Numerical simulation of electro-fishing in seawater

We evaluated the feasibility of an electro-fishing system using numerical simulations for laboratory tanks and the open sea. A non-homogeneous bi-dimensional electric-field model for water and fish based on discrete formulation of electro-magnetic field equations was developed using GAME (geometric approach for Maxwell equations) software. Current densities (^A/cm2) and voltage differences (V/m) were calculated for a fixed shape and spatial geometry of electrodes (one circular anode central to two symmetric linear cathodes 10 m distant from each other). Voltage gradients inside the fish and close to the body (head-tail potential difference and mean, maximum and minimum field modules) were determined. Tank and open sea environments were numerically described for single fish 10 cm or 30 cm long and for groups of 30 fish 10 cm long. In the open sea, a tension of 90 V at the electrodes and a water conductibility of 5 S/m resulted in an area of fish attraction (voltage gradient >10 V/m) of about 30 m2. Fish in the open sea and in groups had greater internal voltage differences than did fish in tanks and single fish.