イシダイとイシガキダイの人工交雑種

概要

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Experiments of artificial hybridization between Japanese parrot fish Oplegnathus fasciatus and spotted parrot fish Oplegnatus punctatus, and of breeding the hybrids of both reciprocal crosses were carried out at Shirahama Fisheries Laboratory, Kinki University, in Wakayama Prefecture from 1969 to 1984. The eggs were obtained from mature fish reared in net cages at Shirahama, fertilized by the dry method and hatched 30 to 35 h after fertilization at a water temperature ranging from 22.0°C to 23.0°C. The rates of normal larvae obtained from the fertilized eggs were 78.8 to 89.9%. The long-term feeding experiments of F1 hybrid, Japanese parrot fish and spotted parrot fish, were carried out to compare the growth and survival rate, respectively. The larvae of F1 hybrid be-tween female Japanese parrot fish and male spotted parrot fish grew faster to market size than Japanese parrot fish.Survival rates of both reciprocal hybrids were higher than Japanese parrot fish and spotted parrot fish. Survival rates of both reciprocal hybrids were higher than Japanese parrot fish and spotted parrot fish. The morphological features of the F1 hybrid, in general, were an intermediate with wide variety between the parental species. Almost all F1 hybrid between female Japanese parrot fish and male spotted parrot fish matured three years after hatching, and more than 95% of the hybrids were female.