To prevent entrapment of fish in large Archimedean screw turbines, a fish deterrence system was installed at the entrance of the hydro-power plant. The deterrence system consists of 4 GRP or steel tubes in which 3 times 5 LED lamps are placed that shine outward through curved glass screens. The lights are of the type FF-12-I (Fischflow Innovations) and flash at a frequency of 1Hz. In this study we analyze the behavior of silver eel in the area around the fish deterrence system with 2D acoustic telemetry (180 kHz, HR2 Innovasea receivers).