Could Noise Help Protect the Great Lakes Basin?
Scientists with the University of Minnesota Duluth (UMD) and the U.S. Geological Survey recently studied silver carps’ reaction to sound at the USGS Upper Midwest Environmental Sciences Center (UMESC) in La Crosse, Wisconsin. The researchers found that silver carp reacted strongly to complex noises such as underwater recordings of boat motors, consistently swimming away up to 37 times in succession. The results are published in the journalBiological Invasions.
“Silver carp threaten many waterways in the Great Lakes basin by competing with native species,” said USGS UMESC Director Mark Gaikowski. “Understanding silver carp behavior is critical for determining effective techniques to minimize the ecological and economic damage of this invasive species.”
Brooke Vetter, a UMD graduate student and lead author of the report, positioned speakers at both ends of outdoor concrete ponds. She compared the carps’ response to pure tones, which sound like a dial tone, to their response to more complex noises. The fish adjusted to the pure tones, never swimming away more than two consecutive times, but continuously responded negatively to complex sound.
“Our complex noise findings suggest that certain sounds could be used to divert silver carp away from strategic points on waterways or herd them into nets,” Vetter said.
Results from this study have provided the foundation for the UMD, USGS and Illinois Natural History Survey to conduct field trials testing the efficacy of complex noise as a silver carp control tool in the Illinois River.
Silver carp are reshaping river ecosystems through competition with native fish and mussels for the plankton that form the base of aquatic food webs. In regions of the Illinois River where carp populations are the most abundant, carp account for a large percentage of the river's biomass.
Silver carp also present a danger to boaters because fish as large as 20 pounds can jump 10 feet out of the water, causing injury and damaging boats.