07/29/2026
Species Feature July:
Chinook Salmon (Oncorhynchus tshawytscha)
"I started my career assessing Chinook Salmon populations many moons ago, and since then have loved all things salmon, so be forewarned this may be a multipart series, since I could go on about how awesome salmon are indefinitely. But I need to go over some salmon basics first! You may (or may not know) that right in your back yard, here in the Sacramento River, is the largest run of Chinook Salmon in the state. Chinook Salmon, or King Salmon, are the largest Pacific Salmonid species (that is why they are the king!)...
..The Sacramento River supports four distinct runs of Chinook Salmon: Fall, Late-Fall, Spring, and Winter, all of which are technically Chinook Salmon (Oncorhynchus tshawytscha), but their separate life histories are what makes them different..." (Part 1)
"You may think that all these runs are created equal, but this is not the case. Winter-run is one of our most important runs, in that it is the most endangered out of the four runs. It was officially listed as endangered back in 1989, and even had an all-time low of only 186 spawners returning to the Sacramento River in 1993.
You may be asking why this run of salmon is struggling so much… The short answer is Keswick and Shasta dams, but the long answer is a little more complicated. Looking back to their life history, we know that winter-run spawn all the way until July, leaving their nests to incubate for three months after in the hottest months of the year. Salmon eggs need water temperatures to be between 42.5 and 57.5 degrees Fahrenheit to incubate. This made sense as a life strategy when these salmon were able to access the cold waters of the upper Sacramento River, but now they are cut off from those waters..." (Part 2) - Stacey Alexander
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(pc: USFW, Jane Work, RCD of Tehama County)