Salmon on the ropes

Warming streams could kill off spring-run chinook salmon in California before the end of the century.

Almost all projected scenarios using a model of the Butte Creek watershed ended in the demise of the fish, as water in the stream became too warm for them to survive the summer and spawn in the fall, according to a study by UC Davis, the Stockholm Environment Institute and the National Center for Atmospheric Research.

The only option that preserved the salmon population for at least a few decades involved reducing diversions for hydropower during heat waves.

“If we leave the water in the stream at key times of the year, the stream stays cooler and fish can make it through the fall,” said Lisa Thompson, director of the Center for Aquatic Biology and Aquaculture at UC Davis.

The salmon population already faces threats from pollution, as well as introduced predators and competitors.