Development of seed production techniques for grouper hybrids (Epinephelus coioides x Epinephelus lanceolatus) | |
| Author | Anocha Kiriyakit |
| Call Number | AIT Diss. no.AQ-11-03 |
| Subject(s) | Seed technology Groupers Epinephelus |
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctoral of Technical Science in Aquaculture and Aquatic Resources Management. |
| Publisher | Asian Institute of Technology |
| Abstract | Hybridization studies were carried out with the orange-spotted grouper, Epinephelus coioides and the giant grouper, Epinephelus lanceolatus. This study utilizes scarce milt from E. lanceolatus and year-round spawning of E. coioides making it easier to produce larvae for the purpose of enhancing fry and fingerling production. The first of four experiments compared the cross between the E. coioides (O+) and E. lanceolatus (O>) and the control. Stripped eggs from a female orange-spotted grouper were divided into 2 parts; one was fertilized with pooled sperm of three male giant groupers and the other from three male orange-spotted groupers. After hatching, they were stored in indoor 200 L rectangular plastic tanks at 10 larvar 1-1 and reared for 45 days. Larvae were fed a combination of oyster trochophore and rotifers during the first feeding (12 days after hatching) and then given Artemia nauplii until 45-days. Three was no difference in fertilization and hatching between hybrid and non-hybrids (control), but percent deformity of the hybrids (47%) was significantly higher (P<0.05) than non-hybrids (21%). At first feeding, survival of the hybrids (22%) was lower than the orange-spotted grouper (51%). However, this difference was not significant at the end of 45 days. Larval development stages were also not different between hybrids and non-hybrids during the observation period. At 45 days after hatching, the external appearance of hybrid groupers began to exhibit similarities to that of juvenile giant groupers ( yellow color with 5-7 oblique black bars across lateral lines). Since the early feeding plays a crucial role in the success of grouper larvae survival, six feeding regimes were investigated in the second experiment to find the appropriate first-feeding regimes. Newly hatched larvae were stocked at 10 larvae 1-1 in twelve indoor 2001 rectangular plastic tanks for 15 days. Three kinds of live prey were tested in a variety of combinations: copepod (Acarta sp.), rotifers (Brachionus plicatilis) and oyster trochophores (Saccostrea commercialis). The density of live prey was maintained uniformly at 20 ind mL-1 in all treatments. All live prey was capable, to varying degrees, of mean survival of non-hybrid larvae. However, copepod nauplii alone could not support the survival of hybrid larvae. Survival and growth of hybrid larvae were better when their feeding started with oyster trochophore. The results of this study suggest that initiating first feeding exclusively with oyster trochophore for the periods day 1 feeding (F1) to 3 (F3) followed by a combination of screened rotifer and copepod nauplii from day 4 (F4) to 7 (F7) resulted in the highest survival and growth of hybrid grouper. There are more alternatives in suitability feeding for the orange-spotted grouper larvae; copepod nauplii solely for F1-F7 or oyster trochopore for F1-F3 and screened rotifer F1-F7 were better for larval survival. While, larvae fed with oyster trochopore for F1-F3 and copepod nauplii for F1-F7 were higher growth of larval. The third experiment investigated the influence of four salinity levels (25, 30, 35, and 40%) on the fertilization and hatching, larval abnormality, survival and growth for a period of 45 days. Fertilized eggs of both groups were buoyant at salinity of 25%. Highest fertilization rates of grouper hybrid (74%) and non-hybrid (80%) were achieved with salinities of 30-35% and 30%, respectively. Hatching of both groups were better using water salinity in a range of 30 to 40%, compared with 25%. The size of newly hatched larvae of both hybrid and non-hybrid did not differ significantly (P>0.05) among the treatments. However, there was higher (P< 0.05) percentage of deformed larvae in salinity higher than 35%. Survival and growth of all larvae reared at lower salinities 25% and 30% were better than those in 35%. All larvae in 40% salinity died. This suggests that higher salinity is important during the fertilization and hatching than the nursing period. Intra-cohort cannibalism has been a major impediment to grouper larvae culture. Information on culture conditions for the fry stages is required to achieve reliable mass production of fingerlings. The forth experiment was conducted to examine the combination effects of two conditions of water color (clear or brown water), three levels of stocking densities (0.5, 1 and 2 fish. L-1) and three feeding frequencies (once, twice and three times daily) on survival and growth of the orange-spotted grouper (E. coioides) fry. Fry at 45 days post hatch were randomly stocked into 28 L aquaria (n=55) connected to a recirculating system. Quality of water had an effect on survival and growth after 30 day smpling. Rearing of grouper fry in brown water resulted in significantly higher survival and growth than in clear water. Highest larval survival and growth was (P<0.05) achieved at a stocking density of 0.5 fish L-1. When the stocking density was increased, survival and growth rate tended to decrease. Survival and growth were not affected by feeding schemes. Overall, all of these results are expected to the development of seed production technology for grouper hybrids in particular and grouper aquaculture in general. |
| Year | 2011 |
| Type | Dissertation |
| 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) | Gallardo, Wenresti G.;Bart, Amrit N. |
| Examination Committee(s) | Athapol Noomhorm;Coloso, Relicardo M.; |
| Scholarship Donor(s) | RTG Fellowship; Rajamangala University of Technology (RMUT) |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 2010 |