2018 年 24 巻 1 号 p. 1-8
Release of artificially hatched juveniles of P. altivelis into river systems has been a common solution strategy to maintain their population. In addition, each inland fishery cooperatives in Japan is required to release fishes into the block in rivers that they manage; a block is a set of several fishing sites with the same river environment. The release should be carried out considering characteristics of blocks in a river system, so that a performance index is maximized, which consists of the utilities of blocks that increases as the total number of the allocated fish increases and the penalty that restrains difference in the allocated fish between the blocks. However, such an approach has not been addressed so far. In this paper, to tackle this problem, an optimal allocation model to determine the allocation of the released fish into several blocks in a river system is proposed. The decision-makers in the model is a fishery cooperatives which manage blocks in the river system. Here, an optimal allocation policy can be obtained by solving a constrained nonlinear and static optimization problem and is numerically computed with a logarithmic barrier function method focusing on the particular case of Hii River, Japan.