Technology developed for diverting passive integrated transponder (PIT) tagged fish at hydroelectric dams in the Columbia River Basin

Data collected on juvenile salmonids tagged with passive integrated transponder (PIT) tags as they migrate seaward through the Columbia River Basin provide fisheries managers and resource agencies with valuable information to evaluate the effectiveness of current management actions and restoration strategies. The development of new technology to route PIT-tagged fish through multiple alternative pathways as they pass through the interrogation systems at the fish bypass/monitoring facilities at hydroelectric dams provides another valuable real-time tool to monitor and evaluate the migration, passage, and survival of PIT-tagged juvenile salmonids in the basin. The authors describe the current computer program and gate-control technology for routing fish, and provide detailed descriptions of three new types of fish-diversion gates. The comparative advantages and disadvantages of each gate are discussed. The prototype of a fourth diversion gate, with only one moving part, is also described.