Killer whales are moving further north as the Arctic ice cover melts, raising concerns that they may imperil traditional Inuit fisheries.

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MONTREAL: Killer whales are migrating further north as the Arctic Ocean's ice cover melts due to global warming, according to Canadian researchers.

"We found a really direct correlation with decreasing ice in the Arctic and more observations of killer whales so we think they are moving further into the Arctic because of less ice," said Steven Ferguson, a scientist involved in the study, at the arctic division of the Canadian fishing ministry.

The arrival of the massive predators in the far north could threaten the livelihood of the native Inuit who traditionally depend on fishing for their food.

Ferguson's team last year was notified of sightings of the black and white orca (Orcinus orca), by scientists, tour operators and Inuit fishermen who criss-cross Hudson Bay - a northern Canadian inland sea bigger than France.

In the 1980s, experts counted between five and 10 summer sightings of orca each year in the same area. That number jumped to about 30 last year, the Canadian researchers said. During the same period, the ice cover in the Arctic has sharply declined.

And according to a study recently published in the journal Geophysical Research Letters, by 2040 the ice could be completely gone during the summer (see Arctic ice cap to disappear by 2040, Cosmos Online).

Ferguson's team was unable to identify where the orca seen in Hudson Bay were coming from, but said they were probably from the northern Atlantic Ocean, near Iceland or Nova Scotia. The researchers were also unsure what was on the menu for the giant creatures, which are not true whales, but are the largest members of the dolphin family.

"We don't know for sure what the killer whales are eating. Some killer whales eat fish but we don't think there is that much good fish food for them in the Arctic. So we are working on the assumption that they are probably eating belugas, narwhals, bowhead and maybe seals as well," Ferguson said.

Their migration is worrying fishermen of the Inuit, the indigenous Eskimo people of the region, he said in discussions of the research led in cooperation with the University of Manitoba. "It's a real concern for the hunters. They think it is competition for their food because the [narwhals, belugas, and other creatures] that they would be shooting and eating would be attacked by the killer whales," he said.