NOAA On Diverse Fish Diet Of Southern Orcas

Really interesting report from NOAA’s West Coast Fisheries about what fishy meals Southern killer whales eat. While up and down the West Coast, orcas gorge on the annual migrating Chinook salmon before they head into river systems for spawning, they take advantage of a wide variety of dining options throughout the year.

Here’s more from the study, which also covered California’s Central Valley king salmon and their impact from the eating whales:

Endangered Southern Resident killer whales prey on a diversity of Chinook and other salmon. The stocks come from an enormous geographic range as far north as Alaska and as far south as California’s Central Valley, a new analysis shows. …

…”When so many prey species are endangered, then they lose some of that diversity,” Hanson said. “The question for managers is how do you support and improve this diverse portfolio of species and stocks.”

The analysis also revealed that the whales prey almost exclusively on Chinook salmon when they are available in the summer. However, they diversify their diet the rest of the year to include species such as skates, halibut, and lingcod, as well as steelhead, chum, and coho salmon. Most of the salmon the whales consume in winter and spring come from three large river systems: the Columbia, Sacramento, and rivers entering Puget Sound.

The researchers examined more than 150 prey and fecal samples collected from the whales from 2004 to 2017. This produced the most comprehensive picture yet of Southern Resident prey over the course of the year.