Fertilization, survival and growth of hybrids between Crassostrea gigas and Crassostrea sikamea

Crossbreeding is a powerful tool for animal breeding and genetic improvement in aquaculture. In this work, artificial interspecific hybridization was carried out and three crosses were successfully produced, namely Crassostrea gigas (GG), C. sikamea (SS) and C. sikamea female x C. gigas male (SG), although C. gigas female x C. sikamea male formed nonviable hybrid offspring. The fertilization and hatching success of the SG cross was at an acceptable level compared with that of the intraspecific crosses. At the larval stage, the growth rate of the SG cross corresponded to that of the SS cross, but was significantly lower than the GG cross, and the survival rate of the SG cross did not differ from that of either parental cross. During the spat stage, the single-parent heterosis value of the growth rate for the SG cross ranged from 8.85 to 24.43%. Considering survival rates, notable mid-parent heterosis (27.16-76.00%) and clear single-parent heterosis (30.53-73.28%) were observed, though no significant differences were observed among the three crosses. Our results clearly demonstrate that the production performance of the hybrid SG cross is comparable to that of the maternal parental SS cross. The high survival advantage and single-parent heterosis for the growth trait observed in the SG cross provides a promising method for the genetic improvement of oysters.