Reaction of Chinook Salmon, Northern Pikeminnow, and Smallmouth Bass to Behavioral Guidance Stimuli
Behavioral Technologies for Fish Guidance: American Fisheries Society Symposium
American Fisheries Society
We examined the response of three fish species to various behavioral stimuli during cage tests conducted in the forebay of the Roza Dam irrigation diversion on the Yakima River, Washington. Wild yearling chinook salmon Oncorhynchus tshawytscha were evaluated for responses to strobe light, drop light, and infrasound stimuli that might be used to guide smolts at screening facilities at Roza Dam. We tested northern pikeminnow Ptychocheilus oregonensis (strobe light, infrasound) and smallmouth bass Micropterus dolomieu (strobe light) to determine if these predators could be repelled. Behavioral responses of chinook salmon to all stimuli were evaluated under daylight, dusk, and nighttime light conditions. All tests with northern pikeminnow and smallmouth bass were conducted at night. We observed strong avoidance by chinook salmon smolts to strobe light during 60-min exposures at night. Little or no reaction was observed in similar tests conducted during daylight hours and at dusk. Avoidance responses during nighttime tests were characterized by rapid movement to the end of the cage opposite the active strobe light. Chinook salmon responses were greatest when the downstream light was operated and when the strobe lights were positioned closer to the test cage. Smallmouth bass response to strobe light was similar to chinook salmon. We observed less avoidance of strobe light by northern pikeminnow. Chinook salmon exhibited minimal response to the drop light and did not respond to infrasound. Northern pikeminnow strongly avoided three of the four infrasound frequencies that were evaluated. These results indicate that strobe lights have potential to repel chinook salmon smolts and smallmouth bass at night. Infrasound generators and drop lights are not considered viable alternatives for guiding chinook salmon smolts at Roza Dam. Infrasound may have potential for repelling northern pikeminnow from areas where smolt predation may be high (e.g., bypass outfalls).