Comparison of growth, survival and evaluation of genetic parameters in the rapid-growth strain of the orange shell Crassostrea gigas

The Pacific oyster, Crassostrea gigas, is a globally important aquaculture shellfish species. In recent years, it has faced challenges such as germplasm degradation and high mortality rates. Both China and international communities are actively working to cultivate new oyster varieties with superior growth performance and robust stress resistance. In this study, we constructed 11 half-sib families and 28 full-sib families using a nested design from rapid-growth strain of the orange shell C. gigas that had been mass-selected over three consecutive generations. Concurrently, wild individuals were used to establish control families to assess the growth and survival traits of the rapid-growth families of the orange shell C. gigas at different ages. The results indicated that during the larval stage, the growth and survival rates of the oyster families were higher than those of the control group, with average shell height and survival rates increasing by 12.40%–23.70% and 1.52%–13.98%, respectively. In the juvenile stage, compared with the control group, the shell height and survival rates of these families increased by 5.62%-10.74% and 2.34%-2.80%, respectively. However, further improvements in the survival rates of juvenile shellfish are needed. Significant differences were observed in growth and survival traits among different families (P<0.05), with families G14 and G23 showing greater advantages in growth and survival. Additionally, we evaluated the genetic parameters of shell height and shell length. The heritability of shell height and shell length ranged from (0.41±0.07) - (0.76±0.12) and (0.50±0.10) - (0.82±0.09), respectively, indicating medium and high heritability. The genetic and phenotypic correlations of shell height and shell length at different ages were positive, with correlation coefficients ranging from 0.95-0.99 and 0.28-0.75, respectively. This suggests that the growth traits of orange C. gigas have good breeding potential and can be selected indirectly. The fingdings of this study provided fundamental data for the development of the rapid-growth strain of the orange shell C. gigas.