Combining multiple data sources to model population dynamics of Eastern Canada-West Greenland bowhead whales

The Eastern Canada-West Greenland (EC-WG) bowhead whales ( Balaena mysticetus ) were heavily harvested from 1530 to 1915, and the population was depleted to commercial extinction. Obtaining reliable estimates of abundance through aerial surveys can be challenging due to the vast area that needs to be covered. To overcome this, a Brownian bridge movement model (BBMM) was used with data obtained from satellite-tagged bowhead whales. The BBMM allowed the calculation of the probability of occupancy both inside and outside areas surveyed during aerial surveys conducted in 1981, 2002 and 2013. Using a Quasi-Poisson regression, the relationship between the probability of occupancy and abundance in surveyed areas was established. This relationship was then used to extrapolate survey estimates into unsurveyed areas. Extrapolated estimates were included with genetic mark-recapture abundance estimates from 2013 to 2017 and harvest history into a Bayesian stock production model to recreate population dynamics post-commercial whaling, 1915–2022, and project 10 years into the future under various harvest levels (0, 10, 20, 30 whales). The model estimated a 2022 population of 8147 (95 % CI 6152-10,825) whales, and an initial population (N 1915 ) estimate of 817 (95 % CI 225–4194) whales. Calculating the likelihood of population decline indicated probabilities ranging from 12 to 31 % after a 10-year period across all harvest levels. The findings of the model suggest that EC-WG bowhead whales have been consistently recovering following the cessation of commercial whaling and have already surpassed the point of maximum productivity, leading to a slowdown in growth in recent years. • Used occupancy modelling to update EC-WG bowhead whale abundance estimates. • Population trajectory and future harvest effects were modelled using updated estimates. • Population is approaching carrying capacity, growth will likely plateau. • Continued monitoring required to track effects of harvest into the future.