Department of Fisheries Resource Management, Tokyo University of Fisheries, Minato, Tokyo 108-8477, Japan
We studied the scoop net fishery for ayu in Lake Biwa. We investigated the fishery management problem when the engine power of fishing boats is classified into three classes. The equilibrium net profit was obtained as the solution of a non-cooperative dynamic game. We investigated the behavior of the solution using simulations. When the initial population size was lower, the lowest class was profitable. However, the highest classes became profitable, as the initial population size increased. The total net profit for middle class fishermen over ten years, calculated based on estimated initial population sizes, was the most profitable. The total net profit decreased as the number of fishermen in the higher class increased.