Experimental Evaluation of a Modular Electric Barrier for the Deterrence of Invasive Carp

We conducted a series of studies to assess the effectiveness of an electric barrier in deterring the movements of freshwater fish. Fish responses (detections·individual^-1·hr^-1 within the 3 m exclusion zone) were quantified for a mixed assemblage of native and nonnative fishes within 0.4 ha ponds. Additionally, we mapped the surface voltages generated by the electric barrier in a nearby stream. The electric barrier (operated at 10 kW) was effective at deterring native and invasive fishes, as > 99% of all fish detections within the exclusion zone occurred while the electric barrier was off. However, some fish detections occurred while the system was operated at full power, indicating the electric barrier was not 100% effective. A follow-up study found that fish responses differed between low (3.6 kW), medium (6.6 kW), and high (10 kW) field strengths, with smallmouth buffalo Ictiobus bubalus exhibiting a greater sensitivity to the low setting than bighead carp Hypophthalmichthys nobilis and silver carp H. molitrix. Maps of the surface voltages within a nearby stream indicated that the electric barrier was strong enough to deter silver carp (> 1 V/cm). However, the surface voltages quickly dissipated upstream and downstream of the electrodes. Overall, the electric barrier appears to be an effective tool that can be used to combat the spread of invasive fishes in freshwater environments. However, more evaluations are needed to test how the system performs in different conditions and to identify whether fish of varying sizes or life stages respond similarly.