Bioacoustic Control and Management of Invasive Silver Carp

Silver carp (Hypophthalmichthys molitrix) dominate large regions of the Mississippi River Drainage, outcompete native species, and continue to expand northward threatening the Great Lakes. Understanding silver carp behavior is critical to determine effective techniques for controlling this harmful species. Field observations and recordings in Havana, IL were completed to correlate silver carp's response to the sound generated by outboard boat motors. Controlled experiments, in restricted access outdoor concrete ponds (10 x 5 x 2 m), investigated the sensory biology of silver carp. The concrete ponds were outfitted with overhead cameras, speakers, and hydrophones. Pure tones (500-2000 Hz) and field recordings of outboard motors were broadcast to silver carp and their behavior tracked. Silver carp habituated quickly to pure tones (after 1-2 trials) however, they regularly exhibited negative phonotaxis in response to outboard motor sounds. By alternating the speakers, silver carp movement was consistently directed away from the sound source to the opposite end of the pond. This research suggests that sound can be used to alter the behavior of silver carp with implications for deterrent barriers or other uses (e.g., herding fish to increase harvest). Research was supported through the U.S. Geological Survey and University of Minnesota Duluth.