VMP that is fascinating, thanks for the linkI have also encountered schools of anchovies and in salmon stomachs in Central Puget Sound this Summer. While other Puget Sound forage fish such as most Pacific herring stocks have been declining, Pacific anchovies are going from usually episodic around warmer water conditions (such as around the 2015 strong El Nino, seems this in this El Nino too) to increasingly common in our waters. Athough there are no good historical baselines for anchovies in Puget sound, warmer waters under climate change favors them over other forage fish.
Unfortunately it is not a fair like for like diet swap for salmon and other fish since anchovy dominated diets have been recently found to be behind thiamine (B1 vitamin) deficiency complex (TDC). Anchovies have an enzime called thiaminase, which as the name indicates, breaks down thiamine. As salmon eat on anchovies, the thiaminase destroys their own vitamin B1 supply. TDC results in neurological and behavioral changes in fish, swimming in circles, disorientation, etc resulting in lower survival. The impact is compounded since offspring of B1 deficient salmon have shown 40% to 90% mortality in heavily affected populations, such as California's Central Valley Chinook salmon.
So although cool to see them around, and while they may provide fishing opportunities in the short term, it may not translate into monster well fed fish or better fishing opportunities in the mid to long term.
See below links for more information on this.
Anchovy found on an Elliot Bay king salmon this Summer
View attachment 195601
Anchovy Dominated Diets off the West Coast Pose New Dangers for Salmon
Lack of key vitamin turns fatal for as many as half of salmon offspring.www.fisheries.noaa.gov
In humans with dietary deficiency of Thiamine perhaps the weirdest aspect of it is the confabulation. They lose the ability to make short term memory and yet make up all kinds of nonsense. Big time alcoholics who get all their nutrition through booze are high risk for this. Years ago, maybe still to this day, in Harborview's ER the hard core alcoholics pretty much get a shot of thiamine, maybe a phenobarb chaser to prevent DTs regardless of why they are there...
.