Why you should care
A rapidly changing Arctic Ocean means some traditional species are imperiled while new arrivals thrive.
Change creates winners and losers, and that includes climate change, especially at the top of the world. On the losing side of the environmental ledger we find the polar bear, floating glumly on its ever-shrinking ice floe. On the winning side, a new apex predator is cruising northern waters.
In an increasingly ice-free Arctic Ocean, killer whales are being sighted for the first time off northern Canada and Alaska’s North Slope.
Since 1984, the Arctic Ocean’s multiyear ice pack has shrunk from 61 percent coverage to 34 percent, according to a National Snow & Ice Data Center report. Bad for bears roaming a frozen realm to hunt ringed seals and other prey; good for killer whales, or orcas, which in years past have avoided the region because their 6-foot-high dorsal fins make it difficult for them to zoom around under the ice in pursuit of fish, sharks and other prey.
But these carnivorous members of the dolphin family, which are up to 32 feet long and tend to prowl in packs of about 10, now are exploiting a new hunting ground way up north, particularly in the eastern Canadian Arctic, around Baffin Island and Hudson Bay, notes Donna Hauser, research assistant professor at the University of Alaska Fairbanks.
And there’s more bad news for bears. Orca prey includes ringed seals — a favorite food of a polar bear population already stressed by vanishing ice. Also on the menu are such whale species as narwhal, beluga and bowhead. “The open water is an advantage for the killer whales as they have a longer window of time to hunt,” says Steve Ferguson, research scientist at Fisheries and Oceans Canada.
The orcas are already making their presence felt. A 2017 report published in the journal Proceedings of the National Academy of Sciences of the United States of America concludes that “the presence of killer whales significantly changes the behavior and distribution of narwhal.”
A factor related to shrinking ice is also disrupting the region. The volume of warmer Pacific water flowing into the Arctic Ocean via the Bering Strait has surged 70 percent over the past decade and now equals 50 times the annual flow of the Mississippi River, according to a paper published this year in the journal Progress in Oceanography. An increasing northerly flow is also occurring on the Atlantic side of the basin.
When the orcas are winning, the rest of us may be losing.
That’s helped other opportunistic species wend their way north. Humpback whales, marine mammals typically found in the sub-Arctic, have been sighted off Alaska’s North Slope for the first time. To the east, mackerel, cod and other fish native to northern European coasts are migrating deeper into the Arctic Basin, toward Siberia. Newly invasive bird species like the crested and least auklet, northern fulmar and short-tailed shearwater are pushing aside black-legged kittiwakes, thick-billed murres, glaucous gulls and other traditional summer residents of the northland.
Given that sea ice helps cool the planet by reflecting sunlight back into space, its loss almost surely will alter climate and weather beyond the Arctic. As yet, scientists aren’t quite sure how. But there’s a chance that when the orcas are winning, the rest of us may be losing.