February 19, 2021 — Snake River spring-summer chinook could be nearly extinct by 2060 and interventions are “desperately needed” to boost survival in every stage of their lives, scientists warn.
The findings, published Thursday in the journal Communications Biology, modeled survival of eight populations of wild Snake River Basin spring-summer chinook during the ocean phase of their life, under various climate-warming scenarios.
Salmon hatch in rivers, but mature for years at sea before they return to the waters of their birth. It is a perilous life cycle that could become all but impossible for some already fragile salmon populations that make one of the most arduous of all journeys, all the way to Idaho. They travel more than 1,800 miles round trip, climb more than a mile in elevation, and tackle eight dams, each way: four on the main stem Columbia, then four more on the Lower Snake River.
Add just a little ocean warming, and it’s curtains. Populations declined in all eight basin chinook populations for which the scientists ran predictions. Just a little more than 1 degree Celsius temperature increase in sea-surface temperature produced dire effects — with mortality as high as 90% in warmer seas.