Killer Whales Find Prey in the Melting Arctic Bonanza Is A Bonanza


Research scientist Brynn Kimber of the National Oceanic and Atmospheric Administration’s Marine Mammal Laboratory at the University of Washington has spent a lot of time analyzing sound data recorded in icy waters in Alaska, Canada, and northern Russia. Typically, Miss Kimber hears the chatter of head whales, beluga whales, narwhals, and other marine mammals native to that area of ​​the Arctic.

A few years ago, they began to hear a distinctive cry that acousticians describe as similar to that of a grumpy house cat: the piercing call of a killer whale. Miss Kimber wondered at first if their ears were deceiving them.

“When I started, my mentor said to me, ‘You won’t see killer whales this far north,’ said Ms. Kimber. But as years of data accumulate and more orca searches are carried out in areas where they have never been recorded, it turns out that this is no longer true.

“I started to see more in the following years, where I had seen absolutely none of them in previous years,” Ms. Kimber said. “This was quite unusual.”

Orca calls are further evidence of a rapidly changing Arctic. As sea ice declines, killer whales, which are actually dolphins, are now entering once inaccessible parts of the sea and spending more time where they were once only occasionally spotted, data Ms Kimber presented on Thursday. Annual meeting of the Acoustic Society of America in Seattle.

As a result, some of nature’s most effective predators have greatly expanded the scope of their prey. The change has potentially important consequences for animals up and down the food chain, including humans.

arctic sea ice significantly decreased in the forty years since satellite tracking began. Amy Willoughby, a marine mammal biologist with NOAA’s Alaska Fisheries Science Center, said that in the past 15 years alone, roughly 75 percent of ice volume has been lost, and the remaining ice is thinner and of lower quality.

Ice loss combined with warming waters and atmospheric temperatures has affected every level of the Arctic ecosystem. Large mammals such as polar bears struggled to navigate the shrinking habitats as seaweeds at the bottom of the Arctic food chain bloomed. earlier and more abundant as usual.

In recent years, scientists have noticed a similar confusion in the behavior of marine mammals in the region. Orcas feast mostly on head whales. Scientists and Native Arctic communities recorded an increasing number Bowhead whale carcasses in the northeastern Chukchi and western Beaufort seas with signs of orca attack.

Even the presence of predators can have far-reaching consequences, even if the orca does not take a single bite. Bowhead whales are typically drawn to dense ice-covered blobs when threatened by orcas, which giant-skull bowheads lack the ability to break through frozen waters for air. The Inuit word “aarlirijuk” describes this head fear response developed specifically to escape killer whales.

However, as the ice retreats, these defense mechanisms can become a liability. Bowheads must spend more time than usual before hiding in thick ice where feeding opportunities are scarce. Calves that are not yet strong enough to break the ice may suffocate.

Any reduction in headstock numbers could also have consequences on the food chain: Whales are an important food source for subsistence hunters in Indigenous Arctic communities, Ms. Kimber said.

“Killer wheels are really clever,” said Cory Matthews, a research scientist with the Canadian Fisheries and Oceans Arctic region. “They consume really fast. If a new area opens up, maybe within the next year they can get in there and use a prey population that may be really slow to respond to these changes.”

He added that it may take years before scientists fully understand the long-term consequences of how these extremely deadly and newly emboldened predators expand their reach in the Arctic.



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