Development of passage structures for adult Pacific lamprey at Bonneville Dam, 2006

Previous studies at Bonneville Dam have indicated that lamprey passage structures (LPSs) can aid passage ofmigrating adult Pacific lamprey Lampetra tridentata. A prototype LPS, which was operated during 2004-2005 in the Bradford Island Auxiliary Water Supply (AWS) channel, allowed adult lamprey to volitionally pass into the Bonneville Dam forebay. The first iteration of a lamprey collector at a fishway entrance was also fabricated and installed at Bonneville Dam in 2005. Our objectives in 2006 were to continue to modify and evaluate the performance ofthese structures. In 2006, the LPS was bolted to the walls ofthe AWS channel, and its original configuration was changed to include dual ramps for improved lamprey collection. Contract no. E96950021