Characterization of population structure in northern bottlenose whales (Hyperoodon ampullatus) in the North Atlantic from an analysis of microsatellite data

The objective of this genetic analysis was to better understand northern bottlenose whale (NBW, Hyperoodon ampullatus) population structure and viability across the North Atlantic using microsatellite data from 60 contemporary specimens not previously available. Tissue samples were collected by biopsy from the Scotian Shelf, the Davis Strait – Labrador Sea, Jan Mayen near Iceland, and from a stranding in southern Newfoundland between 2014-2019. A total of 55 unique individuals were identified, expanding the current genetic dataset of NBW specimens to 218 individuals (1967-2019). Population structure analyses were consistent with site fidelity, as individuals resampled at different time periods were from the same geographic region. We detected a low number of unique microsatellite alleles in contemporary samples (2017-2019, n = 29) from the Davis Strait – Labrador Sea relative to historical samples (1971, n = 78), consistent with population reductions from harvesting and genetic drift. Population structure analyses supported three distinct genetic groups: the Scotian Shelf, the western North Atlantic (Davis Strait, Labrador Sea, West Iceland), and Jan Mayen (East Iceland). The differentiation of contemporary samples from Jan Mayen to other regions has not yet been reported, highlighting the importance of adequate size and distribution of samples for detecting subtle population structure in NBW.