WSU is helping California tribe to bring salmon home

A collaborative conservation project is working to restore Chinook salmon to ancestral waters in Northern California, with researchers from Washington State University playing a key role in ensuring the fish can safely return.

The effort is part of a partnership between WSU scientists and the Winnemem Wintu Tribe to help reintroduce Chinook salmon to the McCloud River, where the species disappeared in the 1940s following the construction of Shasta Dam, which blocked access to historic spawning grounds.

The restoration work begins far from California — at remote sites in New Zealand — where salmon descended from McCloud River fish were sent more than a century ago. Researchers collect tissue samples from select salmon and transport them through a complex international shipping route back to Washington State for disease testing.

The samples travel thousands of miles across multiple airports and must reach Washington Animal Disease Diagnostic Laboratory within 48 hours. There, laboratory specialists test the samples for a broad panel of aquatic pathogens, including viruses, bacteria, fungi, and parasites. The laboratory is one of the few public institutions capable of performing the full range of required testing to meet U.S. and state biosecurity standards for species reintroduction programs.

The testing is a critical step before salmon eggs can be transported to California. Federal and state regulations require disease screening to prevent introducing harmful pathogens into native ecosystems. WADDL is approved by the United States Department of Agriculture Animal and Plant Health Inspection Service to conduct diagnostic testing for aquaculture export health certification.

The restoration initiative is part of the Winnemem Wintu Salmon Rematriation Project, which focuses on three major goals: transporting fertilized eggs from New Zealand salmon populations back to California, improving fish passage around Shasta and Keswick dams, and restoring habitat conditions along the McCloud River.

In 2023, the Winnemem Wintu Tribe entered a co-management agreement with the California Department of Fish and Wildlife, formally recognizing the tribe’s role in guiding restoration efforts for salmon populations and river ecosystems.

Before any fish can be reintroduced to California waters, they must pass rigorous health screening to meet environmental safety requirements. Researchers say no single laboratory in California currently provides the full suite of diagnostic testing required for this project, making WSU’s laboratory partnership essential.

The work also involves cultural and ceremonial elements. In New Zealand, sampling begins at multiple river locations with ceremonial acknowledgments honoring the waterways, mountains, and ancestral connections of the participating tribes, including New Zealand’s Ngāi Tahu.

Researchers and cultural leaders say the ceremonies reflect the cultural significance of salmon restoration, symbolically guiding the fish back to ancestral waters while also acknowledging ecological stewardship traditions.

Once collected, samples are transported by air from regional airstrips to Christchurch, then through international flights connecting Auckland, San Francisco, Seattle, and Spokane before arriving in Pullman for testing.

The project has already completed one full year of pathogen testing and must complete at least two consecutive years of monitoring before import permits for fertilized eggs can be approved.

Scientists and conservation partners are working quickly because Chinook salmon populations in New Zealand have been declining as ocean and river temperatures rise. Conservation estimates suggest wild population numbers have dropped dramatically in recent years, raising urgency around the restoration timeline.

Partners involved in the project remain optimistic that testing and regulatory approvals can be completed soon, allowing the restoration effort to move closer to reintroducing salmon to their ancestral habitat.

The project represents a blend of conservation science, cultural preservation, and international cooperation aimed at restoring both ecological balance and historical relationships between people, land, and species.