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Project 2007-273-00 - Evaluate the effects of hyporheic exchange on egg pocket water temperature in Snake River fall Chinook salmon spawning areas
Evaluate the effects of hyporheic exchange on egg pocket water temperature in Snake River fall Chinook salmon spawning areas
Summary:
The research to be conducted under this proposal will evaluate relationships among river discharge, hyporheic zone characteristics, egg pocket water temperature, and emergence timing of Snake River fall chinook salmon.
Proposer:
None
Proponent Org:
Pacific Northwest National Laboratory (Govt - Federal)
The proposal lays out a case for developing a better understanding of the effects of surface-hyporheic water exchange on the developmental rate and survival of fall Chinook eggs and alevins below the Hells Canyon dam complex, and whether operation of the dams can generate flow conditions that improve survival and accelerate embryonic development. The working hypothesis is that water releases from upstream storage reservoirs and the timing of spill can be adjusted to increase egg survival and cause fry to emerge earlier.
In general, the objectives are clearly stated and specific timelines are given. Our main concern had to do with sample size. Fourteen sites, 25% of the total number of "most used" spawning areas, have been selected (a map would have been helpful). While this seems like a plausible number of sites for a general survey of Chinook reproductive success, the proposal did not really address the question of how many sites would be needed to achieve the overall objective of developing a better understanding between egg survival, hyporheic flow dynamics, and modified reservoir operations. At $10-15K per sample site per year, it is important to sample enough sites to answer the central questions, but at some point adding sites may not yield much additional information. Nevertheless, as long as sample size is reasonably justified, this should be a worthwhile effort.