Beluga survey aims to guide sustainable harvest

Earlier this summer, a group of scientists from NOAA spent hours in the air over the Norton Sound and Yukon River Delta, flying back and forth in careful east-west transects, looking for shiny white crescents on the surface of the water. They were counting belugas as part of longstanding co-management effort with Alaska Native hunters who rely on the whales for subsistence.

“Without an abundance estimate, it’s very difficult to know whether the beluga harvest is sustainable,” said Megan Ferguson, NOAA research biologist at the Alaska Fisheries Science Center in Seattle. During a Strait Science presentation last week hosted by UAF’s Northwest Campus, Ferguson shared some of the raw data she and her fellow researchers collected through their survey.

The eastern Bering Sea survey of belugas was requested by the Alaska Beluga Whale Committee, or ABWC, a group that includes subsistence hunters and formed in 1988 to conserve and manage whale populations in cooperation with NOAA’s National Marine Fisheries Service. Since its inception, the ABWC has initiated research on beluga populations to check their health and abundance.

“The ABWC gets a lot of credit for a lot of the research that’s been done on belugas in Alaska,” Ferguson said. Tom Gray, a hunter of Nome, who is now chairman of the ABWC, was the first to put a satellite tag on a beluga in the Norton Sound in 2012. Those tags have helped researchers understand where belugas move throughout the year. For instance, the population known as eastern Bering Sea belugas spends its summers mostly in the Norton Sound. They are genetically distinct from the other populations the ABWC manages in Bristol Bay, the eastern Chukchi Sea and the Beaufort Sea.

Beluga hunters have also helped scientists collect data on the diversity of beluga diets. Ferguson said that samples of beluga stomachs that hunters turned over to scientists between 1993 to 2012 contributed to a study that found at least 25 species of fish and 25 species of invertebrates, from saffron cod and Pacific herring to octopus and shrimp, all swallowed whole by belugas. “It’s a really broad spectrum of prey,” Frost said.

Ferguson reported that during eight survey flights that took place between June 24 and 30, 2022, the researchers flew 2,210 miles worth of transects and counted 821 belugas. The highest densities were observed closer to the coastlines, where belugas chase prey in silty water. Large groups of belugas seemed to congregate especially around Scammon Bay, where researchers counted groups with 67, 87 and 120 individuals.

Ferguson needs more time to crunch the numbers and produce a population estimate based on the number of belugas observed. During the last survey of this population in 2017, the researchers spent more time in the air, covering 5,336 miles, and they counted 1,897 belugas, which led to a population estimate of about 9,200.

The results of the survey could influence how ABWC manages whales in the region.

“We’re living in a fast-changing time,” ABWC chairman Gray told The Nome Nugget in an interview earlier this summer. “The whales aren’t changing. They’re using the same resource areas. But we are changing, and we’re learning how to be better hunters. We have better tools. So now we better start paying attention to what the resource is doing. We need the science world involved in counting whales and estimating the population. We know what our annual take is. So this survey is going to tell us how big [the population] is and how safe we’re managing these whales.”

Earlier this year, the ABWC released a draft management plan specifically for eastern Bering Sea belugas, intended as a proactive measure to keep the population healthy.

The draft plan includes a traffic light-style classification system for safe harvest levels. The harvest of belugas would be labeled “green” and considered sustainable if the number of whales lost over the previous three years is no more than 2.4 percent of the population abundance. This would be more no more than 220 whales if the population estimate remains 9,200.

The harvest would be labeled “yellow” if the average harvest over the previous three years rose to more than 220, or if the population estimate dropped to 8,800, a decline of 15 percent. In that case, actions to reduce harvest levels would be discussed by a team consisting of tribally appointed ABWC delegates from Norton Sound and the Yukon Delta, as well as regional delegates from groups such as Kawerak and the Association of Village Council Presidents. That team would also discuss the possibility of further scientific studies.

The harvest level would be labeled “red” and considered not sustainable if the average number of belugas lost over the previous three years rose to more than 280 whales, or three percent of the 2017 population survey. This label would also be slapped on if the abundance estimate declined to 6,500, representing a 30 percent population drop. In this case, the ABWC would recommend that the population survey take place more frequently and for harvesting levels to be reduced by up to 50 percent.

The plan is designed to avoid the type of crash other beluga populations around Alaska have experienced, explained Kathy Frost, a marine mammal biologist and longtime member of the ABWC.

“Cook Inlet belugas are endangered, Kotzebue Sound belugas are