Abstract
This paper estimates optimal production, fishing efforts, and stock of mackerel and jack mackerel caught by the large purse seine with current value Hamiltonian method and surplus production model. First of all, this study investigates volume of catches and fishing efforts of mackerel and jack mackerel caught by the large purse seine to estimate intrinsic growth rate, environmental carrying capacity, and catchability coefficient. Secondly, the study analyzes landing price and unit cost per fishing effort, and social discount rate to find optimal solution of production, fishing efforts, and stock by species from the current value Hamiltonian method. As a result, optimal production, fishing efforts, and stock summed from mackerel and jack mackerel caught by the large purse seine were 173,647 ton, 25,925 hauls, and 2,532,659 ton respectively. Optimal production, fishing efforts, and stock of mackerel caught by the large purse seine were 172,972 ton, 25,082 hauls, and 2,516,906 ton and optimal production, fishing efforts, and stock of jack mackerel were 702 ton, 843 hauls, and 15,753 ton respectively. In addition, when social discount rate continuously augments, the optimal production, fishing efforts, and stock of both species also increased. With increasing intrinsic growth rate of mackerel and jack mackerel, the optimal production, fishing efforts, and stock of them also increased. However, changing in the landing price and the cost per haul of both species, signals of the optimal production and stock of them were moved into opposite direction respectively. In conclusion, this study found that the large purse seine gears would catch much more mackerel with relatively high economic efficiency than jack mackerel under the optimal condition.