A low-voltage electric fish guidance system—NEPTUN

• A low voltage electric fish guidance system (NEPTUN) technical paramterers are described.
• Results of laboratory experiments with 14 fish species of various sizes are presented.
• The 93.8–98.2 efficiency of the system in stopping fish at flow velocity below 0.20 m is proved.

This paper presents a type of electric barrier for fish, which can be used to deter fish from water intakes and to guide them into fishpass channels. The barrier was designed to continuously generate an inhomogeneous low-voltage (50–80 V) electric field. It consists of two arrays of steel electrodes (positive and negative) anchored to the substrate, with floating buoys attached at the top of each electrode to maintain their vertical position. Field strength increases continuously from the positive electrode array toward the negative electrodes. The resultant electric field does not stun fish, but stimulates their neuromuscular system, allowing them to escape. With input power of 0.43–0.45 kWh and power consumption of 0.0018 kW m−2, the system is inexpensive to operate, and safer for fish and other aquatic organisms than classic electric barrier designs. Laboratory tests of the barrier with 14 fish species of various sizes indicate that for flow velocities less than 0.20 ms−1, 93.8–98.2% of the fish did not pass the NEPTUN barrier.