Killer whales that prowl the northeastern Canadian Arctic are the “wolves of the sea” -- and seem to relish their hunts and nutritious, if bloody, kills of seals and whales, according to a new ambitious survey of traditional knowledge by Inuit hunters of Nunavut. 

In often highly sophisticated attacks that appear to be increasing with the retreat of summer sea ice, roving pods of the marine-mammal-eating orcas readily target bowhead whales, seals, narwhals and belugas in the icy waters -- sometimes working together to drown the much larger bowheads or use body wakes to wash seals off ice floes into the sea. 

“When they are stalking prey, killer whales will slow down, move very deliberately, and remain as quiet as possible in order to reduce the wake and sound produced by their dorsal fin moving through the water,” a team of scientists reported in a new study just published in the online journal Aquatic Biosystems. “When they are close to their prey they pick up speed.”

Among the findings:

• The killer whales were sometimes observed to play with their food or eat only choice parts. Ocras will slap narwhals and belugas to break ribs or rip them in half, with one hunter likening their antics to “playing soccer” with hunks of flesh.
• The killer whales were seen working cooperatively to take down the vastly larger bowhead whales, with some orcas sliding up and over the blowhole while others clamp down on flippers.
• These Canadian Arctic killer whales appear to be marine mammal specialists -- similar to certain other killer whale ecotypes found in the North Pacific and other oceans. No hunter reported ever seeing fish consumed.

The insights come from the first study to focus entirely on traditional knowledge of killer whale behavior in the ice-dominated waters off Nunavut in northeastern Canada -- some 105 active marine mammal hunters from 11 Nunavut communities were interviewed between 2007 and 2010.

“Local Inuit have broad knowledge of killer whales as predators, and their observations represent a substantial addition to our knowledge base on this species in the Canadian Arctic, in terms of their distribution, prey selection and hunting behavior,” wrote marine ecologist Steven Ferguson, with the Department of Fisheries and Oceans Freshwater Institute at the University of Manitoba, along with co-authors Jeff Higdon and Kristin Westdal.

“Inuit throughout Nunavut reported that marine mammals are the main prey items, and that all species of the phocid seals and the most commonly occurring cetaceans are consumed,” they added. “Most interviewees reported multiple prey items, and five … referred to killer whales as the “wolves of the sea”, or being “like wolves.”

What do elusive killer whales eat?

The highly intelligent and often rowdy killer whales -- one of Alaska’s iconic marine animals -- may roam all of the world's oceans, from the Arctic to Antarctic, Pacific to Atlantic. But they are notoriously hard to study.