The researchers found that the personality traits of killer whales are similar to those of humans, but are more similar to those of chimpanzees. (iStock) A team of researchers from McGill University has developed a promising technique that reveals the diet of killer whales across the North Atlantic.
The study, published in the Journal of Animal Ecology, reveals the method to recreate the exact diet of these whales using only a sample of their skin and blubber.
Anaïs Remili, a PhD student at McGill University who took part in the study, explains that scientists are studying the diets of the ocean’s largest predators, which change depending on the environment. “In fact, the amount and type of food they eat can affect the functioning of ecosystems. »
Ms Remili says researchers know killer whales are one of the largest predators in the oceans, but that knowledge of their diet, including the amount of each species they consume, is incomplete.
“Orcas are intelligent predators that are known to employ specific hunting techniques,” she points out. This allows them to hunt almost all species, from fish to fur seals to blue whales, in all oceans. »
The study shows that different groups of killer whales have evolved distinct “ecotypes” based on location and evolution, meaning unique diets and lifestyles.
“These ecotypes have been studied extensively for decades because killer whales live in densely populated areas, allowing scientists to observe these individuals year-round. »
Our technique measures the lipid composition of whale blubber and uses a computer program to recreate the most likely proportion of each prey species in an individual’s diet.Anaïs Remili, PhD student at McGill University
The cold waters of Norway’s far north are welcoming more and more orcas in search of food. (Radio Canada)
Comparing different groups of killer whales around the world shows that there’s still a lot we don’t know about them, says Remili in a scientific paper published on The Conversation. Note that killer whales are gradually moving toward the Arctic due to climate change.
“It is difficult to determine what eats killer whales that live in remote areas of the Arctic such as Baffin Bay, Greenland and the Norwegian Arctic. Spotting food can be difficult in the choppy waters of the Arctic Ocean. »
The PhD student adds that early studies indicated that there were two species of killer whales in the North Atlantic: those that feed on marine mammals and the other group that feeds on fish and sometimes seals. “However, the lack of data, combined with new evidence, has led scientists to propose that this classification be withdrawn. It appears that some North Atlantic populations have a more diverse diet. »
Because of the difficulties in collecting observational data, the researchers focused on the chemical signals they can measure in the skin and blubber of killer whales in the North Atlantic. “These chemical signals can be lipids or stable isotopes that tell us what killer whales eat and how they affect the food chain. »
Thanks to this technique, scientists can now estimate the exact percentage of different species in each whale’s diet, says Ms Remili. “But what surprised us the most was the degree of variation between diets within each population. »
In the western North Atlantic, individuals are concentrated on either cetaceans – marine mammals such as belugas and narwhals – or seals. In the central North Atlantic, killer whales will feed on any available prey.
“And killer whales in the eastern North Atlantic seem to mostly stick to a fish-rich diet,” says the PhD student, adding that several killer whales from Norway and Iceland complement the fish with marine mammals.
“We now know that individuals in the same population can have different diets,” she concludes.
With information from Anaïs Remili