Characterization of legacy persistent organic pollutants (POPs) in northern bottlenose whales of the western north-Atlantic

Northern bottlenose whales (Hyperoodon ampullatus) are a medium sized toothed whale of the North Atlantic. Two Canadian populations exist, one along the Scotian Shelf (“The Gully”; Endangered) and the other around Baffin Bay. The objective of this study was to characterize the concentrations and patterns of persistent organic pollutants (POPs) in northern bottlenose whales as related to sex, location, and sampling year. Samples from a stranded individual allowed opportunistic analysis of blubber stratification of POPs. Concentrations of POPs in northern bottlenose whales were similar to other toothed whales in the North Atlantic. Contrary to most marine mammals, levels of dichlorodiphenyltrichloroethane (DDT) were higher than polychlorinated biphenyls (PCBs), suggesting a local source of DDT in the region. Females were found to have lower blubber concentrations of most POPs compared to males due to reproductive offloading. Levels of POPs were also typically higher in Scotian Shelf compared to Arctic animals. Full-depth blubber analysis revealed higher concentrations and proportion of less recalcitrant POPs in the inner blubber relative to middle and outer sections. Future monitoring of these populations would benefit from greater sample sizes, more consistent temporal sampling, and complimentary analysis of biogeochemical tracers to decipher aspects of feeding ecology and habitat use.