FISHERIES RESEARCH INSTITUTE,MOA,TAIWAN

Eight batches of mature prawns, Penaeus monodon, were collected from grouper ponds. In one of the batches, there was 14 female with ovarian index of 2.4±0.9. Two of them spawned naturally on the third and the sixth day, and hatched 728,000, and 119,000 nauplii, respectively. Another batch has 25 females with ovarian index of 2.0±0.8. Those females started to spawn from 3 to11 days after uni-eyestalk was ablated. The average number of eggs was 238,000±122,000 with fertilization rate of 90.7±6.8% and hatching rate of 90.5±2.1%. Most of females spawned more than twice, one of them spawned four times. The most productive female laid 1,090,000 eggs and hatched 565,000 nauplii. Study suggested that high fecundity of pond-reared tiger prawn was due to: (1) low culture density in pond that allowed them to have a fast growth; (2) sufficient and highly nutritious food; (3) well environmental conditions that was similar to open sea, and (4) long culture period 10~12 month for fully growth, reaching size greater than 120 g.