Evaluating the effects of a multi-modal deterrent on upstream passage by invasive carp and native species

Invasive carp, including silver carp (Hypophthalmichthys molitrix) and grass carp (Ctenopharyngodon idella), are increasing their range within the Mississippi River Basin, threatening native fishes and ecosystem function. We conducted a three-year field test of a multi-modal deterrent that uses sound, bubbles, and light to test its ability to impede upstream passage by invasive carp. The test was performed at a lock and dam on the Cumberland River, Kentucky, USA, using acoustic telemetry to track the movements of silver carp, grass carp, and several native fish species. When the deterrent was operating, the estimated probability of upstream lock passage was 53% lower (95% CI: 41 – 63%) for silver carp but 74% higher (95% CI: 3 – 190%) for grass carp compared to times when the deterrent was not operating. Paddlefish (Polyodon spathula) passage was reduced by 43% (95% CI: 71% reduction to 9% increase), although this was not statistically significant. We detected no significant effects on freshwater drum (Aplodinotus grunniens) or smallmouth buffalo (Ictiobus bubalus). However, sample sizes were small for these native species, limiting our ability to identify effects. Water temperature, tailwater elevation, and vessel lockages affected passage rates, although this varied among species.