Response to selection for growth in the second generation of two shell color lines of the bay scallop Argopecten irradians

Abstract The bay scallop Argopecten irradians is one of the most commercially important aquaculture species in China. A. irradians with two different shell color (red and black) from cultured stocks in China were used to establish two mass-selected strains (red shell line and black shell line) for fast growth, and a positive response to selection for fast growth was observed in the first generations. To determine whether continuous progress can be achieved by selection for growth, we evaluated response to selection for the second generations of the two shell color lines. At grow-out stage, a genetic gain of 13.23%–15.71%, selection response of 1.62–1.71 and realized heritability of 0.43–0.45 for shell length were observed in the selective breeding strains after two generations of selection. The current response to selection for growth obtained in the second-generation selection strains suggests that a large amount of genetic variance still remains in the selected strains and there is a potential for sustained genetic improvement in growth-related traits in these strains through selective breeding. The results obtained in this study provides important information for future breeding programs for A. irradians.