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Basinwide Supplementation Evaluation

To test methodologies for improved abundance estimation, and to evaluate relative reproductive success (RRS) of natural-origin versus hatchery-origin salmon associated with supplementation and reintroduction programs operated by the tribes.

2009 set-up of DIDSON, computer, and generator at upstream exit of the Castile Falls fishway on the Klickitat River.

Project Goal

To test methodologies for improved abundance estimation, and to evaluate relative reproductive success (RRS) of natural-origin versus hatchery-origin salmon associated with supplementation and reintroduction programs operated by the tribes.

Impacts

Improved production programs and better escapement estimates.

Background

The use of supplementation to rebuild depressed salmon populations has been called into question due to concerns that the practice might lead to decreased productivity of the receiving natural population. The issue is of major concern to the treaty tribes, as they have been strong advocates of the use of supplementation to rebuild depressed and extirpated populations in their ceded lands. Numerous reports and initiatives have highlighted the need for improved and expanded monitoring of supplemented populations to better assess the long-term effects of supplementation and to inform how the practice can be applied for greatest benefit in fisheries management.

DIDSON mounted on a submergible stand.

Project Tasks

Objectives for the first year (Phase I) of the 10-year project:

1. To demonstrate use a Dual-Frequency Identification Sonar (DIDSON) for estimating spring chinook escapement in the upper basin of the Klickitat River. (3 years)
2. To complete development of a mark-recapture likelihood model which incorporates tag loss into the inference for population abundance. (1 year)
3. To conduct a relative reproductive success (RRS) study in a tribal supplementation project which lacks funds for the RRS study. (10 years)
4. To initiate RRS studies in 4 to 5 tribal programs involving reintroduction and supplementation of an extirpated stock, e.g., coho salmon in the Yakima, Wenatchee, Methow and Clearwater rivers, and spring Chinook in the Umatilla and Clearwater rivers. (10 years)