Biotechnology

Tastes are different – ​​even among North Atlantic killer whales


Killer whales (also known as orcas) are intelligent predators. While it is known that killer whales in the Pacific Northwest exploit a wide variety of foods, even within the same area, we know much less about the feeding habits found throughout the North Atlantic. Thanks to a new technique developed by a research team led by McGill University, it is now possible to measure, for the first time, the proportions of various prey that killer whales eat in the North Atlantic by studying the patterns of fatty acids in their blubber. .

Killer whales (also known as orcas) are intelligent predators. While it is known that killer whales in the Pacific Northwest exploit a wide variety of foods, even within the same area, we know much less about the feeding habits found throughout the North Atlantic. Thanks to a new technique developed by a research team led by McGill University, it is now possible to measure, for the first time, the proportions of various prey that killer whales eat in the North Atlantic by studying the patterns of fatty acids in their blubber. .

In the largest study of its kind, this approach was used to take a closer look at the diets of killer whales from the eastern and northern coasts of Canada all the way to northern Norway. It provides the most detailed description of the diet of North Atlantic killer whales to date. As climate change leads to a redistribution of killer whales northward, the results have implications not only for the health and survival of these killer whales, but also in terms of the potential impact on sensitive species in Arctic ecosystems.

New tool for tracking dietary changes

“In the context of climate change, it becomes even more urgent to understand and be able to measure the diet of killer whales and how they are changing so that we can estimate the potential impacts on local food webs,” said Anaïs Remili, PhD candidate in the Department of Natural Resource Sciences at McGill University and author of first in a paper published in Journal of Animal Ecology. “By measuring the fatty acid composition of about 200 killer whales and 900 different species of prey, we were able to estimate the specific proportions of each prey species in the whale diet. This means that scientists can potentially track any changes in this diet in the future.”

Orcas’ food habits vary – by region and by individual

The team found that killer whales have very different diets across the North Atlantic. In some areas, killer whales prefer to eat other whales: beluga whales and narwhals in the Eastern Canadian Arctic and baleen whales and dolphins in Eastern Canada.

Killer whales mainly feed on fish, especially herring in the Eastern North Atlantic (Norway, Faroe Islands, Iceland), and in the Central North Atlantic (Greenland) they mainly eat seals.

Interestingly, however, the McGill researchers also found that not all whales in a given location ate the same prey. For example, in the Eastern Canadian Arctic, half of the whales eat mainly beluga and narwhals, while the other half eat ringed seals. In Greenland, killer whales consume a mix of all available prey. Finally, in Iceland, the Faroe Islands and Norway, most whales are herring eaters, but small numbers of whales in Norway and Iceland also eat mostly marine mammals such as porpoises and seals. This is the first time researchers have been able to detect individual dietary preferences with this level of detail.

“Measuring the diets of killer whales and other top predators is especially important in the context of changing environments, as it can provide insight into how these animals adapt to changing prey populations and habitat conditions,” added Melissa McKinney, senior author on the paper, Assistant Professor in the Department of Resource Sciences. Nature at McGill and Canadian Research Chair in Ecological Change and Environmental Stressors. “Our results also point to the need for further research into individual ecology as we found large differences among individuals from the same population.”

Learning:

“Quantitative fatty acid signature analysis reveals a high degree of food specialization in killer whales in the North Atlantic by Anaïs Remili et al. in the Journal of Animal Ecology. DOI: https://doi.org/10.1111/1365-2656.13920




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