Effects of salinity on the growth of Oreochromis niloticus, O. mossambicus and their hybrids | |
| Author | Kamal, Abu Hena Md. Mostofa |
| Call Number | AIT Thesis no.AQ-03-31 |
| Subject(s) | Nile tilapia -- Growth Mozambique tilapia -- Growth |
| 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 |
| Series Statement | Thesis ; no. AQ-03-31 |
| Abstract | An study was conducted to determine the relative salinity tolerance (determined through evaluation of growth and survival) of newly available superior strains of Oreochromis niloticus, 0. mossambicus and their hybrids. The study consisted of two parts: an on-station experiment and on-farm experiment. In the case of the on-station experiment, eight genotypes (two strains each of the pure species and the four hybrids produced from crosses between them) were cultured separately in one-m2 cage inside 4- metric ton concrete tanks at five different salinities namely 0, 7.5, 15, 22.5 and 30 ppt, for a period of 75 days. Fifteen fish were stocked in each cage and four cages were set in one tank. Fish were fed commercial floating pellet two times daily with rations prepared according to fish biomass per cage. In the on-farm trials, forty fish of each genotype were stocked communally in 16- m2 cages at three different sites in brackish water ponds and canals of the coastal area of Phechaburi. The different genotypes were marked using combinations of Coded Wire Tags (CWT) inserted in one of four locations and pelvic fin clips. The fish were on-grown, without feeding, for sixty-three days. The interpretation of the results of the tank-based experiment was confounded by significant differences in initial weight of the different genotypes at stocking which with a conesponding impact upon the feed administered. This may account for the considerably larger size throughout the experiment of one of the hybrid genotypes. As a result the interpretation of growth based on weight gain, differed somewhat from that using specific growth rate. All the genotypes showed better growth performance at elevated salinity ranging from 7.5 to 22.5 ppt than in fresh water. Among 0. niloticus, 0. mossambicus and their hybrids, the highest growth performance was found in the hybrids over a wide range of salinity. In pair wise comparisons 0. niloticus had superior growth to 0. mossambicus at all salinities although 0. niloticus suffered some disease at 30ppt with some associated mortality resulting in a lower biomass of 0. niloticus at harvest compared to 0. mossambicus at this salinity. The hybrid produced superior weight gain to 0. mossambicus in all treatment. 0. niloticus had superior weight gain to the hybrids only in freshwater, with the hybrid being superior at all salinities. In case of communal stocking of genotypes in on-farm trials in fluctuating salinity brackish water, the hybrid again showed better growth performance than the pure species. The highest growth of all genotypes was observed in the location with highest salinity. 0. niloticus produced relatively greater superiority of growth over 0. mossambicus in the farm trials than in the tank experiment Considering the results from the tank trials and farm trials together, it is apparent that the hybrid between these superior pure species stocks is the most suitable for brackish water tilapia culture although 0. niloticus remains the best choice for culture in freshwater. |
| Year | 2003 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. AQ-03-31 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Aquaculture and Aquatic Resources Management (AQ) |
| Chairperson(s) | Yakupitiyage, Amararatne; |
| Examination Committee(s) | Mair, Graham C. ;Yi, Yang; |
| Scholarship Donor(s) | D.F.l.D. (United Kingdom); |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 2003 |