Willamette Spring Chinook Project
The Willamette and Sandy rivers support intense recreational fisheries for spring Chinook salmon (Oncorhynchus tshawytscha). Fisheries in these basins rely primarily on annual hatchery production of 5-8 million juveniles. Hatchery programs exist in the McKenzie, Middle Fork Willamette, North and South Santiams, Clackamas, and Sandy rivers mainly as mitigation for dams that blocked natural production areas. Some natural spawning occurs in most of the major basins and a few smaller tributaries upstream of Willamette Falls.
The Oregon Fish and Wildlife Commission adopted the Wild Fish Management Policy to reduce adverse impacts of hatchery programs on wild native stocks. The main goal of the policy is to protect the genetic diversity of these stocks recognizing that genetic resources are a major component, not only in sustaining wild stocks, but also in perpetuating hatchery programs and the fisheries they support.
In the past, spring Chinook salmon management in the Willamette and Sandy basins focused on hatchery and fish passage issues. Limited information was collected on the genetic structure among basin populations, abundance and distribution of natural spawning, or on strategies for reducing risks that large hatchery programs pose for wild salmon populations. This study is being implemented to gather this information.
This Willamette Spring Chinook Project hopes to help managers collect information that will lead to a management strategy for spring Chinook salmon in the Willamette and Sandy basins that (1) protects the genetic integrity of natural populations, and (2) maintains sport and commercial fisheries and the programs that support them. A research proposal was created in 1996 with five objectives:
Objective 1. Determine the numerical status of existing natural populations and develop methods for monitoring that status. Determine if these populations belong to one or more gene conservation groups.
Task 1.1 Determine if Sandy and Clackamas spring Chinook belong to the same gene conservation group as spring Chinook above Willamette Falls.
Task 1.2 Estimate the proportion of wild fish in the spawning populations.
Task 1.3 Develop annual indexes for monitoring natural spawner abundance of spring Chinook.
Task 1.4 Establish escapement goals for natural production in Willamette River sub-basins and in the Sandy River.
Objective 2. Decrease mortality of wild fish in fisheries by determining feasibility of catch and release sport fisheries and by exploring options for reducing mortality in commercial fisheries.
Task 2.1 Estimate sport angling mortality of caught and released fish.
Task 2.2 Estimate mortality that would occur from fin-clipping hatchery fish so that anglers could tell hatchery from wild.
Task 2.3 Evaluate other mass marking techniques so anglers can identify hatchery adults in sport fisheries.
Task 2.4 Explore options with Salmon Program Managers and Columbia River Management Program for reducing mortality of wild fish in commercial fisheries.
Objective 3. Reduce the risk that large hatchery programs pose for natural populations by developing ways of decreasing interactions between wild and hatchery Chinook in streams and by determining need for more wild fish in hatchery broodstocks.
Task 3.1 Evaluate fishery contribution and straying from net-pen releases below the falls.
Task 3.2 Determine if hatchery fish released in the fall over-winter, potentially competing with wild spring Chinook.
Task 3.3 Explore options for trapping hatchery spring Chinook above or near traditional fisheries but below wild spawning areas.
Task 3.4 Determine need and look at ways of incorporating wild fish into hatchery broodstock.
Task 3.5 Look at overlap of spawning between fall and spring Chinook.
Objective 4. Protect existing natural production areas by defining temporal and spatial use patterns by life stages of spring chinook and identify the habitat/environmental attributes conducive to that use.
Task 4.1 Document distribution of spawning and rearing, timing of emergence and migration in basins used by spring chinook.
Task 4.2 Identify spring Chinook habitat and environmental attributes.
Task 4.3 Identify life histories and the habitat/environmental features critical to maintaining them.
Objective 5. Increase natural production by improving habitat in existing production areas and by re-establishing populations where they were found historically.
Task 5.1 Identify opportunities to re-establish populations and to improve habitat
Task 5.2 Estimate the potential of Willamette and Sandy river basins (post-dam) to produce wild spring Chinook.
Task 5.3 Evaluate current efforts to re-establish spring Chinook (South Santiam River above dams, Thomas, Crabtree, and Calapooia creeks).