To reconstruct the whales’ diets, the researchers used a model called Quantitative Fatty Acid Signature Analysis (QFASA) using samples from captive killer whales. They then measured the fatty acid composition of the wild Greenland killer whales and potential prey species the whales may feed on. Finally, they applied the modeling approach to estimate that the whales mainly feed on harp and hooded seals, species that researchers found in some of the whales’ stomachs.

This new tool has the potential to improve understanding of diets of killer whales around the world, and how killer whales might impact Arctic food webs in the future.

Validation of quantitative fatty acid signature analysis for estimating the diet composition 2 of free-ranging killer whales by Anaïs Remili et al., was published in Nature.