Monday May 12, 2025
The Cool Down —
New research by the University of Western Australia shows that California’s wild salmon population is at risk because of climate-driven environmental shifts, and scientists warn the impact could be permanent if extreme drought conditions continue.
The study, led by the University of California and published in Proceedings of the National Academy of Sciences, found that the state’s salmon are losing access to their traditional spawning streams as water flow decreases because of climate shifts.
Salmon typically migrate from the ocean back to the rivers where they were born to spawn. But during California’s record-breaking drought from 2011 to 2014 — described as a “one-in-a-thousand-year” event by study co-author and associate professor Sally Thompson — many rivers didn’t begin flowing until months later than normal.
Streams that usually swelled in November stayed dry until January, cutting off the upper reaches and leaving salmon stranded downstream. As a result, breeding failed across several species in rivers throughout Northern California.