straying into other tributaries when they return as adults to spawn
The innovative project is led by The Bridge Group — a coalition of rice farmers, fishermen, water suppliers, researchers, and conservationists — in coordination with the U.S. Fish and Wildlife Service and the Tehama-Colusa Canal Authority.
The project places juvenile salmon from the Coleman National Fish Hatchery into large, predator-protected net pens within the Tehama-Colusa Canal forebay for three to four weeks. During this period, the fish are exposed to Sacramento River water, allowing them to imprint on the river’s unique chemical and olfactory cues, signals scientists say are critical for successful navigation back to natal spawning areas as adults.
“We believe imprinting will serve as another tool to help fishery managers determine best practices when deciding how and when to transport salmon to the San Francisco Bay, and ultimately, we hope to see a reduction in straying to maximize potential spawning returns in the upper Sacramento River,” said Roger Cornwell, Chair of the Sacramento River Settlement Contractors.
Many salmon produced at the hatchery on Battle Creek are trucked directly to the San Francisco Bay during poor river conditions. Because these fish do not migrate down the Sacramento River as juveniles, as they historically did during their outward migration, they miss key olfactory cues that help guide them back as adults. Elevated straying rates from trucked releases have, in some years, contributed to challenges in meeting hatchery broodstock collection goals.
“This collaborative effort represents the kind of forward-thinking, science-based approach our fishing communities have been calling for,” said George Bradshaw, President of the Pacific Coast Federation of Fishermen’s Associations. “By giving these fish the opportunity to imprint on Sacramento River water before release, we’re investing in stronger homing instincts, healthier spawning returns, and ultimately more stable salmon fisheries.”
The Tehama-Colusa Canal forebay provides a stable, secure, and highly managed aquatic environment well suited for this type of fisheries research. Its predictable water exchange, direct connection to Sacramento River water, and protection from high flows, debris, and vandalism make it an ideal location for temporary net pen rearing. The site’s proximity to both riverine and canal infrastructure also supports efficient fish transfer and release operations.
“TCCA is proud to partner with this forward-thinking coalition to test innovative solutions that support fishery managers, reduce straying, and help rebuild sustainable salmon runs for the long term.” said Zachary Dennis, Chairman of the Tehama-Colusa Canal Authority.
As part of the study design, juvenile salmon are fitted with coded wire tags at Coleman National Fish Hatchery and transferred to two separate net pens in the forebay. After the imprinting period, half of the fish are trucked and released into San Francisco Bay, while the remaining fish are released into Sacramento River waters near Battle Creek. A portion of the river-released fish are timed with managed pulse flows to further evaluate survival benefits.
“This imprinting program has tremendous potential if the proof of concept demonstrates that rearing Coleman Hatchery fish on the mainstem can reduce straying,” said John Atkinson with Golden Gate Fishermen’s Association, “We look forward to seeing the results as these fish return as adults in the coming years.”
Because Chinook salmon typically spend about three years in the Pacific Ocean before returning to spawn, the first results are expected in 2027 or 2028. In coordination with the U.S. Fish and Wildlife Service, a full scientific analysis will be conducted to evaluate project outcomes, identify best practices, and develop recommendations for future efforts.
“Projects like this show what’s possible when fishermen, farmers, water managers, and federal partners work together toward the shared goal of rebuilding and sustaining our salmon runs for future generations.” said James Stone, President of the NorCal Guides and Sportsmen’s Association.
The Bridge Group includes representatives from the Pacific Coast Federation of Fishermen’s Associations, Golden Gate Fishermen’s Association, NorCal Guides and Sportsmen’s Association, Northern California Water Association, the Sacramento River Settlement Contractors, and the California Rice Commission. Together, the group represents thousands of square miles of farmland across Northern California and hundreds of fishing businesses and guides operating from the Sacramento River to Monterey Bay and beyond the Oregon border. The U.S. Bureau of Reclamation and UC Davis Center for Watershed Sciences also provide technical and science support to the Bridge Group’s efforts.
