The climate crisis means reduced levels of sea ice and the shorter time it remains covering the Arctic Ocean are combining to open up greater areas of open water to killer whales, new research reveals.
But scientists have warned that the growing presence of these intelligent predators could potentially create an ecological imbalance which would damage habitats and the species which live in them.
In recent years, scientists have increasingly tracked killer whales moving into the Arctic, where the animals are capable of teaming up to hunt larger prey such as seals, walruses, and even other species of whale.
A research team at the University of Washington which studied the animals using acoustic tools to find and track them, used eight years of data to reveal how the species is spending more time than ever before in the Arctic Ocean.
The scientists said the behaviour can also put the whales in danger, as rapid temperature falls can freeze the sea, leaving them at risk of ice entrapment.
The team said the change in the whales’ behaviour comes “directly following the decrease in sea ice in the area”.
Brynn Kimber, from the University of Washington, who led the research said: “It’s not necessarily that killer whales haven’t been reported in these areas before, but that they appear to be remaining in the area for longer periods of time.
“This is likely in response to a longer open water season.”
She noted that though there remains a high degree of variability, the September Arctic sea ice minimum is declining at an average rate of 13 per cent per decade, when compared to values from 1981 to 2010.
“Killer whales are being observed in the Chukchi Sea (in the Arctic Ocean) in months that were historically ice covered and more consistently throughout the summer,” she added.
The team said reduction in sea ice may have opened new hunting opportunities for killer whales if certain species of prey are unable to use the ice to avoid the highly adaptive predator.
They suggested the endangered bowhead whale may be particularly vulnerable to predation by killer whales, with the risk to this species likely to increase due to longer open water seasons.
The research is being presented to the Acoustical Society of America.
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