Southeast Alaskan orcas have proven to be not just 'salmon' predators, but flexible opportunists that change their diet according to the season and habitat.
A long-term study (1991–2021) analyzing prey remains and DNA from feces showed that in the Kenai Fjords in May–June, 77% of the orcas' diet consists of king salmon, in the eastern part of Prince William Sound in June–July, 62% is comprised of sockeye salmon, and in the western part of the bay in July–September, 77% is made up of coho salmon.
Orcas literally follow salmon as it matures. However, their diet is not limited to salmon: halibut, arrowtooth flounder, and coal fish were regularly found in samples (up to 5% of samples). One family group (AE) actually specialized in flatfish.
Different pods prefer different areas and fish species, but some, like the AK2 group, roam throughout the region, switching between king salmon and sockeye salmon and back. This flexibility likely explains why the population of about 1,000 individuals remains one of the largest in the northern Pacific Ocean.
For fisheries management, this data is crucial. While it was previously thought that orcas relied almost exclusively on king salmon, many populations of which are threatened, it is now clear that they are capable of switching to other species. This means that conservation measures must take into account the entire seasonal spectrum of their prey base.
