Salmon are swimming again in the North Yuba River for the first time in close to a century. The fish are part of an innovative pilot project to study the feasibility of returning spring-run Chinook salmon to their historical spawning and rearing habitat in the mountains of Sierra County.
In late October 2024, the California Department of Fish and Wildlife (CDFW), in partnership with the Yuba Water Agency, National Oceanic and Atmospheric Administration (NOAA) Fisheries and the U.S. Forest Service, injected spring-run Chinook salmon eggs over a 12-mile stretch of gravel riverbed of the North Yuba River along Highway 49 just east of Downieville.
The fertilized eggs arrived in coolers from CDFW’s Feather River Fish Hatchery in Oroville. Using a proven technique used by other agencies but never before attempted by CDFW, fisheries scientists created dozens of man-made salmon redds, or nests, using a hydraulic injection system to clear the intended nests of silt. Scientists then carefully deposited the eggs up to a foot and a half deep within the gravel to mimic the actions of spawning adult salmon. The intent is for the salmon to emerge from the gravel and grow as wild salmon would.
Four months after hydraulic egg injection occurred in the North Yuba River, salmon have begun to hatch and have turned up in a rotary screw trap installed several miles downstream of the egg injection sites to collect out-migrating juveniles. The first young fish were seen in the trap on Feb. 11. The young fish are being trucked downstream of Englebright Lake and released into the lower Yuba River to continue their migration to the Pacific Ocean.
“The North Yuba represents a really unique location for us. Between the mainstem and its tributaries there is somewhere around 40 to 50 miles of habitat that is ideal for spring-run Chinook salmon for holding, spawning and rearing,” said Colin Purdy, Fisheries Environmental Program Manager for CDFW’s North Central Region. “If we can develop this pilot effort into a full reintroduction program, we would be able to more than double the amount of available salmon habitat in the Yuba River watershed. And that’s a huge win for spring-run Chinook salmon.”
Central Valley spring-run Chinook salmon are a state and federally listed threatened species. They’ve been locked out of the North Yuba River’s cool, clear waters since the construction of Englebright Dam in 1941 and the subsequent construction of New Bullard’s Bar Dam in the early 1960s. The North Yuba’s cool waters are perhaps the most high-quality and climate-resistant habitat in the Central Valley for this species.
Spring-run Chinook salmon, once the most abundant of all of California’s various salmon runs, have a unique life history that makes them especially vulnerable to warming conditions on the Central Valley floor. After growing to adulthood in the ocean, the fish typically return to freshwater in the spring, seek out cold water habitat upstream as far as they can go, and hold over the summer months before spawning in the fall. Many tributaries that historically supported spring-run Chinook salmon now have dams and other barriers, and the salmon trapped below dams must now survive the Central Valley’s scorching summer heat. Juvenile spring-run Chinook salmon, meanwhile, can spend up to a year in freshwater before out-migrating to the ocean.
All the eggs and resulting salmon in the North Yuba River pilot project have been DNA tagged for identification, a practice known as “parentage-based tagging.” Every individual salmon in the North Yuba River can be identified and linked genetically to the exact set of parents that produced it during spawning at the Feather River Fish Hatchery in September.
“This is habitat that salmon haven’t been into for a long time so we have very little data to understand how salmon will respond,” Purdy said. “By injecting these eggs into multiple locations in the North Yuba River, we’re going to be able to look at how long it takes for eggs to hatch and turn into yolk sac fry, how do they rear, how fast do they grow, when and where do they rear as juvenile salmon in this new habitat. So there are a number of different things that we’re going to be able to learn from this.”
The North Yuba River pilot project is one of a number of major initiatives underway in California to return salmon to historic, cold-water habitat upstream of dams and other fish barriers, which is seen as critical to their long-term survival in California and a key priority of Gov. Gavin Newsom’s California Salmon Strategy for a Hotter, Drier Future and NOAA Fisheries’ actions that will support the recovery of this species.
The reintroduction of endangered winter-run Chinook salmon to the McCloud River above Shasta Reservoir and removal of dams on the Klamath and Eel rivers are three other major salmon initiatives.
Unlike the Klamath and Eel rivers, there are no plans to remove dams on the Yuba River as they still serve critical water supply and flood protection functions.
Any formal, ongoing reintroduction of spring-run Chinook salmon to the North Yuba River would require a trucking component as occurs now with winter-run Chinook on the McCloud River and as takes place in the Pacific Northwest.
In addition to supporting reintroduction, a framework agreement among CDFW, NOAA Fisheries and the Yuba Water Agency calls for improved fish passage past the U.S. Army Corps of Engineers’ Daguerre Point Dam lower in the watershed, which would significantly improve passage for all migratory fish species in the lower river and open up an additional 12 miles of healthy holding and spawning habitat for both green and white sturgeon, salmon, steelhead and rainbow trout.
