Arctic | Mammals
Estimating Pacific walrus abundance and survival with multievent mark-recapture models Presenter: William Beatty , wbeatty@usgs.gov
Patrick Lemons , patrick_lemons@fws.gov Jason Everett , jason_everett@fws.gov Cara Lewis , cara_lewis@fws.gov Rebecca Taylor , rebeccataylor@usgs.gov
Robert Lynn , robert.lynn@usda.gov Suresh Sethi , suresh.sethi@cornell.edu Lori Quakenbush , lori.quakenbush@alaska.gov, Alaska Department of Fish and Game - Arctic Marine Mammal Program John Citta , john.citta@north-slope.org, North Slope Borough Michelle Kissling , kissling.michelle@gmail.com Arctic marine ecosystems are undergoing rapid physical and biological change associated with climate warming and loss of sea ice. Sea ice loss will impact many species through altered spatial and temporal availability of resources. In the Bering and Chukchi Seas, the Pacific walrus Odobenus rosmarus divergens is one species that could be impacted by rapid environmental change, and thus, population assessments are needed to monitor changes in the status of this ecologically and culturally important marine mammal. We conducted a 5 yr genetic mark−recapture study to estimate demographic parameters for the Pacific walrus. We developed a Bayesian multievent mark−recapture model to estimate walrus survival and abundance while accounting for age misclassification. We estimated the probability of juvenile annual survival as 0.63 (95% credible interval [CrI]: 0.39−0.87) and adult female annual survival as 0.90 (95% CrI: 0.74−1.00). We estimated total abundance as 257 193 (95% CrI: 171138−366366). We provide the first estimate of total Pacific walrus abundance since an aerial survey in 2006, which generated a substantially less precise total population size estimate (129 000; 95% CI: 55000−507000). The emerging ecosystem state in the northern Bering and Chukchi Seas will likely result in a decline in Pacific walrus abundance, but there is substantial uncertainty regarding the magnitude of the anticipated decline. Our demographic estimates provide critical information to evaluate future population trends of this subsistence resource vital to communities that border the Bering and Chukchi Seas in the USA and Russia. Natalia Kryukova , nkryukova@gmail.com John Wenburg , john_wenburg@fws.gov
Alaska Marine Science Symposium 2023 81
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