Environmental and biological factors affecting beluga whale (Delphinapterus leucas) movement and distribution in Hudson Bay
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Date
2022-04-29
Authors
Westdal, Kristin
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Abstract
Beluga whales (Delphinapterus leucas) are an Arctic cetacean with circumpolar distribution. They are known to have distinct, lengthy and consistent migration paths to and from summer and wintering grounds. The Western Hudson Bay beluga population, the largest summering aggregation in the world, inhabits three main estuaries in the summer season. Little protection is afforded to them here, and little is known of the specific details of their summer distribution and factors affecting that distribution. Using a combination of satellite telemetry, aerial photos, satellite data, and visual observations and historical reports, investigations into factors affecting beluga distribution in Western Hudson Bay were conducted. An examination into beluga age class distribution near the Churchill and Seal River estuaries, using aerial survey imagery, suggested that belugas may not be segregating by age in summer, however the Seal River estuary may be more important from a calf-rearing perspective. Belugas use a greater home range than we would expect, based on historical range data, in the face of predation by their main predator, the killer whale (Orcinus orca). Killer whales are sighted more frequently in Hudson Bay than historically, and results presented here show that ice entrapments, occurring with higher frequency in the future, may impact distribution of beluga as killer whales expand their range and occurrence in Hudson Bay. Finally, an assessment of beluga behaviour in the presence of whale-watching vessels showed that beluga response to vessels varied but the probability of travelling behaviour was significantly greater with distance from vessels; belugas also appear to be spending more time interacting with vessels now, as compared to 15 years ago when there were fewer whale-watching vessels. The results found through this research are useful in informing climate change implications, marine-protected area boundaries, policy and marine spatial planning, and subsistence harvest management.
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Keywords
beluga whale, Hudson Bay, Delphinapterus leucas, Distribution, Climate change