AUTHORS: Christina M Mackey, US Geological Survey, Missouri Cooperative Fish and Wildlife Research Unit; Craig Paukert, US Geological Survey, Missouri Cooperative Fish and Wildlife Research Unit; Mark L. Wildhaber, US Geological Survey - Columbia Environmental Research Center; Allison A Pease, School of Natural Resources - University of Missouri; Jacob D Faulkner, US Geological Survey - Columbia Environmental Research Center; Robin D Calfee, US Geological Survey - Columbia Environmental Research Center
ABSTRACT: In the Mississippi River Basin and Great Lakes of the USA, behavioral deterrents that utilize acoustic stimuli are being considered for deployment in rivers to deter movement of invasive carps. Grass Carp Ctenopharyngodon idella are ostariophysans that possess an inner ear connection to the swim bladder allowing them to detect a broader range of frequencies compared to non-ostariophysans. This provides the potential for a greater range of response to acoustic stimuli. Previous research demonstrated the ability of Bighead Carp Hypophthalmichthys nobilis and Silver Carp H. molitrix to avoid acoustic stimuli in the laboratory. Prior to this study, limited data were available to support avoidance of acoustic stimuli by Grass Carp. We evaluated acoustic stimuli as a deterrent for Grass Carp by exposing two naïve juvenile carp together to a recording of one of three acoustic stimuli—a 10 second chirp (0.3 – 5 kHz), continuous 100 horsepower boat motor (0.6 – 10 kHz), and 3-6 beats/second percussion (0.375 – 23.5 kHz). Trials were conducted in a 720-liter indoor tank and Grass Carp behaviors (swimming velocity, proximity among individuals, time near stimulus) were measured for 10 minutes prior to (baseline behavior) and during the presentation of the stimulus (response). Grass Carp swimming velocity was statistically similar among stimuli, though carp in percussion trials appeared to show a slight increase. Compared to baseline behavior, Grass Carp spent more in close proximity when exposed to chirp stimulus and farther apart during exposures of boat motor stimulus. All three acoustic stimuli appeared to increase the time Grass Carp spent near the stimulus source, although responses varied among trials. Preliminary results suggest that Grass Carp response to acoustic stimuli presented in this study is complex and of relatively modest magnitude. The immediate value of acoustic stimuli as a deterrent is unclear from these results and warrants further study.
