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Beluga whale mystery: New genetic testing method finds answers

Published: Feb. 23, 2021 at 3:36 PM AKST
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ANCHORAGE, Alaska (KTUU) - It’s a mystery that scientists have tried for years to solve: Why is the population of Cook Inlet beluga whales continuing to decline? NOAA Fisheries says their numbers have dropped from a high of 1,300 to an estimated 280, even though they were granted protections under the Endangered Species Act in 2008.

“After subsistence hunting was mutually agreed upon to be ceased, we thought there would be a bounce-back for the animals...they haven’t recovered” said Verena Gill, a biologist with NOAA Fisheries in Anchorage. “To understand why, we need to understand how old are the animals in this population. Do we have an abnormally young population that can’t breed yet?”

Determining the age of Cook Inlet belugas has been a problem. Scientists often relied on examining their teeth, since they show growth rings, similar to trees. “Well, you cannot go out into the inlet and grab your local beluga whale, yank one of its teeth out and age it that way” said Gill. “First of all, they’d be pretty angry about it. Secondly, it’s pretty difficult. So, we have been limited to collecting teeth from animals that have discovered were deceased.”

To determine the age of living belugas, scientists are turning to a new genetic testing technique that requires small skin samples from the whales, which are collected using a dart gun. It’s a process that NOAA Fisheries says does not harm the animals.

The samples are checked for chemical changes in the whale’s DNA that occur over time, and the epigenetic process can determine the age of the animals.

Recently, the results of the new DNA sampling from a limited group of whales was compared to previously know data about whale pregnancies. Scientists could already tell if a female whale was pregnant, but they could not tell how old the mother was until the new DNA technique came along.

Paul Wade, who heads up NOAA’s Cook Inlet beluga whale research, says the preliminary results show older beluga females are reproducing, but younger females, in the 10-to-20 year age group, are reproducing at a rate of only 10%. “This is something we see in mammal populations that are not doing well. If they are food limited, it just takes them longer to become physically mature and they delay when they start having babies.”

Wade stressed that the results are preliminary, and that researchers are not giving up hope. “It is exciting to get these new tools that give us more insight into what’s going on in the population, so we are very pleased and excited to be able to study the whales in new ways” Wade said. “However, these little tidbits of information that we’re getting, that suggest that the population is not doing well, it is a great concern and it’s a little depressing from one point of view that we’re trying to study the whales and figure out what’s going on, but if we do discover that they’re not producing enough calves to recover, then that is a little bit of depressing news for us when we are working so hard to try to recover the population.”

Wade said tissue sampling last summer had to be canceled because of the pandemic, but he says researchers hope to be back on the water in July of 2021 to gather more samples that he hopes will provide additional insight into the whales’ recovery prospects.

“Discovering what happens in science takes a long time” said Gill. “Evolution takes a long time, science takes a long time. it takes a while to figure all of this out.”

NOAA Fisheries is asking Alaskans to become “citizen scientists” by taking part in the AK Beluga Monitoring Partnership. From mid-March to mid-May, groups of volunteers will gather at five locations around Cook Inlet to count beluga whales.

For information on how to sign up, go to https://akbmp.org/

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