Beluga whale habitat selection and distribution in the Mackenzie Estuary and the Tarium Niryutait Marine Protected Area

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Noel, Aurelie
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The Eastern Beaufort Sea (EBS) beluga population migrates to the Mackenzie Estuary and to the Tarium Niryutait Marine Protected Area every summer and the reasons behind this selection are not fully understood. Once in the Estuary, beluga whales (Delphinapterus leucas) are harvested by Inuvialuit communities of the Inuvialuit Settlement Region for whom they represent an essential country food, contributing to their well-being. In the last decade, community members voiced their concerns and identified research priorities pertaining to belugas resources, baselines and habitats. To enhance our understanding of EBS beluga whale habitat and further anticipate effects of a changing climate, it was crucial to understand why belugas select these habitats. We created a habitat model based on aerial surveys observations from the late summer 2019 paired with remote sensing imagery to establish a baseline of environmental and spatial conditions selected by belugas. Then we assessed the baseline against historical data. We finally evaluated the habitat model with concurrent tagged observations to integrate the inferences made at a larger spatio-temporal scale. High turbidity and warm water temperatures were the two most important factors explaining beluga presence and were associated with the inshore waters of the Mackenzie River channels and along unprotected coastlines. Comparisons with past observations suggested that the observed beluga distribution had shifted from the baseline and was probably the results of the influence of changing environmental conditions on beluga response, either on a temporary (i.e., acclimatisation) or permanent basis (i.e., adaptation). The evaluation of the habitat model showed mixed results. The inferences of selection, created in combining quality of environmental conditions and belugas mechanisms of selection, explained the intertwined patterns of beluga habitat distribution. Those findings enhanced our understanding of EBS beluga ecology and highlighted the complexity in defining and predicting beluga habitat distribution. This complexity, by preventing an accurate assessment of the changing beluga habitat distribution, represents new challenges for harvesters that who may have to switch the timing and location of their harvest in response.
Beluga whale, Mackenzie Estuary, Habitat model, Habitat Selection, Resource Selection Function