Graduate School of Marine Biosciences, Tokyo University of Marine Science and Technology, Minato, Tokyo 108-8477, Japan
Genetic marking studies have recently been conducted in Japanese stock enhancement programs, mainly focusing on kuruma prawn Marsupenaeus japonicus, to evaluate the effectiveness of stocking. To obtain valid results it is important to understand the experimental design and statistical inference methods. This study overviews current genetic marking studies in world stock enhancement programs and considers practical issues for evaluating the effectiveness and impact of juvenile releases. Accurate DNA parentage assignment requires complete sampling of parents. For example, the resolution of parentage assignment in the kuruma prawn, for which paternal information is not available in most cases, is 50% at most. In such cases, genotyping of progenies or identification of the released offspring by external markers is indispensable to confirm the effectiveness of the genetic markers before conducting large-scale experiments. DNA parentage assignment, assignment methods and genetic stock identification are used to evaluate inter-generation effects of stocking. This review highlights the necessity of a basic understanding of experimental design and estimation methods in order to clarify the effectiveness of Japan's stock enhancement programs.