Laboratory experiments demonstrate that bubble curtains can effectively inhibit movement of common carp

Although bubble curtains have been proposed many times as practical and inexpensive solutions to hinder the movement of invasive fish, few studies have examined why or how they might work. By understanding how bubble curtains influence fish behavior, management tools could be developed to control movement of invasive fish. In this study, the common carp (Cyprinus carpio L.) was used to examine the performance of three different bubble curtains (fine-, graded-, and coarse-bubble) and acoustically enhanced systems in an indoor channel. Trials revealed that the graded- and coarse-bubble systems reduced common carp passage across the curtain by 75-85% in both up- and down-stream directions. Concurrent acoustic field measurements revealed that these bubble curtains generated sound near 200 Hz at approximately 130 dB (ref 1 μPa), well above the common carp hearing threshold. Further testing with speaker arrays and lighting indicated that carp avoidance of the bubble curtain involved responses to sound and fluid motion rather than visual cues. Although field tests are warranted, our results suggest that bubble curtains may be a viable and inexpensive deterrence system to limit common carp movement.