Study tracks calls used by endangered Cook Inlet belugas, and human-made noise in their habitat

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.”


Also yet to be determined, she said, is whether Cook Inlet belugas are increasing the sound levels of their calls so they can be heard over the din of ship engines and other manmade noises. That behavior, known as the Lombard effect, does happen elsewhere, such as among belugas in eastern Canada’s St. Lawrence River, she said.

During the project, which used acoustic devices planted on the seafloor at two key sites in 2018 and 2019, Brewer and her partners heard plenty of other underwater noise. What is believed to be oil and gas activity sounded like “jingling or flushing” she said. There were occasional bursts from small boats’ outboard motors. Even airplane noise could be distinctly heard from the bottom of the inlet.

“I was really surprised when I started on this project,” Brewer said. “You can hear if it’s like a commercial plane coming into the airport or if it’s like a little prop plane and it really sounds like it does in air.”

There are also natural sounds, like calls from humpback or killer whales that may swim through, and the scratching and popping of ice, which is likely seasonal background noise to Cook Inlet belugas.

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For some environmentalists, the findings about ship noise are evidence that regulators need to do more to reduce effects on industrialization on Cook Inlet belugas, which federal scientists say numbered about 1,300 in 1979 but declined steeply after then.

The Center for Biological Diversity has been calling for a pause to issuances of incidental harassment authorization that allow operators in the inlet to accidentally disturb belugas and other Cook Inlet marine mammals. Those authorizations are granted under the federal Marine Mammal Protection Act, either by NOAA’s National Marine Fisheries Service or by the U.S. Fish and Wildlife Service, depending on the marine mammal species.

Under the act, the actions, known as “takes,” that are permitted through authorization can range anywhere from minor encounters that might cause a protected animal to have a slight physical reaction like a change in swimming direction to those that cause accidental animal deaths. The allowable takes depend on the type of authorization.

Some of the most recent authorizations issued for incidental harassment of Cook Inlet belugas and other inlet marine mammals were given in 2022 to Hilcorp for activities around a drill rig. The first authorization covered work until Sept. 14, 2023; and the second is valid until mid-September of this year. More recently, the National Marine Fisheries Service in January issued an incidental take authorization to the Port of Alaska for construction work.

The Hilcorp authorizations were issued over the objections of the Center for Biological Diversity and other organizations. In a petition submitted in 2022, the center asked NOAA’s National Marine Fisheries Service to stop issuing incidental harassment authorizations until it completes a study of the cumulative effect on the endangered beluga population.

“They’re allowing tens of thousands of these takes a year, and that’s just incredibly harmful,” said Cooper Freeman, Alaska representative for the Center for Biological Diversity. “And they have no idea what the cumulative effect of all that is.” Since most of the activities in the inlet do not require incidental harassment authorizations, a pause should not cause serious problems, Freeman said.

“The residents love Cook Inlet beluga whales and really care about these whales and want to see their recovery,” he said. “We think that the agency, by completing this cumulative analysis, can help meet their goal of recovering the belugas and get a better handle on all the impacts that are hindering their recovery.”

While authorizations issued over the past nine years allowed a cumulative 100,000 beluga takes, the actual number that occurred was far lower, according to a NOAA spokesperson. Virtually all the permitted takes in Cook Inlet have been for what is classified as minor disturbances not expected to cause harm, said agency spokesperson Julie Fair. Examples of allowable takes include research activities that support the agency’s Cook Inlet beluga recovery plan, she said.

Beyond the question of permitted takes, there is another way to reduce noise impacts to belugas and other whales: slower speed limits.

Brewer pointed to Washington’s Puget Sound as an example. There, in habitat for an endangered killer whale population, shippers are experimenting with slower vessel speeds. It is, for now, a voluntary program.

Additionally, a new state law that goes into effect next year creates a mandatory 1,000-yard vessel buffer there to protect the whales.

Noise disturbances have been at the center of concerns elsewhere in Alaska, including their potential effect on whales swimming in Arctic waters. There, climate change has reduced sea ice and expanded shipping opportunities.


A 2021 study by Canadian and U.S. scientists, including some from the University of Alaska Fairbanks and Alaska Department of Fish and Game, found that belugas and bowhead whales in the Chukchi and Beaufort seas are swimming in the same places where ship traffic is expected to increase. “Without proactive vessel management and effective mitigation measures, acoustic disturbance of whales is expected to increase, and eventually expand to more months of the year, as ship traffic continues to increase in step with increases in the length of the open water season,” the study said.

Originally published by the Alaska Beacon, an independent, nonpartisan news organization that covers Alaska state government.