FISHERIES RESEARCH INSTITUTE,MOA,TAIWAN

A pair of 6-year-old red sea bream (Pagrus major) and two 4-year-old male were stocked in an indoor concrete tank with a dimension of 6×5×1.5 m. The spawning pattern and quality of eggs of the 6-year-old female was observed in this study. It has spawned 18 times during February 27 to March 26, 1992. Of which, the spawning in the two periods of February 27 to March 5 and March 12 to March 17 were happen daily, indicating that the red sea bream was multi-spawning species and would spawn daily. The total number of eggs spawned during the entire observed period was 8,878,100, and the maximum number of eggs spawned in a day was 898,000. Fertilization rates were ranged from 98.04% to 100% and hatching rates from 66.5% to 96.0%. The highest hatching rate was observed in the middle of spawning period. Productivity of eggs (fertilization rate×hatching rate×survival rate at the end of yolk sac period of hatched larvae) was also examined herein and the result showed that the highest productivity of eggs was happened during the middle period of the spawning (March 3 - March 12). Average diameters of spawned eggs ranged from 0.919 mm to 0.969 mm. A negative correlated relationship (r = -0.7746, n = 16) was observed between the average diameters of spawned eggs and the water temperature on the day before spawning. The growth of the broodstock during the period from January 3 to March 31 was suppressed completely and the average body weight decreased an 1.89%.