Harvesting selectivity and stochastic recruitment in economic models of age-structured fisheries
构建了包含内生的捕捞选择性和随机补充的年龄结构渔业模型，发现最大可持续产量（MSY）因忽略捕捞成本对渔具选择性的依赖而严重偏离经济最优，并用波罗的海鳕鱼数据量化了这种差异。
We develop the age-structured fishery model by including endogenous harvesting selectivity and stochastic recruitment, as a growing body of fishery ecological evidence suggests these factors to be critical for fisheries management. Optimal harvesting selectivity aims to direct fishing towards age classes that are preferable to catch given information on fish growth, natural mortality, and recruitment in addition to implications on harvesting cost. We analytically show that maximum sustainable yield (MSY) leads to potentially serious and previously unrecognized deviation from economic optimality, as it neglects the dependence of harvesting costs on gear selectivity. We further show that the steady-state population level may fall below the MSY population even with zero discounting and stock-dependent harvesting costs. We quantify our results using empirical data for Baltic cod. Applying the age-structured model with endogenous harvesting selectivity, we find large differences between maximum sustainable yield and the economic optimum, although the classic biomass model suggests that these differences should be unimportant. Stochastic recruitment implies a threefold increase in young age classes, but the stochastic solution can be accurately approximated by the certainty equivalence principle.