Orcas are expanding their territory and have moved into Arctic waters as climate change melts sea ice. Two genetically distinct populations have been identified by Canadian scientists.
Posted at 6:57 a.m.
Ninth Shen
The Canadian Press
However, their study says this could have “serious consequences” for potential prey whales, such as belugas, narwhals and bowhead whales, which lead researcher Colin Garroway called “slow, plump and delicious.”
Mr. Garroway, an evolutionary geneticist at the University of Manitoba, said in an interview that the situation is complex: Arctic orcas have the potential to disrupt ecosystems as apex predators, although they deserve to be preserved.
The study says orcas could also affect humans, “adding downward pressure on Arctic food webs critical to the social and economic well-being of northern communities.”
She says orcas in the eastern Canadian Arctic have been observed preying primarily on belugas and narwhals, followed by bowhead whales and seals.
We think there's going to be a big change in the structure of the community and how these different creatures interact.
Colin Garroway, principal investigator of the study
The study claims that the Arctic is the fastest warming region on the planet, and that as sea ice retreats, its waters are opening up to traditionally subarctic species, such as orcas.
Mr Garroway said orcas were once considered infrequent visitors to the Arctic because they risked breaking their famous dorsal fins on the ice.
But sightings have become more frequent.
Mr. Garroway said researchers took tissue samples from the orcas “and we were very surprised to find that there are actually two very distinct populations.”
“I said to myself: I didn’t believe it, and then I dug and dug and… it’s quite simple to do when you have the data. And, of course, there were two distinct populations,” Garroway said, adding that they numbered in the hundreds.
The study, published in Global Change Biology in June, described one group as “genetically distinct globally,” while the second is similar to Greenland's orcas.
Mr. Garroway said the two groups of Arctic orcas have different feeding behaviors and vocalizations and do not recognize each other as potential mates.
Hundreds of thousands of belugas, narwhals, bowheads, sperm whales and beaked whales live in the territories of Arctic orcas, he noted.
“Now that there's no more ice cover, we think that's one of the reasons the orcas are coming,” Garroway said.
There are all these slow, chubby, delicious whales in the Arctic that are easier to catch than not… It's interesting to see more orcas in the Arctic, and as top predators, they can disrupt the ecosystem.
Colin Garroway, principal investigator of the study
The study highlights that orca prey species are “culturally and economically important to indigenous communities, so these species also deserve to be preserved and managed in light of orca populations moving into the Arctic.”
Mr Garroway said that during the research period, which lasted several years, the team heard from indigenous groups in northern communities who expressed concerns about orcas roaming and hunting for food which is “crucial » for their communities.
“That's what makes this so confusing, because the orcas themselves are an endangered population and everything is changing,” Garroway said.
Mr Garroway said research was ongoing and there was still little known about the ecology of Arctic orcas, including where they go during the winter when the seas freeze. Following them was difficult.
“We've had a number of orcas with transmitters on, but it seems the longest takes us right to the edge of the Arctic and then turns off,” Garroway said.
“We don’t know where these whales go when they’re not in the Arctic… there’s a lot to learn.” »
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