Estimation of Genetic Parameters for Hypoxia Tolerance in the Pacific Oyster, Crassostrea gigas

The Pacific oyster (Crassostrea gigas) is a primary shellfish species for aquaculture around the world. However, the industry of Pacific oyster has been impaired by the mass summer mortality caused by environmental perturbations, including hypoxia. Selective breeding of oysters with high hypoxia tolerance is a sustainable approach to prevent economic loss caused by hypoxia. In this study, we constructed 36 C. gigas families and executed the hypoxia stress experiment to estimate genetic parameters for hypoxia tolerance. The survival rate among 36 C. gigas families ranged from 0 to 53.33%, suggesting that high levels of phenotypic variation existed in the trait of hypoxia tolerance. Genetic parameters of hypoxia tolerance estimated by six statistical models showed a low to moderate heritability, ranging from 0.167 to 0.291. The Pearson and Spearman correlation coefficients among families estimated breeding values (EBVs) were high and positive, indicating that different models resulted in similar results in the estimation of breeding values. The phenotypic correlation between growth traits and hypoxia tolerance ranged from −0.030 to 0.061, while genetic correlation ranged from 0.110 to 0.285, implying that growth and hypoxia tolerance were independent traits. This work reported the first estimation of genetic parameters for hypoxia tolerance in C. gigas, and provided valuable information for the genetic improvement of hypoxia tolerance.