TORONTO – Melting sea ice in the Arctic Ocean has paved the way for killer whales to spend more time in these waters, but researchers fear it could threaten prey in these areas and potentially upset the ecosystem.
Researchers at the University of Washington used underwater microphones to track the movement of water species off the west and north coasts of Alaska between 2012 and 2019 presented their results at an Acoustical Society of America conference Thursday.
The researchers didn’t want to focus on killer whales at first, but were surprised to see more and more orcas migrating to these waters.
“Our work mainly focuses on studying the migration patterns of species through the Bering, Chukchi and Beaufort Seas based on acoustic presence or absence,” lead author Brynn Kimber said in a press release.
“But when I was looking for other species, like beluga whales, I saw more and more killer whales in areas where I wasn’t expecting them. That motivated me to take a closer look at our orca records. “
Killer whales had usually stayed away from these waters to avoid ice inclusions – which occurs when ice prevents the whales from coming to the surface to breathe – but the effects of climate change mean the sea is ice-free for longer periods of time.
“It’s not necessarily that killer whales have never been reported in these areas, but they appear to have been in the area for long periods of time,” said Kimber. “This is likely a response to a longer open water season.”
Kimber added that September sea ice in the Arctic Ocean has declined at an average rate of 13 percent per decade since the 1980s.
Several prey species, such as the endangered bowhead whale, have exploited the sea ice to evade predators from killer whales, but the declining sea ice offers orcas a new abundant food source that could destroy these prey at risk.
“These results suggest a changing Arctic, both in terms of the presence of killer whales themselves and in terms of the impact that increased killer whale predation could have on the Arctic food web,” the authors write.