Smolt Passage Behavior and Flow-Net Relationships in the Forebay of John Day Dam
behavior, chinook, fish distribution, fish passage, John Day Dam, migration, monitoring, salmon, smolt, smolt passage, sockeye salmon, spillway, steelhead
During 1983, the research program had three separate but complementary phases - monitoring current patterns in the forebay, defining fish distribution with purse seine sampling, and describing the migration routes of salmonid smolts using radio tracking techniques. Preliminary results from the radio-tracking and purse seining operations in FY83 suggest that the discharge from the John Day River and the turbid plume it forms in the forebay may have a pronounced effect on the distribution of smolts, especially chinook and sockeye salmon, as they approach the dam. The implication of these data is that the plume may be shunting salmon toward the Washington (spill) side of the river where they would be more susceptible to spill passage. This resulted in higher spill passage of tagged chinook salmon than the proportion of water being spilled. In contrast, spillway passage of steelhead not influenced by the plume is approximately the same as the proportion of water being spilled. These findings are based on limited data and must be considered preliminary at this time. Data describing the current patterns have just recently been reduced to a usable format and have not yet been correlated with findings from radio tracking and purse seining. Such data will be incorporated into an overall analysis of the relations of current patterns and John Day River discharge to fish migration patterns. Representative examples of prevailing current patterns during the spring migration have been completed and are included in this document.
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