Passage behavior and survival for radio-tagged yearling chinook salmon and juvenile steelhead at Lower Monumental Dam, 2007

In 2007, NOAA Fisheries evaluated passage behavior and estimated relative survival for radio-tagged river-run hatchery yearling Chinook salmon Oncorhynchus tshawytscha and juvenile steelhead O. mykiss at Lower Monumental Dam on the Snake River. Fish were collected, PIT tagged, and surgically implanted with a radio transmitter at Lower Monumental Dam. Treatment groups were comprised of 663 yearling Chinook salmon and 665 juvenile steelhead released 7 km upstream from Lower Monumental Dam. Reference groups were comprised of 637 yearling Chinook salmon and 646 juvenile steelhead released into the tailrace of Lower Monumental Dam. Releases occurred during both daytime and nighttime operations for 25 d from 1 to 25 May. Project operations during the evaluation included bulk spill 24 h per day. River flow, percent spill, and tailwater elevation during releases averaged 79 kcfs, 27%, and 439 ft msl, respectively. Contract no. W68SBV92844866