Influence of ploidy, genetic and environment on production traits of the Pacific oyster Crassostrea gigas

Abstract

Pacific oysters, Crassostrea gigas, are one of the most widely farmed shellfish. To meet demand, the advantages of growth and increased sterility are currently being exploited in the commercial culture of triploid C. gigas. However, the extent of the triploid advantage can vary, environmental conditions and rearing methods. In the present study, the performance of diploid and triploid oysters was compared at two sites (Rongcheng and Rushan) to determine whether the triploidization would result in any advantage on production traits that could be utilized for aquaculture of this species. Triploid oysters were also produced using the wild broodstock and selected line to verify whether selectively bred oysters maintain their improved traits after triploidization. In this study, we found that the survival advantage of triploid is “site-dependent” and that Rongcheng's triploids did not exhibit significantly higher cumulative survival than diploids. Notably, incremental survival of triploid oysters was consistently higher than that of diploids during the second summer, which may be related to gonad development and spawning in diploids. At both sites, growth traits (shell height and individual weight) were always higher for triploids than in diploids in both the selected and control groups, which is strong evidence of a superior growth advantage for triploids. In addition, we found that the production performance (growth, survival and yield) of the selected group was consistently better than that of the control group (either diploid or triploid), suggesting that the superior traits of diploids can be converted to triploids through ploidy manipulation. Our results support the notion that yield can be further optimized by reducing mortality through a selective breeding program coupled with triploid production to increase growth rates. This study provides meaningful information on the potential of triploid C. gigas for oyster culture in northern China.