|
|||||
|
|
Humpback whale abundance in the North Pacific estimated by photographic capture‐recapture with bias correction from simulation studies |
|
| Authors: | Jay Barlow John Calambokidis Erin A Falcone C Scott Baker Alexander M Burdin Phillip J Clapham John K B Ford Christine M Gabriele Richard LeDuc David K Mattila Terrance J Quinn II Lorenzo Rojas‐Bracho Janice M Straley Barbara L Taylor Jorge Urbán R Paul Wade David Weller Briana H Witteveen Manami Yamaguchi |
| Institution: | 1. NOAA, National Marine Fisheries Service,Southwest Fisheries Science Center,3333 N. Torrey Pines Court,La Jolla, California 92037, U.S.A.E‐mail: jay.barlow@noaa.gov;2. Cascadia Research Collective,218 1/2 W. 4th Avenue,Olympia, Washington 98501, U.S.A.;3. Marine Mammal Institute and Department of Fisheries and Wildlife,Oregon State University,Newport, Oregon 97365, U.S.A.;4. Kamchatka Branch, Pacific Institute of Geography,Russian Academy of Sciences,Partizanskaya, 6, Petropavlovsk‐Kamchatsky, 683000, Russia;5. NOAA, National Marine Fisheries Service,Alaska Fisheries Science Center,7600 Sand Point Way N.E.,Seattle, Washington 98115, U.S.A.;6. Fisheries and Oceans Canada,Pacific Biological Station,3190 Hammond Bay Road,Nanaimo, British Columbia V9T 6N7, Canada;7. Glacier Bay National Park,1 Park Road,Gustavus, Alaska 99826, U.S.A.;8. NOAA, National Marine Fisheries Service,Southwest Fisheries Science Center,3333 N. Torrey Pines Court,La Jolla, California 92037, U.S.A.;9. Hawaiian Islands Humpback Whale National Marine Sanctuary,726 South Kihei Road,Kihei, Hawaii 96753, U.S.A.;10. Juneau Center, School of Fisheries and Ocean Sciences,University of Alaska Fairbanks,17101 Pt. Lena Loop Road,Juneau, Alaska 99801 U.S.A.;11. Instituto Nacional de Ecología,c/o CICESE,Km. 107 Carretera Ensenada‐Tijuana,Ensenada, Baja California 22860, Mexico;12. University of Alaska Southeast,1332 Seward Avenue,Sitka, Alaska 99835, U.S.A.;13. Universidad Autonoma de Baja California Sur,Ap. Post 19‐B,La Paz, Baja California Sur 23081, Mexico;14. University of Alaska Fairbanks,117 Trident Way,Kodiak, Alaska 99615, U.S.A.;15. Ogasawara Marine Center,Byobudani, Chichijima, Ogasawara‐mura,Tokyo 100‐21, Japan |
| Abstract: | 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. |
| Keywords: | humpback whale Megaptera novaeangliae North Pacific abundance photo‐identification capture‐recapture bias simulation model |