Aquaculture potential of two Kumamoto oyster (Crassostrea sikamea) populations and their reciprocal hybrids in southern China

Abstract The Kumamoto oyster, Crassostrea sikamea, is a potential aquaculture species with a unique shape and delicious taste. It is naturally distributed along the coasts of East Asia, but it was inadvertently introduced into America from Japan, and has formed several geographic populations. In order to evaluate the aquaculture potential of C. sikamea hybrids, a complete diallel cross between two geographical populations (China and America) was conducted by using mixing gametes at an experimental station in Zhanjiang, Guangdong Province in southern China. Two intra-population mating groups (CC and AA) and two reciprocal inter-population crosses (CA and AC) were produced in triplicates. High fertilization rate and hatching rate were observed in all experimental groups, suggesting that there was no sperm-egg recognition barrier between these two geographic populations. Throughout the life cycle, the survival rate of reciprocal hybrids was higher than that of pure breeds. The heterosis in growth of whole weight of reciprocal hybrids in adulthood was significant, which was mainly influenced by mating strategy. In view of the performance difference between the progenies of the two pure populations, the aquaculture potential of the progenies of the American C. sikamea population was higher than that of the progenies of the Chinese indigenous population. The results demonstrated that the crossbreeding between Chinese and American C. sikamea populations can produce considerable heterosis, which can improve the C. sikamea aquaculture industry in southern China.