This blog post on the Ecological Society of America website sums up a study published recently regarding the prey of southern Alaska resident killer whales, a group that, like the SRKW, enjoys a diet of fish.

The study does recognize the standard take on diet for the SRKW.

Southern residents, in particular, feed almost exclusively on Chinook salmon (Oncorhynchus tshawytscha) in spring and summer—though their diet is significantly more diverse in fall and winter (Hanson et al., 2021).

But introducing DNA analysis in addition to the standard fecal analysis showed some interesting results.

In the case of resident killer whales, extensive data collected from the southern resident killer whale population during summer months have been relied upon to describe the diet of resident killer whales generally (Adams et al., 2016; Chasco et al., 2017; Ohlberger et al., 2019). However, recent studies, including this one, indicate a greater degree of spatiotemporal, population-level, and socially driven variability in diet than had previously been observed (Ford et al., 2016; Filatova et al., 2023; Van Cise et al., 2024).

The ESA blog post summarizes the cogent points nicely:

“Switching between these salmon species — with important contributions from groundfish — is a different narrative from the one we usually hear about the diet of fish-eating killer whales in the North Pacific, which emphasizes Chinook salmon as their primary prey,” said Myers, the lead author of the paper.

One might well wonder if the SRKW are pursuing other than chinook salmon when those non-chinook species are in abundance.