Comparison of ovarian maturation and spawning after unilateral eyestalk ablation of wild-caught and pond-reared Penaeus monodon

The present study compares the efficiency of ovarian maturation and spawning success between wild-caught and pond-reared Penaeus monodon females after unilateral eyestalk ablation. The earliest spawning time after eyestalk ablation was 5.9 days in wild-caught females, which is significantly shorter than the spawning time in pond-reared females (10.5 days). Both wild-caught and pond-reared females repeatedly spawned after eyestalk ablation. On average, each wild-caught female spawned 2.94 times while each pond-reared female spawned only 1.09 times. The spawning induction rate, egg hatching rate, and the number of eggs per spawning were significantly greater in wild-caught females than in pond-reared females. However, the egg size was not significantly different between wild-caught and pond-reared females. Four shrimp sizes (60, 80, 100 and 120 (± 1.0) g) were tested in this study and body weight significantly affected ovarian induction in pond-reared females but not in wild-caught females. Within the same body-weight class, the egg number per spawn in wild-caught females was significantly greater than that in pond-reared females. The egg production per spawn of the pond-reared females in the 120-g size group was two times higher than that in the pond-reared females in the 80-g size group. In conclusion, the fecundity of wild-caught P. monodon females is significantly higher than that of pond-reared P. monodon females. In breeding pond-reared P. monodon, the recommended minimum body weight of females is over 80 g, and the desirable body weight is over 100 g. (Author)