Beluga Whales: Tagging Reveals Deep Dives and Foraging Habits

Improved tagging technology has allowed researchers to monitor the foraging patterns of beluga whales up close for the first time. It appears that two distinct populations of these whales dive upward of 900 meters to find enough Arctic cod to feed their families.

"This study gives us a benchmark of the distribution and foraging patterns for these two beluga populations," lead author Donna Hauser, a doctoral student in the University of Washington's School of Aquatic and Fishery Sciences, said in a news release. "However, there still needs to be additional work to see how beluga behavior has changed in concert with changing sea ice conditions in the Arctic."

Researchers analyzed tracking data of 30 belugas collected in the Arctic in the general vicinity of Alaska over the past 15 years. Their data revealed that both beluga populations winter in the Bering Sea, then travel north into the Beaufort and Chukchi seas as sea ice melts in the summer. Arctic cod, researchers say, largely drives this migration. Furthermore, as belugas take to the ocean bed to find food, they base the depths of their dives on sea floor topography.

"They were likely looking for opportunities to eat based on where prey was concentrated by oceanographic features," Hauser added.

Beluga whales are notoriously difficult to study, as they spend most of their time underwater and out of reach in harsh Arctic environments. Advanced technology, however, allowed researchers to tag whales that got close to shore in the early summer. The tags were designed to turn on when whales surfaced to breathe, in turn transmitting location and depth measurements to a satellite, and would remain on the whales for up to 18 months.

Researchers suggest their findings, recently published in the journal Marine Ecology Progress Series, hold great importance for understanding how climate change alters the migration and feeding patterns of Arctic marine life.

"The results of this work can be used not only to understand ecological relationships for Arctic top predators but also inform the management of beluga whales, which are an important subsistence resource for northern communities," co-author Kristin Laidre, a UW assistant professor of aquatic and fishery sciences, concluded in the university's release.

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