Killer Whales and Their Prey in Iceland

Scientists have very little information about the population or feeding patterns of killer whales (Orcinus orca) in Iceland. These animals play an important role in ecosystems – as top predators, they can affect the size of populations of prey species, which in turn affects the rest of the food chain. These interactions are known as trophic cascades and have the potential to reshape the environment.

Killer whale populations can vary considerably in terms of their feeding strategies, and they adapt these behaviors based on which prey are available. Some populations, for example, feed primarily on herring, while others feed on multiple species, including marine mammals such as whales and dolphins. Prey selection influences killer whale behavior, such as the way they form social groups, interactions between different animals, and their communication systems. Furthermore, prey selection can introduce other threats. For example, killer whales that feed on marine mammals or cod – species that are higher up on the food chain – are likely to consume higher levels of pollutants, which can affect their reproductive rates and the survival of their calves.

This is the first study in Iceland to assess the diet of killer whale populations in an effort to understand potential threats to the species. Data will be collected through observations of the type of prey different whales are feeding on, as well as through the collection of small samples of skin and blubber. These data enable scientists to quantify the level of pollutants in killer whales’ bodies, understand their diets, and record their genetic material.