Chinook Salmon Are Swimming in This California River for the First Time in More Than 80 Years
The juvenile fish recently hatched from eggs that scientists deposited in the gravelly riverbed of the North Yuba River last fall
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Chinook salmon were once abundant in the North Yuba River in California’s Sierra Nevada. But since 1941, they’ve been kept out of the chilly, clear waters by the Englebright Dam.
Now, for the first time in more than eight decades, the iridescent, blue-green fish are once again swimming in the northern waterway, the California Department of Fish and Wildlife announced in a statement this month.
The young spring-run Chinook salmon are part of a pilot project that may one day become a full reintroduction program, with the eventual goal of returning the fish to their historic spawning grounds in California’s mountains. The project is a collaboration between the California Department of Fish and Wildlife, the Yuba Water Agency, National Oceanic and Atmospheric Administration (NOAA) Fisheries and the U.S. Forest Service.
The juveniles gliding through the North Yuba today recently hatched from eggs that were deposited by scientists last fall.
In October, researchers visited a 12-mile stretch of the North Yuba near the town of Downieville, roughly 100 miles northeast of Sacramento. Working along that stretch, they used a hydraulic injection system to build dozens of man-made salmon nests, called redds, in the gravelly riverbed. After clearing the nests of silt, they injected 300,000 spring-run Chinook salmon eggs up to 1.5 feet deep—an action designed to mimic the spawning behaviors of real adult salmon.
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They hoped the eggs would eventually hatch and that baby salmon would emerge and start swimming around. That dream became a reality four months later when, on February 11, scientists found young salmon in a trap several miles downstream from the egg deposit sites.
Now, biologists are gathering the baby fish, loading them onto trucks and driving them downstream. They’re trucking the salmon past the Englebright Dam and releasing them into the lower Yuba River, so they may continue swimming toward the Pacific Ocean.
In recent years, crews have deconstructed several dams near the West Coast, including four on the Klamath River in California and Oregon as part of the largest dam removal project in U.S. history. However, the Englebright Dam will likely stay put. (Another dam on the Yuba River, the New Bullards Bar Dam, is also blocking the fish’s way.) So, for the foreseeable future, that means scientists will need to keep trucking the juvenile fish downstream.
“It seems like a lot of effort for sure, it seems crazy,” Flora Cordoleani, a scientist at the National Oceanic and Atmospheric Administration’s Southwest Fisheries Science Center, told the San Francisco Chronicle’s Julie Johnson last year. “But it’s for the whole ecosystem.”
Chinook salmon are an “emblematic species,” similar to the bald eagle, Cordoleani added. “A healthy salmon population means a healthy ecosystem.”
Reintroducing spring-run Chinook salmon to the North Yuba River is important for the species’ survival. The spring-run Chinook that live in California’s Central Valley are listed as threatened by both the state and the federal government. And the cold waters of the North Yuba River are considered the region’s most climate-resilient habitat for the species, per the statement.
Historically, these fish have matured to adulthood in the Pacific Ocean, then returned upstream to cold, fresh water in the mountains each spring. While basking in the chilly habitat, they used to wait out the warm summer months before spawning in the fall and starting the cycle all over again.
But dams and other barriers built along their historic rivers and tributaries have prevented the fish from swimming upstream to their mountain spawning grounds. Instead, they’re being trapped below the dams and forced to ride out the Central Valley’s scorching-hot summer months at lower elevations.
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Together with its tributaries, the North Yuba River can provide between 40 and 50 miles of ideal habitat for spring-run Chinook salmon, experts say. If the pilot project works, they hope to expand their efforts into a full reintroduction program. If all goes to plan, biologists would be able to “more than double the amount of available salmon habitat in the Yuba River watershed,” says Colin Purdy, the fisheries environmental program manager for the California Department of Fish and Wildlife’s north central region, in the statement.
“And that’s a huge win for spring-run Chinook salmon,” he adds.
Fall-run Chinook salmon—which swim upstream in the fall—are less affected by the dams than their spring-run cousins, because temperatures are typically cooler when they return to freshwater. They can also spawn downstream, per the San Francisco Chronicle.
But even fall-run Chinook are struggling right now. In 2023 and 2024, their numbers were so low that authorities banned commercial and recreational fishing off the California coast. This year could be another with no fishing, as 2024 fall runs in the Sacramento River and Klamath River watersheds were “far smaller than expected,” writes Seafood Source’s Nathan Strout.
