Deterrence System to Protect Fish at Hydropower Dams in Brazil: Prospective and Potential Use

Fish mortality in turbines is a problem of large proportions in Brazil with registered events where up to 10 tonnes of fish were killed. The most common scenario described for fish kills in Brazil is related to fish moving upstream and getting trapped inside the turbine draft tube during maintenance events. Therefore, the interest of hydropower companies in the development of deterrence systems to stop movement of fish inside the draft tube is increasing. Although little information is available on the behavior of Neotropical fishes exposed to deterrent systems, lab tests with mandi-amarelo allowed us to have a prospective for the possible use of two different systems: i) strobe light and ii) electrical barrier. Several studies showed that flow regimes can reduce significantly the success of a deterrent system, especially for the scenario where fish is moving downstream with the flow. The potential use of a non-physical barrier for the Brazilian scenario increases due to the need of stoping fish moving upstream, thus, against the flow. In this case, the flow would enhance the deterrence effect by dragging fish away from the draft tube, reducing the probability of entrapping fish during turbine maneuvers.