Pond-reared Penaeus Monodon Research Articles

Evaluation of Reproductive Capacity in Pond-Reared Penaeus monodon after Unilateral Eyestalk Ablation

Evaluation of Reproductive Capacity in Pond-Reared Penaeus monodon after Unilateral Eyestalk Ablation

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.

Reproductive behavioural differences between wild-caught and pond-reared Penaeus monodon prawn broodstock

Ongoing problems exist with the commercial scale domestication of Penaeus monodon. One of the major issues, in terms of reproductive performance, is the low egg hatch rate of eggs from these captive bred prawns. The current study investigated the related issue of mating success. Time lapse video observations were conducted to compare the mating behaviour of pond-reared (domesticated) and wild-caught prawn P. monodon broodstock.Mating success of the pond-reared prawns was found to be low relative to wild-caught. It was determined that both male and female prawns contributed to this low mating rate suggesting both genders were impacted negatively by the domestication process. The causative factors for the low mating success are yet to be determined, however external physical abnormalities and lack of sexual maturity did not appear to play a role. The most notable behavioural difference between wild-caught and domesticated prawns was a reduced level of pursuit behaviour by domesticated males. This and other behavioural differences are discussed in relation to an increasing body of evidence that male prawns respond to sex pheromones produced by receptive females and that males detect these chemical signals in part, via their second antennal flagella. Accordingly we hypothesise that pond-reared (domesticated) females may have a reduced ability to produce or release sex pheromones and males, a reduced ability to detect them when compared to their wild-caught counterparts.

The growth,development and sexual maturity of pond-reared Penaeus monodon

The growth,development and sexual maturity of pond-reared Penaeus monodon

Effects of Eyestalk Ablation on Maturation, Spawning, Hatching, Molting and Growth of Precocious Pond Reared Penaeus monodon

Effects of Eyestalk Ablation on Maturation, Spawning, Hatching, Molting and Growth of Precocious Pond Reared Penaeus monodon

Interrelationship between Maturation/Spawning Cycle and Molting Cycle of the Pond-reared Penaeus monodon

Interrelationship between Maturation/Spawning Cycle and Molting Cycle of the Pond-reared Penaeus monodon

Weight and time of onset of female-superior sexual dimorphism in pond reared Penaeus monodon

Crustacean females typically grow faster and achieve a larger size than males of the same age. This has implications for aquaculture of such species. Sexual dimorphism may warrant separating males and females during culture to ensure consistent harvest size shrimp from a pond, or in extreme cases mono-sex culture may be justified. We conducted an experiment to study the sex specific growth pattern of Peneaus monodon to determine extent of sexual dimorphism in growth and onset of sexual dimorphism. Shrimp were communally reared in two earthen ponds. One pond was for broodstock development at a low stocking density (7/m 2) and the other was stocked at a commercial stocking density (9/m 2). In the broodstock pond, females grew faster than the males after 70 days of culture and consistently maintained an average female-superior difference of 6-10 g. In the commercial pond onset of sexual dimorphism was at 90 days of culture, after which females grew faster than the males. In both pond types, the weight of shrimp at the onset of sexual dimorphism was similar, at 15-20 g. Therefore we conclude that weight is more important than age in determining onset of sexual dimorphism for growth in P. monodon. Females were approximately 8 g heavier than males in both ponds after 169 days of culture, so sexual dimorphism will be a major contributor to variation in harvest size if males and females are not reared separately.

Effects of dietary highly unsaturated fatty acids and astaxanthin on the fecundity and lipid content of pond-reared Penaeus monodon (Fabricius) broodstock

Five diets that contained fresh squid meat as the basic constituent and were supplemented with different amounts of highly unsaturated fatty acids (HUFA) and astaxanthin were fed to pond-reared Penaeus monodon broodstock. Diet A was sole squid meat. Diets B and C were supplemented with astaxanthin 50 and 100 mg kg−1 respectively. Diets D and E were supplemented with HUFA 5 and 10 g kg−1 and astaxanthin 50 mg kg−1 respectively. The result showed that the group fed diet E had the best reproductive performance in all experimental groups. It had a higher proportion of spawns (71.5%), spawning rate (0.047), a shorter latency period (7.7±0.3 d), higher absolute fecundity (× 103) (361.6±5.5) and egg production/female (× 103) (597.0±18.0) than all the other experimental groups. The fatty acid composition in broodstock diets strongly affected the tissue and fecundity of broodstock. Good correlations between the content of 20:4n-6 in eggs and the fecundity (r2=0.6109) and egg production (r2=0.9876) of broodstock were found. On the other hand, 22:6n-3 and DHA/EPA ratio was negatively correlated with the fecundity of broodstock (r2=0.5362, 0.8702 respectively). The result also showed that the balance between n-3 and n-6 fatty acid families, total polyunsaturated fatty acids and total saturated fatty acid and 20:5n-3 (EPA) and 22:6n-3 (DHA) may play vital roles in maturation and reproductive performance of P. monodon broodstock.

Bacterial flora in the hepatopancreas of pond-reared Penaeus monodon juveniles with luminous vibriosis

Quantification and characterization of bacterial flora in the hepatopancreas (hp) of pond-reared Penaeus monodon juveniles affected with luminous bacteria were conducted in 1994 and 1995. Shrimp samples were taken from 23 grow-out ponds, 14 of which had disease outbreaks. Luminous bacterial (LB) load of the shrimps' hp with (mean=2.4×10 1 colony forming units (CFU)/hp) and without (mean=0.3×10 1 CFU/hp) disease outbreaks were comparable during the first 15 days of culture (DOC). During disease outbreaks at 18 to 32 DOC, however, LB load of affected shrimps (mean=9.0×10 4 CFU/hp) were higher than healthy shrimps (mean=7.0×10 1 CFU/hp). At 50 to 60 DOC, levels of LB were comparable in older shrimps with or without disease. Total viable and presumptive Vibrio counts were also comparable in both shrimp samples from 1 to 60 DOC. Characterization of the 172 bacterial isolates collected showed that most (90.12%) were Vibrio species dominated by V. harveyi (27.91%), V. splendidus II (13.37%) and V. parahaemolyticus (10.46%).

Effects of different feeding regimes on ovarian maturation and spawning of pond-reared giant tiger prawn in Thailand

Large pond-reared Penaeus monodon were used in three maturation and spawning trials lasting 60 days. One group of prawns was fed a fresh diet only; a second group was supplied a fresh diet combined with a formulated pelleted diet; a third group of prawns received the formulated diet only. Total maturation (N = 66 and 55) and spawning events (N = 63 and 48) were much greater for prawns receiving only the fresh diet, and the combined fresh with formulated diets, respectively. Prawns receiving only the formulated diet matured only 12 times, and spawned 11 times. Prawns fed a fresh diet produced significantly more eggs than those given a formulated diet alone. No significant differences were seen in eggs produced per spawning event, % fertilization, % hatch or % metamorphosis from egg to protozoea. Female prawns exhibited greater mortality than did males, while females on the fresh diet only had greater mortality than did other females, presumably due to greater handling and other stress factors. Female prawns on a combined diet had lower mortality than other females. The formulated diet used is suitable for supplementation, but not as a sole maturation food.

Effects of eyestalk ablation, thoracic ganglion extract and gonad extract from 'spent spawners’on ovarian maturation in pond-reared shrimps, Penaeus monodon Fabricius

Abstract. Eyestalk-ablated and non-ablated pond-reared Penaeus monodon Fabricius of two sizes (116·3 ± 2·8g and 67·9 ± 1·0g body weight (BW)) were injected with crude thoracic ganglion extract from 'spent spawners’(0·4mg/g and 1·0mg/g shrimp respectively). Controls (ablated and non-ablated groups) received either equivalent amounts of crude muscle extract or crustacean saline. In another experiment, non-ablatéd shrimps (67·4 ± 1·8g BW) were injected with crude gonad extract from 'spent spawners'. The controls received an equal volume of crustacean saline. Significant differences (P < 0·05) in the gonadosomatic index and the gonad index in relation to the carapace length were detected between eyestalk-ablated and non-ablated shrimps; the larger shrimps showing a greater difference following treatments with muscle and thoracic ganglion extracts. However, no significant differences (P > 0·05) were detected between the thoracic ganglion-treated groups and the controls in either the eyestalk-ablated or non-ablated shrimps. Nor were significant differences (P > 0·05) observed between the gonad-treated group and the control and between the two control groups receiving crustacean saline and crude muscle extract.

Effects of unilateral eyestalk ablation on ovarian histology and oocyte size frequency of wild and pond-reared Penaeus monodon (Fabricius) broodstock

Effects of eyestalk ablation on ovarian maturation of wild and pond-reared Penaeus monodon were determined to compare their reproductive potential. This was done by counting the oocyte size frequency in four regions of the ovary and comparing the percentage of each cell type present at each stage of maturation per group. Sampling of ablated prawns was done during three maturation or spawning periods within the first molt cycle after ablation. It took 5 and 14 days for wild and pondreared prawns, respectively, to show signs of ovarian maturation after ablation. Percentage of proliferating cells, the smallest germinal cells in the prawn ovary, was higher in wild unablated (8.3%) than ablated (2.5–5.0%) groups. Significant differences were observed in all cell types at different stages of maturation. In both unablated and ablated prawns, there was a uniform development of the whole ovary and similar occurrence of atresia at all stages. The presence of bigger oocytes in the ovaries of ablated prawns sampled after spawning provided histological evidence for lower number of eggs per spawn and faster rematuration.

Effect of Fatty Acid Composition of Broodstock Diet on Tissue Fatty Acid Patterns and Egg Fertilization and Hatching in Pond-Reared Penaeus monodon

The effect of dietary fatty acid composition on tissue fatty acid patterns and spawn quality of pond-raised Penaeus monodon was evaluated with the use of three practical diets. Diets were formulated to contain the same basal components but with various lipid supplementation: Diet B1, 6% cod liver oil; Diet B2, 3% cod liver oil and 3% soybean lecithin; and Diet Ba, 691, soybean lecithin. Three flow-through maturation tanks were each stocked with 60 broodstock at a . sex ratio of 1.5 female to 1 male, with the females ablated on one eyestalk. Broodstock performance measured as total number and nature of spawnings, egg fertility and average hatching rate of eggs of each dietary treatment was assessed. Results showed that the fatty acid composition of broodstock diet affected the tissue fatty acid patterns and hatchability of eggs from pond-reared P. monodon. Females fed a diet high in 20:4n-6, 20:5n-3 and 22:6n-3 polyunsaturated fatty acids (PUFA) and n-3/n-6 fatty acid ratio gave higher percentages of fertilized eggs and higher hatching rates than did other diets.