1996 Volume 44 Issue 2 Pages 151-157
Spawning of amberjack Seriola dumerili was observed using wild and hatchery broodstock fish reared at Tokyo Metropolitan Ogasawara Fisheries Center in 1990, 1991, and 1993. No artificial treatments such as hormonal injection or water temperature shock were required for induction of maturation and spawning. The number of broodstock fish was different every year, and varied from 11 to 46. The size of the fish ranged 63.7-97.6cm in fork length, and 4.7-16.5kg in body weight. Most spawnings occurred in May and June, and the total amount of eggs taken in 1990, 1991, and 1993 were approximately 54 millions. Throughout the spawning season, the water temperature varied between 21.2°C and 25.9°C. Optimum water temperature for spawning was estimated to be between 21.5°C and 23.5°C. The average rate of floating eggs and hatching rate were 78.4±24.44% and 84.0±21.90%, respectively. The average diameter of the egg was 1.10mm, and it ranged from 0.998 to 1.199mm. The average diameter of the oil globule was 0.27mm.
