With Sea Ice Melting, Killer Whales Move Into the High Arctic

For Fisheries and Oceans scientist Steve Ferguson, this is another chapter in a multifaceted story. With climate change warming the Arctic faster than any other place on Earth, reducing summer sea ice almost entirely in some regions, killer whales, which have a global range, are beginning to colonize — rather than just periodically visit — one of the few places in the world they could not historically access.

“With sea ice retreating in the Arctic very rapidly, killer whales are finding new pathways to enter regions like Hudson Bay and the High Arctic,” said Ferguson. “Along with the polar bear, they have become the top predator in the region.” But while rapid sea ice retreat has diminished polar bear numbers by as much as 50 percent since the 1980s in regions like western Hudson Bay, the change has only benefited killer whales.

The fact that there are killer whales in the Arctic shouldn’t be surprising. A century ago, whalers sometimes spotted orcas around the fringes of the Arctic in North Atlantic waters, undoubtedly following some of the estimated 18,000 bowheads and tens of thousands of belugas and narwhals that existed at the time. None of them would have been a match for killer whales, who approach from all sides in highly coordinated attacks, biting and ramming their prey until there is little life left in them.

Back then, the killer whales were reluctant to follow prey into icy chokeholds during breakups, perhaps for fear of injuring their enormous dorsal fins. It didn’t mean that they did not occasionally try.

Several years ago, Inuit elder Solomon Qanatsiaq recalled seeing killer whales trapped in ice in Foxe Basin, at the north end of Hudson Bay, in the 1950s. He was just a boy then but remembers how much excitement it caused because killer whales were so rarely seen.

Ferguson got interested in orcas in the Arctic sometime around 2005, when colleague Jack Orr and scientists from Greenland and the U.S. confirmed previous Inuit reports of orcas hunting bowhead, beluga, and narwhal in the High Arctic. While capturing and tagging narwhal at the north end of Baffin Island, where orcas were rarely seen, they saw a pod of 12 to 15 orcas kill several narwhals.

Shortly after Orr and his colleagues reported the killings, Ferguson brought a group of scientists and students together to do some brainstorming. Jeff Higdon, a University of Manitoba graduate student at the time, was assigned to look at the database. He found that from 1850 to 2008, whalers and scientists recorded 450 credible sightings, most of which were made in the 1990s and 2000s, when sea ice in the Arctic started to retreat in a significant way.

Higdon and colleague Kristin Westdal, from the marine conservation organization Oceans North, then interviewed more than 100 Inuit hunters from 11 communities. Like Qanatsiaq, almost all reported seeing orcas.

Kyle Lefort, another University of Manitoba grad student who has been working with Ferguson, estimated in a study that there may be as many as 190 killer whales in the Arctic killing 1,000 narwhals annually, approximately the same number that Inuit harvest. Only Canadian Inuit and Greenland hunters can legally hunt narwhal, while both Canadian and Alaskan Natives can take beluga. There are limits on the number of animals each community can harvest.

Ferguson does not believe that orcas are going to have a big impact on the overall population of narwhal, beluga, and bowhead any time soon, at least not in High Arctic waters. But he believes they could adversely affect small, endangered populations of beluga in southern Hudson Bay and in Cumberland Sound, off the coast of Baffin Island. They could also drive beluga, narwhal, and bowhead away from Inuit hunting regions.

It’s not just the Arctic where killer whales are making their presence known. Some orcas are clearly on the move in other parts of the world where they are not often seen, feasting on large marine mammals and shifting the food chain in ways that are catching wildlife managers off guard.

Killer whales occasionally attack great white sharks: When they recently began attacking them off the coast of South Africa near the fishing town of Gansbaai, the great whites fled and have not come back.

In 2019, scientists conducting research off the coast of Australia documented orcas killing and eating endangered blue whales, the largest animal on Earth. John A. Totterdell, lead researcher for the Cetacean Research Centre in Australia, says the discovery is important in determining how whale predation is affecting the recovery of whale species that were overharvested in that part of the world.

This has been the story in Alaska’s Cook Inlet, where orcas may be inhibiting the recovery of the region’s endangered beluga. No one has been able to say for sure because shipping noise, changes in fish distribution, and pollution may also be implicated. What scientists do know is that orca sightings in the region are on the rise.

Killer whales that eat marine mammals are difficult to track with hydrophones, which are submerged under water in strategic locations, because they tend not to communicate while they are on the hunt, quietly homing in on their prey. The chatter comes following a successful kill.

As widespread and beloved by the public as orcas are, very little was known about them until recently. No one knows why one pod began ramming fishing boats in the Mediterranean in 2023 or why some occasionally swim up the Thames River.

Only recently did scientists discover that killer whales that dwell in the deeper waters off the coast of California and Oregon are genetically and culturally distinct from those that are typically found near shore. Unlike near-shore orcas, which prey on salmon and other fish, these orcas are transients that hunt larger mammals, including gray whales and elephant seals, in highly coordinated attacks.

I got a sense of this in 2009 when I was with Jack Orr, of Fisheries and Oceans, while he was capturing and tagging narwhal with a team of Inuit partners from the village of Naujaat, in northern Hudson Bay. In the first week, we saw dozens of narwhals but had no luck catching any in the nets that had been set. The Inuit members of Orr’s team attributed their skittish behavior to orcas, which other Inuit hunters had reported seeing. Laurent Kringayark said narwhal would rather risk swimming into shallow waters where Inuit hunters were waiting than face orcas in the deep.

Like the Inuit hunters Higdon interviewed, the Naujaat hunters had mixed feelings about orcas. On the one hand, they appreciated how the whales aided them in their hunt for narwhal and beluga. But they also feared that they might be killing too many or chasing them away.

Ferguson estimates that killer whale numbers in the Arctic are increasing at a low but steady rate of about 2 percent annually and that killer whales are likely to eventually prey on more vulnerable populations of whales as the ice recedes.

But they do so at their own peril, he says, just as those orcas did when they moved into Foxe Basin in the 1950s and became trapped when the ice closed in. In 2011, a killer whale was found frozen at the north end of Hudson Bay. In 2013, 17 orcas died in southern Hudson Bay when sea ice expanded across the mouth of the bay, sending them to the south. “It was a logical response but essentially a death trap,” Ferguson explained. “They had no idea there was not an exit.”

Scientists do not know how killer whales might affect the recovery of bowhead, whose population was reduced to around 1,500 when commercial whaling ended around 1915 (subsistence hunting was resumed in 1996). But evidence collected by Higdon suggests that they are being targeted more often than previously assumed.

Higdon and his colleagues analyzed photographs of individual bowhead whale flukes from five Arctic regions to estimate the occurrence of rake marks — parallel scars caused by killer whale teeth. Of 598 identified whales, one in 10 bore rake marks from killer whales. A higher occurrence of rake marks was found in Canada’s Repulse Bay and Greenland’s Disko Bay, where adult bowhead dwell seasonally, than in Foxe Basin, where juveniles and females with calves occur. Older bowhead, which have had greater exposure time to killer whales, had higher occurrences of rake marks than juveniles and calves, which may indicate that younger whales do not survive killer whale attacks.

“I wasn’t surprised by the attacks, or pretty much anything killer whales do,” says Robert Pitman of Oregon State University, who coauthored the research paper on killer whales attacking blue whales in western Australia. “They are highly social, intelligent animals that hunt cooperatively, which allows them to take pretty much anything that swims in the sea. Killer whales have always been a threat to blue whales, especially their calves, but blue whales have learned to deal with that.”

He pointed to a recent study published by University of Washington biologist Trevor Branch that suggests that “flight” species — baleen whales, including blue whales, that flee from predators — may have ways of avoiding killer whales, which are considered a “fight” species. According to Branch, male whale singing differs between fight and flight groups, with fight species producing more intricate songs to win group competitions for mates, while flight species produce loud, monotonous songs to attract distant females. Flight species also call at frequencies that are too low for killer whales to detect.

Ferguson and Higdon credit Inuit knowledge for helping to unravel the mystery of how and where killer whales are entering the Arctic, how widespread they are, and whether they are killing bowhead, beluga, and narwhal. “It would have taken us five years or more in the field searching for killer whales to gather the information we got from the Inuit in just a few months,” says Higdon.

The tissue samples sent by the Inuit were also invaluable in determining that these large mammal-eating whales in the Arctic are an ecotype that had not been identified there before. The genetics, says Garroway, indicate that this “new” ecotype in the Arctic is not actually new. Its origins go back to the last ice age.

“The truth is they were likely always there and looking for an opportunity to get back to places they used to hunt before sea ice prevented them from doing so.”