Effects of diets, sources and sizes of broodstock on ovarian development and spawning of giant tiger prawn (Penaeus monodon Fabricius)

Abstract

This study was carried out to determine the effects of diets, sources and sizes of broodstock on ovarian development and spawning of giant tiger prawn (Penaeus monodon Fabricius). The study was divided into two experiments. Experiment 1 comparatively studied the effects of broodstock sources, i.e. pond-rearded and shallow waters wild-caught p. monodon and different sizes, i.e. large size prawn (weight 120 g) and small size prawn (weight 110 g), on ovarian maturity and reproductive success. Experiment 2 studied the effect of the different diets on ovarian maturity and reproductive success of P. monodon. The three treatment diets were 1. fresh natural diets, 2. conbined diets (fresh natural diets plus artificial diet) and 3. artificial diet. The results showed that large female prawns could undergo' stage IV ovarian maturity and spawning better than the small ones. Both wild-caught and pond-reared females of the same size seemed to undergo comparable maturity and spawning success. The prawns fed with fresh natural diets and those fed with combined diets could undergo comparable stage IV ovarian maturity and spawning success, whereas, the prawns fed merely artificial diet underwent the least stage IV ovarian maturity and spawning. Large females could remature and spawn more frequently than the small ones. The prawns fed with natural diets and the prawns fed with conbined diets could remature and spawn more frequently than those fed with artificial diet. Diets, sources and sizes of broodstocks did not significantly affect the elapsed time between the eye-stalk ablation and the first stage IV ovarian maturity as well as the elapsed time between two consecutive stage IV ovarian maturities. The elapsed time between two consecutive stage IV ovarian maturities was significantly shorter than the elapsed time between the eye- stalk ablation and the first stage IV ovarian maturity. Diets, broodstock sources and sizes had no effect on the elapsed time between the eye-stalk ablation and the first spawning as well as the elapsed time between the two consecutive spawnings. The average number of eggs spawned per female of the large prawns was significantly greater than that of the small ones. The average number of eggs spawned per female of the prawns fed with natural diets was significantly greater than that of the prawns fed with artificial diet. Sources of broodstocks did not significantly affect the egg production of the prawns. Diets, sizes or sources of broodstocks did not produce significant effect on egg quality in terms of percent fertility, hatching rate and percent metamorphosis from eggs to the first protozoea stage. In addition, large ablated female prawns had a moulting period longer than the small ones.