Bigheaded Carp Behavior and Bioacoustics

Silver (Hypophthalmichthys molitrix) and bighead (H. nobilis) carp dominate the Mississippi River Drainage, outcompete native species, and continue to expand northward. Silver carp demonstrate an unusual jumping response to boat traffic. Understanding this behavior is important from a behavioral standpoint and critical to developing effective control methods. Field observations of silver carp jumping frequency, orientation, and direction in response to fast moving (16 – 32 km/hr) boats and broadband (0.6 – 10 kHz) sound characterized jumping behavior. Controlled experiments, in outdoor concrete ponds (10 x 5 x 2 m), investigated the sensory biology of both carp species. Bigheaded carp behavior in response to pure tones (500 – 2000 Hz) and broadband sound was assessed. The fish habituated quickly to pure tones (after 1-2 trials) however, they exhibited negative phonotaxis in response to the broadband sound. 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 bigheaded 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, the Minnesota Environmental Trust Fund, and the University of Minnesota Duluth.