808 (CV = 0.04). We estimated the biases in this value using a simulation model. Births and deaths, which violate the assumption of a closed population, resulted in a bias of +5.2%, exclusion of calves in samples resulted in a bias of −10.5%, failure to achieve random geographic sampling resulted in a bias of −0.4%, and missed matches resulted in a bias of +9.3%. Known sex‐biased sampling favoring males in breeding areas did not add significant bias if both sexes are proportionately sampled in the feeding areas. Our best estimate of abundance was 21,063 after accounting for a net bias of +3.5%. This estimate is likely to be lower than the true abundance due to two additional sources of bias: individual heterogeneity in the probability of being sampled (unquantified) and the likely existence of an unknown and unsampled breeding area (−8.7%). Results confirm that the overall humpback whale population in the North Pacific has continued to increase and is now greater than some prior estimates of prewhaling abundance.