A MODEL OF GENE DISPLACEMENT BY STOCKING ACTIVITIES

Recent advances in aquatic hatcheries with a variety of fish and shell fish made a large scale stocking of artificially produced seeds into n atural fishing grounds possible. When the genetic properties of the st ocking population are different from the wild population, displacement of the gene in the wild population will gradually occur by the gene o f the stocking population through reproduction. In this study, we inve stigate the change of the composition of both genes, in terms of the r ate of stocking and fitness of the individuals of each genotype, using a simple mathematical model. When the fitness is equal in each genoty pe and the rate of stocking is 10%, the term that the gene of the wild becomes half (Genetic Halving Time, GHT) is 8 generations, and the te rm that the gene of the wild becomes 1% (Genetic Displacement Time, GD T) is 49 generations. When the fitness of the hybrid between wild and stocking individuals is smaller that both parents, GHT and GDT are muc h smaller.