Gray whale die off, bowhead whale population estimates are focus of annual NOAA survey

Gray whales feeding (Photo from NOAA)

ANCHORAGE (KTUU) - An annual survey of arctic marine mammals dating back four decades continues this summer with a focus on identifying the population size of bowhead whales and understanding the feeding behavior of gray whales.

The National Oceanic and Atmospheric Administration's Aerial Surveys of Arctic Marine Mammals project started in 1979 and has created a long-term data set for tracking changes of marine life in the Arctic.

For the first time in its history, the 2019 survey will expand into Canadian waters to determine a new abundance estimate of the Western Arctic population of bowhead whales.

Bowhead whales are an endangered species and are a staple of subsistence life for Alaska Native communities. The last abundance estimate of the species estimated the population at 16,820.

"If you compare that to the size at the end of commercial whaling which was in the mid 1900s, that population got down to about 1,000 or 3,000 animals," said Megan Ferguson, marine ecologist with NOAA. "So this population has really rebounded just over the course of the last 50 years or so."

Two groups of researchers will be stationed in the Arctic. Ferguson is with a group based in Deadhorse. Another group is based in Utqiagvik.

Researchers follow specific flight routes until they come to a group of bowhead whales. When they find a group, the plane increases its elevation so that they do not disturb the animals and circles around the whales to observe their behavior.

In addition to the requirement to track the species due to its status as an endangered species and the importance of knowing the abundance for subsistence harvesting, Ferguson says the changing environment in the Arctic makes the need for a new population estimate timely.

"These surveys started in the late 1970s as a way to monitor the marine mammals as human activity started to increase and arise in the Arctic," Ferguson said. "A third interest is that there is increasing interest in having activities occur in the Arctic. With sea ice diminishing, there's going to be more vessel traffic up there. It could be shipping traffic, there might be fisheries that are expanding into that area, there could be more military work going on up there, and so these data that we collect give a baseline of where these animals are in this changing environment."

In addition to the bowhead population estimate, the researchers are also working to document the behavior of gray whales in their summer feeding grounds.

In May, NOAA declared an Unusual Mortality Event after large numbers of gray whales were found dead along the West Coast from Mexico to Alaska.

As of July 18, NOAA says 189 dead gray whales have been found on the Pacific Coast, including 28 in Alaska. Experts have previously told Channel 2 News that most whales, especially those that are emaciated, sink when they are dead. That fact, in addition to the thousands of miles of sparsely populated coastline along Alaska suggest that the actual number of dead gray whales is significantly higher.

"The Northeastern Chukchi and the Eastern Chukchi Sea in general is an important feeding area for gray whale, and this year we're taking extra effort to collect data that can inform the unusual mortality event investigation," Ferguson said. "Specifically, we're taking more photographs of live whales as they're foraging, and we're also making sure to take pictures of any gray whale carcasses that we see."

The team executing NOAA's aerial survey is part of an international task force comprised of federal agencies and university researchers studying the gray whale die off.

"Are we seeing really skinny animals, or do they look like they're fat and happy? And because the researchers that are collaborating with this all up and down the United States West Coast and in Canada, we can see if there are any changes geographically that way," Ferguson said.

In addition to the specific research on bowhead and gray whales, the aerial surveys will also document polar bears, walruses and other mammals, as well as take sea ice imagery.

The project is funded by the Bureau of Ocean Energy Management and runs through October.

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