| Summary: | Many populations of cetaceans are still recovering from the impacts of whaling and face ongoing, and sometimes increasing, human stressors. However, due to their slow reproductive life history, monitoring trends and responses to potential threats requires long-term datasets. Understanding the status of cryptic species, like beaked whales, is further challenged by their remote habitat, low density and deep diving ability, restricting opportunities for data collection. Northern bottlenose whales (NBW, Hyperoodon ampullatus) were previously whaled and, although the Scotian Shelf population is currently recognized as Endangered under the Species at Risk Act (SARA), their population structure as well as their status in Canada are unclear. The goal of my thesis was to reassess evidence for NBW population structure, life history and threats using a diversity of methods to integrate long-term datasets and address questions broadly relevant to the conservation of beaked whales. I began with a systematic review and metanalysis of the literature on cetacean population structure with particular consideration of studies of odontocetes. I applied genetics to distinguish evolutionarily significant population structure and historical demography of NBW in Canada and stable isotopes to estimate the period of maternal care. Using photoidentification I reviewed the stability of marks and quantified the rate of anthropogenic scarring. I modelled the change in cumulative human impacts over 30 years to evaluate concurrent trends in estimates of NBW abundance and spatial conservation measures. I found that, despite having almost the lowest genetic diversity of any cetacean, Scotian Shelf NBW were distinct from those in other areas, supporting their management as a Designatable Unit under SARA. However, their recovery from whaling has likely been impacted by their low reproductive potential, and despite few reports, ongoing threats of entanglement. Encouragingly, long term trends indicate that the reduction of human activities on the Scotian Shelf has contributed to the population’s recovery. My results demonstrate how the life history and past exploitation of NBW have left them vulnerable to ongoing impacts, and suggest that protecting important habitat can be an effective conservation tool for beaked whales.
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