Quality of postlarvae and its improvement from multiple spawning of Penaeus monodon broodstocks | |
| Author | Hoang Tung |
| Call Number | AIT Thesis no. AS-98-04 |
| Subject(s) | Spawning Penaeus monodon |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Abstract | Intensification in using Penaeus monodon broodstocks and inappropriate pond management in nursery systems are believed to correlate with decline in quality of shrimp seeds in Khanh Hoa Province, Central Vietnam. Improvement in shrimp seed quality, therefore, is an urgent task. A research was conducted on changes in postlarval quality from multiple spawning of shrimp broodstocks. Its results can be considered as preliminary information about the relation between reusing broodstocks and quality of shrimp seeds. Results from the survey revealed that 94% of interviewed operators agreed that the quality of shrimp seeds decreased if shrimp broodstocks were reused. Broodstock fecundity, hatching rate, and survival of shrimp fry normally dropped from the 31 " to the 51 " spawn within an intermolt-spawning period (IP). Further experiments were conducted in cement tanks for 9 days to determine growth and survival of PLs from sequential spawns of individual shrimp broodstocks. Results showed clear declines in quality of the PLs from later spawns within an IP, and also from later IPs of shrimp broodstocks. Survival of the PLs from the 5th and 6th spawn were 46.4% and 0%, respectively, compared to that from the 1st and 3rd spawn of broodstock 1 (85.9% and 94.5%). Meanwhile, specific growth rate of the PLs from the 5 1 " spawn reduced to 10.9%/day, compared to 16.5-16.7%/day of PLs from the 1st and 3rd spawn. Similar results were observed with the PLs produced by another broodstock. However, the decline in postlarval quality started earlier at the 3rd spawn of the broodstock. An experiment was also conducted to improve PL growth and survival by green water rearing and supplementarily feeding with Artemia nauplii in initial 3 days. Results were variable depending on quality of the PLs (P<0.05). With high quality PLs, significantly higher specific growth rate (16 .4-19 .1 %/day) was observed in both treatments, compared to that in control treatment (14.4 %/day). Also, medium quality PL in fertilized tanks had superior survival (69.5%) in comparison to that in control unit (41.0%). Positive effect of supplementarily feeding with Artemia nauplii on shrimp growth was also observed. However, little treatment effect was found with low quality PLs, but susceptibility of reared PLs in control unit to 500-ppm formalin stress test was significantly higher at harvest. |
| Year | 1998 |
| Type | Thesis |
| School | School of Environment, Resources, and Development |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Agricultural and Aquatic Systems(AS) |
| Chairperson(s) | Lin, Chang Kwei; |
| Examination Committee(s) | Hambrey, John Bernard ;Y akupitiyage, Amararatne; |
| Scholarship Donor(s) | Keidaren Federation of Japanese Business Organizations; |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 1998 |