Killer whales eating their way farther into Manitoba

The food chain in Hudson Bay is drastically changing as killer whales take advantage of less sea ice and eat their way into Manitoba, a researcher in Arctic mammal populations says.

Killer whales could replace polar bears as the top predator in Hudson Bay, researcher says

Killer whales used to be uncommon occurrence in Churchill, Man. A pod was seen moving through the Southern Hudson Bay in 2014. (Brian Fergusson)

The food chain in Hudson Bay is drastically changing as killer whales take advantage of less sea ice and eat their way into Manitoba, a researcher in Arctic mammal populations says.

Steven Ferguson, a researcher with Fisheries and Oceans Canada and the University of Manitoba, will be presenting his findings in Winnipeg this week at ArcticNet 2016, the largest single gathering of scientists focused on the rapidly changing Arctic.

"We are seeing a lot more killer whale activity in Hudson Bay and they are a top predator. They are really a magnificent, interesting predator — highly efficient," Ferguson said.

With the changing sea ice in Hudson Bay, killer whales could replace polar bears as the top predator, a researcher says. (Martin Harvey/WWF)
Killer whales are not a fan of sea ice because it bothers their dorsal fins. However, sea ice is melting earlier and forming later each year.

Ferguson said that means killer whales are spending more time farther into Hudson Bay and "they are there to eat."

"They appear to be eating other whales and seals and, I would imagine, if we lose our sea ice they will replace polar bears as that top predator," he said.

While the killer whales may finally be free to swim the bay for longer periods of time, Ferguson said it can have major consequences for other species.

Thousands of belugas migrate each summer from the Hudson Strait in the east to the warmer waters of river estuaries on the western side of the bay to feed, mate and rear their young. It's estimated that the western Hudson Bay beluga population totals 57,000, making up about 35 per cent of the world's total.

"They are prey for killer whales," Ferguson said.

"They are food for killer whales and we've had a few instances where we have recorded attacks by killer whales on the beluga population. It probably happens more often than we know because it's not an easy thing to observe."

More killer whale activity in the bay could mean major trouble for belugas, he added.

Thousands of beluga whales come to the mouth of the Churchill River each summer and spend much of their time feeding on small fish called capelin. (Courtesy explore.org)
Killer whales aren't the only predator taking advantage of the melting sea ice. Greenland sharks are also making their way into some parts of Hudson Bay, but since it's shallow, they don't go in as far.

ArcticNet 2016 will see 800 scientists from across the country gather at the RBC Convention Centre to present research on a wide array of subjects impacting the health of the biology and the physical systems of the Arctic. The Arctic is changing incredibly quickly, largely driven by the changes in the ice cover.

Ferguson said the predictions for an ice-free summer are becoming earlier — it will probably happen in the next 10 to 15 years.

"That still means we have ice in the winter, and we could have quite a bit of ice, which is important for the arctic ice adapted species like the beluga whale," he said. "But it's hard to know how far the melting will go and whether [we will] have sea ice at all in 100 years."

The ArcticNet meeting takes place from Monday to Friday. For more information visit their website.