Application of a Bayesian hierarchical model to estimate trends in Atlantic harbor seal ( <scp> <i>Phoca vitulina vitulina</i> </scp> ) abundance in Maine, U.S.A., 1993–2018

The population of harbor seals (Phoca vitulina vitulina) along the coast Maine, U.S.A., has experienced rapid growth in abundance following passage Marine Mammal Protection Act 1972 but current information on trends is lacking. In this study, we apply a Bayesian hierarchical model to aerial survey data nonpups and pups. Prior 2001, estimates rates from 8-year moving averages reached high 2.1% 9.4% per year with posterior probabilities positive .97 >.99 for pups, respectively. Between 2001 2012, estimated decreased low −1.9% probability negative .95. 2012 2018, were close zero suggesting little change nonpups. Estimates pups between −2.5% 0.94 at end time series decrease pup 2018. total estimate 2018 61,336 (CV = 0.08).