On the Development of an Electric Fish Catcher

Abstract

Catching fish with electricity is found to be the easiest and most effective than other methods of capture. In practice, a galvanotropic response of fishes in an electrical field is evoked in developing fish catching devices. These devices are commercially available in many countries, not only to capture the fishes but also to study fish population. As such a device is not in practice in India, an attempt has been made to develop an electrical fish catcher by using indigenous materials to be effective for fresh water fishes. Tests were carried out on eight Indian fresh water food fishes to identify their significant behaviours with rising current densities and to determine the threshold values initiating those reactions especially, for the galvanotropic response. The test results were synthesized to develop a prototype electrical fish catcher. Its performance was tested with respect to initiating galvanotropic reactions of fishes (all species together). The developed unit has two components (1) a specially designed catcher (anode) and (2) DC power supply by stepping down and rectifying AC to continuous DC and pulsed DC of very low frequencies. Two electrical (continuous and pulsed DC), two environmental (standing and flowing water) and three field patterns (made by different electrode arrangements) were tested to find out the most effective use of the catcher electrode for bringing out directional forced swimming of fishes towards the catcher electrode. The field generated with an alternate polarity system has shown significant results (90–100%) for influencing the fishes to galvanotropic reactions.