LAUSR

Abstract Interspecific hybridization has been used as an important tool for genetic manipulation in oyster culture with the aim to produce a new strains having desired traits from both the parental species. A two by two factorial cross between sympatric oyster species, Hong Kong oyster ( Crassostrea hongkongensis ) and Kumamoto oyster ( Crassostrea sikamea ), yielded hybrids that were fast growing (a characteristic of Hong Kong oyster) and had superior meat quality (characteristic to Kumamoto oyster). Reciprocal hybrids were obtained by the acceptable level of fertilization and hatching rate compared to these of two parental species. The survival rate of the hybrids was similar to that of the parental species. The hybrids exhibited fully developed gonads and gametes when sexually mature. Relative to C. sikamea , the hybrids also showed significant growth advantages as in shell height and wet weight. The shell morphology of the hybrid was dictated by maternal inheritance. Our results revealed that reciprocal hybrids exhibited larger growth heterosis and survival advantage (in terms of C. sikamea ), as well as a higher meat weight, showing great potential for application in the oyster aquaculture industry in southern China. Statement of relevance We firstly conducted the interspecific hybridization between the largest ( Crassostrea hongkongensis ) and smallest oysters ( C. sikamea ) in Crassostea genus, and then obtained reciprocal hybrids with obvious the heterosis (in terms of C. sikamea ). These hybrids are very useful as a new stock for the oyster aquaculture industry.