Conservation physiology of Arctic cetaceans: Using endocrine techniques to measure stress in beluga and bowhead whales in the Canadian Arctic

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Hudson, Justine
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Conservation physiology is a field of study that focuses on physiological changes in response to human activity and environmental change, including elevations in stress hormones, changes in metabolism, and declines in reproductive hormones, body condition and immune function. Physiological changes such as these can indicate environmental pressures and be used to monitor the health of wildlife populations. In this study, I analyzed endocrine data of two Arctic cetaceans, the Western Hudson Bay beluga population and the Eastern Canada-West Greenland bowhead whale population to better understand how they may respond to climate change. In Chapter 2, I demonstrated, for the first time, that it was possible to collect blow samples from free-swimming beluga whales and that cortisol and urea concentrations could be reliably measured in beluga blow samples. Urea was found to be an unsuitable dilution marker to normalize blow samples. Absolute cortisol concentrations were influenced by sample device, quantity rating, and age class, while urea concentrations were only influenced by sample device. In Chapter 3, I determined baseline triiodothyronine (T3) and corticosterone concentrations measured from baleen plates collected from bowhead whales and conservatively concluded that bowhead whales foraged year-round, based on a lack of observed seasonal variation in T3 and a lack of correlation between T3 and stable isotope values. Interestingly, we found a strong positive correlation between T3 and corticosterone in each whale, which requires further investigation. This research provides important baseline information about Arctic marine mammal endocrinology and establishes key recommendations for carrying out physiological studies.
Arctic, Marine mammal, Endocrinology, Blow, Baleen, Glucocorticoid, Thyroid hormone