How beluga whales in Alaska’s Cook Inlet could be less stressed during COVID-19

By Bella Swart, UW Daily

Following 9/11, researchers measured a significant decrease in stress-increasing hormones in North Atlantic right whales. Due to less ship and air traffic in that area, there was less noise in the water than usual. This brought to attention the correlation between human created noise and high chronic stress levels in whales.

With the current global pandemic, there has been a similar decrease in air and ship traffic. Manuel Castellote and Arial Brewer, both researchers at the Joint Institute for the Study of Atmosphere and Ocean (JISAO), have taken advantage of this opportunity to measure the possible decrease of stress levels in the Cook Inlet beluga whale (CIBW) population.
“We know underwater noise creates a problem for this population of belugas,” Castellote said. “In fact, it’s been identified by the NOAA as one of the three main threats for the lack of recovery of this population. The Cook Inlet beluga population has been identified as one of the key endangered species for recovery.”

Brewer explained that once, there were as many as 1,300 belugas in the Cook Inlet.

“The current range, we think, is about 250 to 317 animals,” Brewer said.

This is due to a combination of a long past of subsistence hunting, a very anthropogenically affected habitat, and salmon population declines.

Belugas use sonar located in their “melons” — the enlarged parts of their heads that make them so distinguishable — in order to navigate and hunt for food.

“It’s a mechanism to generate a signal, a very short, impulsive signal, that travels in the water and then it bounces back from whatever is in front of the whale … and then they receive that echo and process the echo, and then they can see with sound in the water,” Castellote said.

The water in Cook Inlet is murky, making it more important that the whales are able to use their echolocation capabilities without any interruptions.

“It’s not just a matter of intensity, it’s also a matter of time exposed to that noise,” Castellote said. “If they are exposed to noise that is not very high, in the long run you might have immune responses. So if you have a lower immune system, more stress, and lower reproduction success, the calves may not be successful, there’s not good lactation, and therefore the animals aren’t surviving.”

In order to record the belugas, Castellote and Brewer have acoustic recorders on mooring packages around the mid-upper inlet that record year-round.

“With those same recordings, we can hear those whales, so we know if they are vocalizing in a different way, either using areas that were not used in the past in this time of year, because maybe the noise was pushing them away from it,” Castellote said. “So we can look at these recordings and how they use their habitat by their acoustics only.”

To collect physiological information and measure the cortisol hormone levels in the whales, which are related to stress, another team takes biopsies.

“The reaction isn’t very strong,” Castellote said. “The whales flap their tail or dive and then, in a few seconds, they’re back to their normal behavior. It’s like a little sting.”

The question is whether this current noise decrease will be enough to gain conclusive research. According to the researchers, it’s still unclear because of how slowly things happen.

“There’s definitely going to be a decrease in noise,” Castellote said. “What is not so clear is if that decrease is enough to show drastic changes in their physiology.”

Brewer further explained the big picture about their research.

“The goal of what we do as beluga researchers is trying to figure out what’s a good middle ground that the economy can still grow, but we’re not completely driving these animals to extinction,” Brewer said.

Castellote agreed with Brewer’s sentiment around helping the whales.

“In the end, it’s a fight against losing more diversity in the Arctic,” he said. “This is an example of how us as humans could be smart enough to find a solution in time to prevent this extinction. We need to find ways to coexist.”