1Tamano Station, National Center for Stock Enhancement, Fisheries Research Agency, Tamano, Okayama 706- 0002, 2Faculty of Marine Science, Tokyo University of Marine Science and Technology, Minato, Tokyo 108- 8477, 3Yashima Station, National Center for Stock Enhancement, Fisheries Research Agency, Takamatsu, Kagawa 761- 0111, Japan
A simple population dynamics model that accounts for variation in natural recruitment was developed to simulate the effects of hatchery releases and fishing regulation on fishery resources. We applied this model to the stock recovery plan for Japanese Spanish mackerel Scomberomorus niphonius in the eastern Seto Inland Sea and evaluated the probabilities of various scenarios for achieving the goal of the stock recovery plan. For the scenario of no regulation with zero release, the success probability for achieving the goal was estimated at 63.4%. Conversely, for the scenario of prohibiting autumn fishing targeting 0-year-old mackerel with the release of 50,000 juveniles, the success probability was estimated at 99.3%. The model was also applied to scenarios of fisheries management based on ABC (Allowable Biological Catch) proposed by the Fisheries Agency of Japan, and stock sizes and catches until 2030 were predicted.