A decade of humpback whale abundance estimates at Bermuda, an oceanic migratory stopover site

We constructed annual abundance of a migratory baleen whale at an oceanic stopover site to elucidate temporal changes in Bermuda, area with increasing anthropogenic activity. The North Atlantic humpback whales visiting Bermuda between 2011 and 2020 was estimated using photo-identification capture-recapture data for 1,204 whales, collected December 2009 May 2020. Owing sparse set, we combined Cormack-Jolly-Seber (CJS) model, fit through maximum likelihood estimation, Horvitz-Thompson estimator calculate used stratified bootstrap resampling derive 95% confidence intervals (CI). accounted heterogeneity detection sighting rates via catch-effort model and, guided by goodness-of-fit testing, considered models that transience. A incorporating modified effort time-varying transience selected (corrected) Akaike’s Information Criterion (AICc). survival probability non-transient animals 0.97 (95% CI 0.91-0.98), which is comparable other studies. rate increased gradually from 2018, before large drop 2019. Abundance varied 786 individuals 593-964) 2016 1,434 924-1,908) 2020, non-significant linear increase across the period interannual fluctuations. These estimates confirm importance migrating should encourage review cetacean conservation measures Bermudian waters, including area-based management tools. Moreover, line time series presented here, regional be updated facilitate population monitoring over entire range.