Feasibility exploration and comparative analysis of interspecific hybridization between Crassostrea hongkongensis and Crassostrea dianbaiensis

Interspecific hybridization plays a significant role in the genetic improvement of oysters in aquaculture, with the main objective being to obtain progeny that inherit the desirable traits of both parents and establish a stable inheritance pattern. Crassostrea hongkongensis is well-known for its large size and excellent meat quality. However, it exhibits poor resistance to external environmental changes and a high mortality rate. To address these shortcomings, this study conducted a 2 × 2 interspecific hybridization between Crassostrea dianbaiensis and C. hongkongensis. D larvae from C. hongkongensis ♀ × C. dianbaiensis ♂ (HD) and C. dianbaiensis ♀ × C. hongkongensis ♂ (DH) crosses were successfully hatched. However, the hatching index of both groups was lower than that of C. hongkongensis ♀ × C. hongkongensis ♂ (HH) and C. dianbaiensis ♀ × C. dianbaiensis ♂ (DD) groups. The average shell height of DH on the 15th day was only 111.50 ± 6.31 μm, and all individuals were dead by the 18th day. Despite experiments being repeated many times, no attached DH larvae were obtained. Compared with intraspecific hybridization, HD grew slower in the larval stage and had a lower survival rate, but the shell height of HD was slightly higher than that of HH on the 450th day (P > 0.05). The cumulative survival rate of HD throughout the growth period was higher than that of HH and DD, demonstrating a clear hybrid advantage in terms of relative yield and survival rate, especially higher than that of C. hongkongensis. Moreover, the gonads of HD can develop normally and produce gametes, and the color of the inner shell and body is between that of C. hongkongensis and C. dianbaiensis. These results indicate that HD effectively improved the survival rate of C. hongkongensis, demonstrating its great application potential and promising prospects in aquaculture.