Coho Reintroduction in the Upper Columbia River-Adaptively Managing a Forgotten Species
By the end of the 20thcentury, indigenous coho salmon no longer occupied the mid- and upper-Columbia river basins. Several factors contributed towards their extirpation, which included but not limited to construction of mainstem Columbia River hydropower projects, habitat degradation, irrigation, release locations, harvest management, and hatchery practices. Since this extirpation, attempts have been made to re-initiate production within the Upper Columbia but none of these efforts were intended to restore a species that had become a lessor priority with ESA listings of several depressed spring Chinook and steelhead stocks.
In the mid-90's, Yakama Nation held a vision of restoring coho salmon with the primary focus of creating self-sustaining populations that, over time, would have successfully adapted to their unique environmental conditions. Studies have been conducted to determine feasibility of reintroduction, which began in the Methow basin in 1996 followed by the Wenatchee basin in 1999. Reintroduction feasibility was focused on addressing two primary concerns from co-managers; 1) whether a broodstock could be developed from lower Columbia River coho stocks whose progeny could survive in increasing numbers to return as adults and 2) initiate natural reproduction in areas of low risk to sensitive species and in other select areas to study interactions risks with sensitive species.
Since project initiation, feasibility questions have been answered with little to no adverse impacts to listed populations. A master plan, developed as the acting mandate for program guidance, emphasized adaptive management in order to develop a geographically isolated, population that was locally adapted and naturally reproducing. This distinct, phased approach is an attempt to develop that population over time through encouraging adaptation towards predicted habitats using biological 'benchmarks' to assess success. To date, the Methow program has met both broodstock development requirements while the Wenatchee is close to doing the same. The fall of 2013 will document a monumental program achievement as the Methow program begins to collect broodfish for an expansive, implementation phase that will encourage the naturalization process.
Positive programmatic trends continue to be observed as coho adult escapement increases in both basins, as documented with the 2011 upper Columbia returns numbering over 30,000 individuals. This approach of species reintroduction is also occurring within other Yakama Nation programs (e.g.-Cle Elum sockeye and Yakima River summer Chinook) with the intent of returning fish that were once historically predominant and significant, not only culturally but to restoring ecological function to many of these systems.