A team of Canadian researchers have melded scientific method with traditional Inuit knowledge, to give us our first glance at what killer whales are dining on and how they’re doing it, in Canada’s North.
Killer whales kill – shocker, eh – but the world’s top marine predator is known to have a diet that’s as varied as their hunting technique and location in the world’s oceans.
Now, a team of Canadian researchers are melding scientific methods with traditional Inuit knowledge, to give us our first glance at what they’re dining on and how they’re doing it in Canada’s North.
“They’re marine mammal eaters and they’re all ice-adapted marine mammals,” Steven Ferguson, study co-author and marine biologist from the Department of Fisheries and Oceans’ Fresh Water Institute and the University of Manitoba told Science-Fare.com. “The Killer whales that look to them for a meal have to adapt too and they’re using different hunting skills that haven’t really been reported elsewhere.”
The Inuit – who call the killer whales the ‘wolves of the sea’ – described first-hand, how they hunted, often co-operating with other killer whales to kill much larger baleen ones, like bowheads. They also use non-traditional tactics like holding the bowhead’s flippers or tail, or even covering the blowhole while another killer whale beats it, causing internal damage.
The Inuit also said carcasses that wash up on shore show signs of selective eating when they consumed their prey.
“Killer whales are trying to eat as much as they can and get the best choice parts,” Ferguson, who’s also a scientist with Fisheries and Oceans Canada, said. “Typically in high latitudes you need lots of fat, so they’re probably keying in on the fatty food.”
“Inuit do the same thing when they eat the whales they harvest, they usually eat the maqtaq – the skin and fat on the outside – not the meat itself,” he added.
Seals though, were identified by the Inuit as the whale’s most common food source. In addition to batting them in the air with their tails, researchers say the killer whales will stir up the water in order to try and knock them off smaller ice floes.
The Canadian team visited 11 communities in Canada’s North and interviewed more than a hundred Inuit hunters and Elders.
For thousands of years the Inuit have had a frontline view of the ocean’s activity and researchers say this can provide valuable insight – especially in an area that’s not easily accessible.
“As hunters they spend a lot of time out on the water observing things and it’s for their livelihood,” Ferguson said. “Their observations are really key – and tied to their lifestyle – and their memory of these events is probably different.”
Recalling events so well may be related to their oral history Ferguson says. Because their livelihood is tied to the oceans, their accounts are as important as the whaling books the researchers also used to learn about the killer whales.
“It was like a goldmine of resources when we interviewed them, Ferguson said. “We were really surprised at the detailed knowledge they had about killer whales and their feeding habits.”
Whaling logbooks from the 1800’s report killer whales habiting the Davis Strait and Baffin Bay during the summer months when ice’s at a minimum. With the ice levels decreasing, what was once a seasonal visitor may now be moving in and leaving seasonally.
For the first time ever, they’ve even been sighted in Hudson Bay – where they’re directly competing with the North’s other top predator, the polar bear.
“Certainly their activity’s increasing,” Ferguson said. “This is kind of a bad news story in the sense that we’re losing sea ice and we may end up losing the whales, seals and polar bears that need the ice”
They need it for a variety of reasons. In one hand, researchers say, whales, like narwhals, belugas and bowheads have all adapted to use the ice as protection from killer whales. They’ve even lost their dorsal fin which makes it easier for them to navigate below the ice, and away from the killer whales that haven’t lost theirs.
In the other hand, seals and polar bears use it as a base to hunt from and as the ice’s lost, they’re being forced to learn how to hunt from land – opening up vast amounts of ocean for the killer whales and other marine species to thrive in.
“Instead we’re going to start seeing their predators, like killer whales, moving into the area and changing the whole eco-system,” Ferguson said. “The eco-system could get more diverse – it could have a lot more new species – but the sad part is we may be losing those that are really adapted to the ice itself.”
Although largely untapped by science, one region has been studied. Where the two studies overlap, the researchers are finding congruency – both identify narwhal whales as habitants and menu choices for Orcas in the area.
“This could give us an idea of what areas we should be watching and making sure we don’t see signs of the narwhal population being reduced by killer whale predation,” Ferguson said. “We don’t have any evidence of that yet, but it’s a cause for us to watch and monitor these areas.”
This doesn’t just lend more strength to the notion of engaging the Inuit people in order to study these harsh environments; it allows researchers to use other sites to help monitor the killer whales and the overall health of this increasingly hospitable ecosystem.
The findings were published in the premier issue of the online journal, Aquatic Biosystems.