Killer¹ whales (Orcinus orca) are the top marine² predator³, wherever they are found, and seem to eat everything from schools of small fish to large baleen⁴ whales（须鲸） , over twice their own size. 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 ecosystem⁵ balance. New research published in BioMed Central's re-launched open access journal Aquatic⁶ Biosystems has combined scientific observations with Canadian Inuit traditional knowledge to determine killer whale behaviour and diet in the Arctic. Orca have been studied extensively in the northeast Pacific ocean, where resident killer whales eat fish, but migrating whales eat marine mammals. Five separate ecotypes（生态型） 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 prey⁷ preference or behaviour.

Traditional Ecological⁸ Knowledge (TEK) is increasingly being used to supplement scientific observations. Researchers from Manitoba visited 11 Canadian Nunavut Inuit communities and collated⁹ 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, harp¹⁰, 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 varied¹¹ between areas. Most incidents of killer whales eating bowhead whales occurred in Foxe Basin and narwhal（独角鲸） 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 ramming¹² 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 behaviour 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 tusks¹³ (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 seasonal¹⁴ visitors to the area and have recently started colonising Hudson Bay (possibly due to loss of summer sea ice with global warming). Local communities are reliant（依赖的） on the very species that the orcas like to eat. Dr Steven Ferguson from the University of Manitoba who led this research commented, "Utilising local knowledge through TEK 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."