In the course of the ethohydraulic experiments (fish experiments), the fish protection effect of the FishProtector could be verified. The experiments have been performed at the experimental flume of the University of Bodenkultur (BOKU Vienna) in Lunz am See. The layout of the experimental flume is depicted in fig. 1. In a 3 m wide flume, wild fish (previously equipped with transponders) have been confronted with the FishProtector and a lateral bypass. The behaviour of the fish in proximity to the FishProtector has been documented and been analysed categorically. Besides experiments with the electrical fields of varying sizes, control experiments without an applied voltage have been performed and compared to the fish protection efficiency of the FishProtecor. The extension of the electrical field depends on the distance of electrodes as well as polarisation of the cables (cathode/anode).
Whilst a majority of the fish passed through the fish fence during not electrified reference experiments, the electrified setups showed a very good fish protection effect. The fish protection effect originates in the behaviour of the fish in combination with the hybrid barrier. The mechanical and also the behavioural barrier are decisive for the fish protection effect. The effect of the electric field depends on the voltage and the ratio of anodes to cathodes. This is clearly visible in the escape reactions of the fish. Videos impressively show the behavioural biologic effect of the pulsed field on the fish (bottom left).
Fish protection rates of up to 100% could be detected in ethohydraulic experiments with a clear spacing of 60 mm. The fish protection efficiency of the system is indirectly proportional to the count of passages through the FishProtector. Fig. 2 shows the number of screen passages for control experiments and experiments with an applied small respectively large electric field with 30 and 60 mm clear distance each.
In further experiments eels have been put to the test. Also here, the deterring effect of the FishProtector could clearly be verified .
Following videos show the fish behaviour in proximity to the FishProtector in the field laboratory in Lunz am See.
B. Brinkmeier, H. Böttcher, R. Tutzer und M. Aufleger, „Der Elektro-Seilrechen - Ein hybrides Fischschutzsystem für Wasserkraftanlagen,“ Wasserkraft & Energie, 2018.