UW researchers decipher beluga calls to bolster conservation efforts

“Cook Inlet belugas swimming in northern Cook Inlet, near Anchorage, Alaska. Photo: Arial Brewer Alaska’s Cook Inlet was home to nearly 1,300 beluga whales in the late 1970s, but today the population hovers around 300. Despite almost two decades of recovery work, the whales aren’t bouncing back. The Cook Inlet belugas are likely struggling under multiple pressures, including increasing human noise. Researchers are working on deciphering whale-whale communication to better account for the impact of noise on this vulnerable population. In a new study, University of Washington scientists eavesdropped on Cook Inlet belugas, recording more than 1,700 calls representing 21 different behavioral encounters. This work builds on a 2023 study showing that noise from commercial shipping, the primary industry in the region, masks common beluga calls. Although many marine mammals rely more on sound than sight, our understanding of acoustic communication among these animals is limited. Beluga whales use vocalizations to socialize, stick together and avoid danger. The new study, published May 7 in Behavioral Ecology and Sociobiology , investigated the behavioral, social and environmental contexts in which the whales produce various calls. “We knew that human-generated noise was masking their calls, but we didn’t know what those calls were used for,” said Arial Brewer , a UW doctoral student in aquatic and fishery sciences. “This study gave us important insights into the world of beluga communication and how it is disrupted by industry and development.” They found that Cook Inlet belugas use a specific type of call — a combined call — when calves are present. Combined calls were one of the call types that got drowned out by shipping noise in the 2023 study, suggesting that shipping noise could be disrupting communication with calves. If mothers and calves can’t remain in contact, it could spell trouble for the young whales. Cook Inlet beluga mother and calf in Eagle Bay, Alaska. Photo: Arial Brewer “We don’t have the data to directly connect noise and calf separation,” Brewer said, “but if a mother whale can’t acoustically keep in contact with her calf, that could be a huge problem.”. Researchers also found that calling between whales increased right before a behavioral change in the group, such as a transition from socializing to traveling, and when the tide was coming in. The call rate for individual whales decreased as group size increased, suggesting that individuals call less in a big group, perhaps to avoid talking over each other. In Cook Inlet, where the whales live year round, silty glacial water gets churned up by powerful currents and dramatic tides. Beluga whales likely moved in after the last ice age, roughly 10,000 years ago. Vocal communication and echolocation, a navigational strategy used by bats and some whales, have allowed them to survive in this extreme environment, but human noise presents a newer challenge. “Their main foraging hot spots for salmon are in the northern part of the inlet, near Anchorage, and in close proximity to the airport, the Port of Alaska, and the military base. I think there are ways to adapt but it’s tricky for them and noise pollution is far from the only threat,” Brewer said. Beluga whales in the St. Lawrence Estuary in Eastern Canada — also very noisy — have evolved to communicate at very high frequencies , perhaps in response to lower frequency anthropogenic noise. They also make their calls louder when it’s noisy, just like two people conversing at a party would. In the Puget Sound region, where the endangered Southern Resident killer whales live, large ships are asked to slow down when whales are reported in the area. Smaller ships are legally required to keep their distance and slow down within half a mile of the whales. This program was introduced after researchers demonstrated that shipping noise interferes with hunting . “The Port of Alaska could explore similar strategies to mitigate the impact of industry,” Brewer said. “We can’t halt shipping, but we’re trying to understand what we can do to manage these critical habitats, especially when the animals are nearby.” Co-authors include Amy Van Cise , a UW assistant professor of aquatic and fishery sciences; Sarah Converse , a UW professor of aquatic and fishery sciences; Andrew Berdahl , a UW assistant professor of aquatic and fishery sciences; Manuel Castellote , a research scientist in the UW Cooperative Institute for Climate, Ocean, & Ecosystem Studies; Kimberly Goetz of NOAA; Christopher Garner and Andrea Gilstad of the Air Force Conservation Department. This study was funded by UW School of Aquatic and Fishery Sciences, the Cooperative Institute for Climate, Ocean, and Ecosystem Studies under a NOAA Cooperative Agreement, and the H. Mason Keeler Endowed Professorship in Sports Fisheries Management. For more information, contact Brewer at arialb@uw.edu .

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