DFO ponders spread of killer whale population in Nunavut

Hungry orcas gorge on Nunavut's marine mammals

By JANE GEORGE

Scientists and Inuit hunters don't always see eye-to-eye on research involving marine mammals.

But both groups are alarmed over the rising numbers of stocky, black and white killer whales that have been turning up in the western Hudson Bay.

Known for their cunning hunting practices and hearty appetites, killer whales appear to have expanded their range to the north and west of Baffin Island, where hunters and scientists fear they will ravage seal, beluga, bowhead and narwhal populations.

Sightings of killer whales used to be rare, but more than 40 killer whales have been spotted in Nunavut waters since 2000. In 2008, there were 10 sightings of killer whales, some as far south as Churchill, Manitoba.

Scientists suspect rising temperatures have paved the way for killer whales to expand their range. That's because they believe decreasing sea ice allows the killer whales to more easily follow, find and kill their prey.

And if global warming continues to reduce ice cover, particularly in western Hudson Bay, killer whales could be poised to become the top predator there, killing off or chasing away other marine mammals, such as seals, narwhals, bowheads and belugas.

"As long as we have ice, they're safe, but the fear is that with global warming and less ice, their range is going to diminish," said Steve Ferguson, a research scientist with the federal Department of Fisheries and Oceans in Winnipeg.

Killer whales were found in the past around Baffin Bay, but not in western Hudson Bay or in the High Arctic islands, although a traditional knowledge study on killer whales says an Igloolik elder predicted a new marine mammal would someday appear in the region.

Now, hungry for the same marine mammals that Inuit hunt, the killers whales have arrived.

A killer whale attack on narwhals at Kakiak Point in Admiralty Inlet saw a dozen killer whales kill several narwhals over a six-hour period in August 2005.

The impact of the killer whales' attack was profound: DFO scientists say the narwhal's movement patterns changed five days before the attack, during the attack, and even five days after the killer whales had left the area.

This has led to concerns that that killer whales are likely to frighten off the marine mammals they don't manage to kill.

Some killer whales appear to eat only fish, but hunters have seen killer whales eating narwhal, beluga, bowhead whale and seal.

And killer whales, which can reach six to eight metres in length (19 to 26 feet) and weigh more than six tonnes, have a huge appetite: a dozen seal tags have been found in the stomach of one killer whale and a caribou in another.

There are thought to be about 500 to 2,000 killer whales summering in the Eastern Arctic region, but no one is sure where killer whales go in the winter.

"They get so much food in the summer so they can coast in the winter. But we don't know where they hang out," Ferguson said.

The DFO hopes analyses of teeth and tagging with satellite markers will offer clues about what the killer whales eat and where they go throughout the year.

While there is general resistance to tagging marine mammals, many Inuit hunters support more studies on killer whales because killer whales may endanger the same species they want to hunt.

Aarluk or killer whale meat is usually given only to dogs. When used in qulliit, its fat is said to burn more brightly than that of other marine mammals.

The DFO first started looking at killer whales in 2005 as part of its "Global Warming and Arctic Marine Mammals" study.

In 2006, Nunavut Wildlife Management Board members rejected funding the DFO killer whale study because it was based on monitoring and photographing whales from scientific vessels, such as the Amundsen, with little Inuit input.

However, with the promise of more hunter participation and input from traditional knowledge, the NWMB supported the study, embarking on a three-year collaboration in 2007.

Hunters are now encouraged to file sighting reports or take photos of killer whales to help the DFO identify them by the size and shape of their back fins, eye patches, and scars.

To date, the DFO has collected 67 killer whale photos and received many completed "killer whale sighting forms." Hunters who report sightings to their hunters and trappers organization or wildlife officer receive a cap, with a killer whale logo, which says "Orcas of the Canadian Arctic" in English and Inuktitut.

The "Aarluk News" newsletter, in English and Inuktitut, also provides updates on the latest research.

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