Killer Whale Diets: Tracking Adaptation and Pollution Risks
We study what Norwegian killer whales eat and how their diets change over time to understand how it affects their health and ability to cope with a changing ocean.
Norwegian killer whales feed on a variety of prey, from fish to marine mammals, and their diet shapes both contaminant exposure and their ability to adapt to changing habitats. This long-term, continuous project aims to uncover patterns of dietary habits and how they vary between individuals and groups over time.
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We combine visual observations of predation events collected by drones with molecular analysis of prey remains found at the surface to identify target species. Dietary markers such as fatty acids and stable isotopes from biopsy samples allow us to evaluate long-term feeding habits, while multi-sensor camera tags attached with suction cups quantify activity budgets and prey profitability.
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So far, our research confirms that herring, mackerel, lumpfish, salmon, seals, and porpoises are part of Norwegian killer whales’ diet. Some groups are herring specialists, while others switch seasonally or opportunistically to different prey. A subset of whales that feed on marine mammals as well as fish carry four times higher contaminant levels than those eating only fish, though there is currently no evidence of exclusively mammal-eating whales in Norway.
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By identifying feeding behaviors and food sources, this project provides crucial insights into the sources of contaminants and the resilience of Norwegian killer whales to increasingly disturbed marine ecosystems.