Abstract
We evaluated a system to divert salmonid smolts tagged with passive integrated transponders (PIT) from the general migrant population as they passed through a juvenile collection system at a hydroelectric dam on the Snake River. Our goal was to maximize the diversion of PIT-tagged fish while simultaneously minimizing the diversion of untagged fish. The slide-gate system that was tested diverted 81% of PIT-tagged fish detected. The number of untagged fish entering the diversion system with every PIT-tagged fish was proportional to fish abundance and averaged one untagged fish for every PIT-tagged fish. Measures of descaling, injury, and mortality for all fish in the diversion system were similar to those for fish that were not diverted. These results established our basic PIT-tag diversion system as a major tool for conducting research on Snake River anadromous salmonids.