Special Considerations in Design of Barriers for Invasive Fish Control

Non-physical barrier (NPB) systems that are used for limiting the movements of invasive non-native fish have the objective not necessarily of achieving total exclusion of fish from protected waters but of reducing in-migration to levels below which they would not be able to establish a viable population. Effective NPB design here requires, first of all, a very high level (near 100%) of fish exclusion efficiency, and since the non-natives may be resident on the unprotected side of the barrier, resistance to repeated challenges by the same fish. The NPB must also be capable of maintaining high efficiency under all plausible operating conditions, including flood or drought events, boat and barge passage and other perturbations. High performance of NPBs can in some cases be best achieved by using multiple stimuli. The barrier scoping, design and performance –testing issues are discussed.