Global warming: How will Arctic ecosystems change?

What do orcas really eat? PHOTO COURTESY NOAA.

Scientists supplement research with traditional indigenous knowledge

By Summit Voice

SUMMIT COUNTY — As Arctic sea ice melts at unrelenting pace, marine biologists are trying to understand how ecosystems in the North Pole region may change. As with any ecosystem, apex predators are critical. In the Arctic Ocean, killer whales fill that role, eating nearly everything, from schools of small fish to large whales.

The increase in hunting territories available to killer whales in the Arctic due to climate change and melting sea ice could seriously affect the marine ecosystem balance. Some new research, recently published in BioMed Central’s re-launched open access journal Aquatic Biosystems, has combined scientific observations with Canadian Inuit traditional knowledge to start answering some of those questions by determing killer whale behaviour and diet in the Arctic.

Research in the northeast Pacific ocean has shown that resident killer whales eat fish, but migrating orcas eat marine mammals. In Antarctic waters, five separate ecotypes in the Antarctic have been identified. Each preferring a different type of food, and similar patterns have been found in the Atlantic, tropical Pacific, and Indian oceans.

However, little is known about Arctic killer whale prey preference or behavior. To gain a better understanding, scientists are taking advantage of traditional ecological knowledge, passed down among generations of indigenous people. Researchers from Manitoba visited 11 Canadian Nunavut Inuit communities and collated information from over 100 interviews with hunters and elders.

The Inuit reported that killer whales would ‘eat whatever they can catch’, mainly other marine mammals including seals (ringed, harp, bearded, and hooded) and whales (narwhal, beluga and bowhead). However there was no indication that Arctic killer whales ate fish. Only seven of the interviewees suggested that killer whales ate fish, but none of them had ever seen it themselves.

The type of reported prey varied between areas. Most incidences of killer whales eating bowhead whales occurred in Foxe Basin, while narwhal predation was more frequent around Baffin Island.

Inuit were also able to describe first-hand how killer whales hunted, including several reports of how killer whales co-operated to kill the much larger bowhead. During the hunt some whales were seen holding the bowhead’s flippers or tail, others covering its blowhole, and others biting or ramming to cause internal damage. Occasionally dead bowheads, with bite marks and internal injuries but with very little eaten, are found by locals.

‘Aarlirijuk’, the fear of killer whales, influenced prey behavior with smaller mammals seeking refuge in shallow waters or on shore and larger prey running away, diving deep, or attempting to hide among the ice. Even narwhal, which are capable of stabbing a killer whale with their tusks (although this is likely to result in the deaths of both animals), will run to shallow waters and wait until the whales give up.

Killer whales are seasonal visitors to the area and have recently started colonizing Hudson Bay (possibly due to loss of summer sea ice with global warming). Local communities are reliant on the very species that the orcas like to eat.

“Utilising local knowledge through (traditional ecological knowledge) will help scientists understand the effects of global warming and loss of sea ice on Arctic species and improve collaborative conservation efforts in conjunction with local communities,” said Dr. Steven Ferguson from the University of Manitoba, who led this research.

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5 thoughts on “Global warming: How will Arctic ecosystems change?

  1. More knowledge on this subject. And with it, comes more efficient methods of gathering that knowledge. It seems that the Phoenix syndrome is playing out here, in ways that we might not have expected.

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