Reproductive performance of Macrobrachium rosenbergii females in captivity

The breeding frequency. fecundity, egg hatchability. larval output and viab ility of pond-reared, mature Macrobrachium rosenbergii females were individ ually followed up during 180 d. Sexually mature prawns were maintained unde r controlled laboratory conditions (28.7 C and 12-h light/d) in a 190-L fre shwater recirculation system and fed a formulated diet. Ovarian development . moulting and spawning events were checked daily. Ar least six consecutive moults were recorded for each of the 18 females. The duration of the inter moult period averaged 27.5 d and was not affected by ovarian development or spawning. but intermoult periods followed by spawning had significantly lo wer growth rates. From a total of 126 moulting events recorded, egg laying successfully followed 76 (60.3%) of them. The number of eggs per spawn (NES ) varied from 26.587 to 74.775 for females weighing 20.0 to 55.8 g. The rel ationship between NES and female size (W: in g) was found to be NES = 484 1454W (r(2) = 0.74). Results suggest that the number of viable larvae prod uced per egg clutch may he increased by in vitro incubation, as the losses of eggs. which usually occur under in vivo incubation, are prevented. The p resent study illustrates that under adequate and stable rearing conditions, M. rosenbergii females are able to spawn up to five times during 180 d. in comparison to three to five times per year as reported for wild prawn popu lations.