Go, Carp. Go!: Efficacy of Waterguns, Sound, and CO2 to Deter Bigheaded Carp

Invasive Bighead and Silver Carp have moved throughout the Mississippi River Basin and are now threatening entrance into Lake Michigan. An electric dispersal barrier is the only measure in place to limit upstream movement of fish. The USGS has been evaluating three alternative techniques for deterring upstream passage of carp: seismic pressure waves (i.e., water guns), complex sound, and CO₂. To determine the efficacy of these deterrents, a 106 foot-wide mock lock chamber was erected out of block nets in a backwater of the Illinois River. Paired trials (control then deterrent) were conducted for each deterrent type (sound and CO₂ = 3, seismic = 2). Thirty-two bigheaded carp were tagged with HTI acoustic transmitters and monitored with an extensive acoustic array. Each trial was run for 24 h followed by a 24-h period of no activity to allow fish to exit the area. During the deployment of deterrents, we assessed 1) the number of fish that migrated through the mock lock chamber; 2) how many times an individual fish migrated through the mock lock chamber; 3) the probability of a fish to be in the mock lock chamber; 4) how each deterrent affected fish swimming behavior; and 5) spatial distribution.