Wenatchee Basin Coho Energetics Study

Our first objective was to understand how the extended migration is affecting energy storage prior to migration and the use of that energy by Wenatchee River coho to successfully return to the Wenatchee River. It has been speculated that some fish returning to the Wenatchee River do not possess adequate energy stores, primarily in the form of lipids, and consequently do not reach their destination. Hence, successful migrants may represent fish selected for their tendency to: (a) store more energy prior to a longer migration; (b) use available energy stores more efficiently; or (c) combine these strategies. As reviewed in the previous chapter, this hypothesis stems from evidence that pre-migratory energy stores are positively correlated with migration difficulty and of the efficient use of available energy among and within Pacific salmon populations. We predicted that successful Wenatchee River coho would have higher lipid levels than their lower river ancestors at a common location along the Columbia River and use a higher percentage of lipids to achieve migration.
Our second objective was to determine whether morphology of the developing upriver coho population is being influenced by the extended migration. Given that wild populations traveling long distances are often smaller in size and stature than down river populations, and possess proportionally reduced secondary sexual traits and median fins, selection presumably favors fish with the proper combination of size and shape, forming hydrodynamic qualities that optimize energy use during upriver migration. With a strong mechanism for selection and reproductive isolation, the initial rate at which the Wenatchee River population develops may be quite rapid. The presence of altered morphological traits may reveal how the population as a whole is responding to the rigors of migration. We predicted that successful Wenatchee River migrants would exhibit diminished morphological traits when compared to their original parent stock.
Our third objective was to elucidate the effects of a constrained energy budget on ovary mass, individual egg weights and fecundity (egg number) in Wenatchee River coho. Faced with an arduous migration, less energy may be allocated to total ovarian development resulting in decreased ovary masses, egg weights and fecundities. These traits are closely tied to the fitness of Wenatchee River coho and the rate at which they will evolve is not clear. In light of experiments that positively demonstrated that migration comes at a cost to reproductive development, we sought evidence of diminished total ovary mass, egg weight and fecundity in successful Wenatchee River female migrants would be diminished as a result of the extended migration.

While there is an increasing body of literature surrounding the genetic risks of supplementation programs (Busak and Currens 1995; Miller and Kapuscinski 2003; Ford et al. unpublished manuscript), we have found very little research documenting naturalization or local adaptation of a domesticated hatchery stock.
Coho restoration in the Yakima, Wenatchee, and Methow Rivers has long been a part of the Tribal Restoration Plan. The lack of locally adapted populations in all three basins is the biggest challenge to coho reintroduction. The Wenatchee Subbasin Plan Guiding Principle 11 states that reintroduction or supplementation programs should select an appropriate stock or locally adapt a donor stock where a local stock no longer exists (NPCC 2004a). The proposed project is designed to measure the rate of adaptation through the phenotypic expression of energy allocation. This information will provide an indicator if the broodstock development process is working.
Expanding the knowledge of Pacific salmon energetics has broad research and management implications for recovery of listed species, and as such, could directly benefit many aspects of the Councils Fish and Wildlife Program. In guiding hatchery management actions, models such as the All Hs Analyzer (AHA; Mobrand Biometrics) can be used to project the results of hatchery management scenarios. Results of these scenarios are in part based upon assumptions regarding the rate of adaptation resulting from changing influence from either the natural or hatchery environment. Our proposal presents a study which could provide researchers the opportunity to closely examine the rate of adaptation and learn how much change in the phenotypic expression of traits can occur in one generation.