Evaluation of Infrasound and Strobe Lights for Redistributing Migrant Salmon Smolts in the McNary Juvenile Bypass: 1997

摘要

We assessed the use of infrasound and strobe lights for redistributing yearling and subyearling migrant salmonids away from dewatering screens in the McNary Juvenile Bypass System. Infrasound signals were generated using two devices: a pump with a rotary valve and reciprocating pistons. We evaluated the former device operating at 20 Hz in spring based upon differences in mean counts of migrant smolts across the channel during hourly sound%-on and sound-off treatments (-on=20). We evaluated the piston device operating at about 8 Hz in summer based on differences in mean counts of migrant smolts near the side dewatering screen during hourly sound-on and sound-off treatments (-on=9). We also tested three separate strobe light applications. In spring, we initially installed one strobe head (Flash Technologies AGL Series) in midchannel at the elevation of the top screen panels and aimed it toward the screened wall. Later in the spring, we deployed two strobe heads on the screened wall 4.3 and 7.3 m upchannel, respectively, from the downstream edge of the side dewatering screens. We evaluated effectiveness by comparing mean counts of migrant smolts across the channel during hourly strobe-on and strobe-off treatments (-on=18 for both applications). In summer, we installed two strobe heads behind the dewatering screens 7.3 and 11 m upchannel, respectively, from the downstream edge of the side dewatering screens. We evaluated performance based on differences in mean counts of smolts near the side dewatering screen during.