February 29, 2024 — For the first time, the underwater calls made by the endangered beluga whales in Southcentral Alaska’s Cook Inlet have been recorded, identified and cataloged.
To accomplish that, University of Washington Ph.D. student Arial Brewer spent thousands of hours listening to the noises captured from audio devices planted on the seafloor. The result was a catalog of 18 distinct calls used by the belugas, which were a mixture of whistles and pulsed calls.
And, importantly for the belugas’ conservation, there is now evidence that those calls might be getting drowned out by noises from the commercial ships that ply the marine waters of Alaska’s most populous region, according to a study led by Brewer that details the findings.
Commercial ships are the dominant noise source in the inlet, “the most prevalent and just lasted the longest,” Brewer said. “Commercial ship noise can last for hours and hours.”
Brewer, in addition to her Ph.D. studies, works at the National Oceanic and Atmospheric Administration’s Alaska Fisheries Science Center. That agency and the Alaska Department of Fish and Game were partners in the study.
Cook Inlet belugas, which number about 330 animals according to the most recent estimates, are among the world’s 21 beluga populations. Only a few have had their calls recorded and cataloged, so that raises questions about the specificity of the 18 Cook Inlet calls that Brewer found.
“Whether those are completely unique to Cook Inlet or they just haven’t been described in other populations, we don’t know for sure,” she said. But it would be logical to think that the Cook Inlet calls are geographically distinct because the beluga population there has been isolated for 10,000 years, she said. “So, you know, ecologically, I think it makes sense.”