| Author | Athitaya Chaiparinya |
| Call Number | AIT Thesis no.AE-96-16 |
| Subject(s) | Catfishes--Thailand
|
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science |
| Publisher | Asian Institute of Technology |
| Abstract | This thesis studied the current status of catfish in three regions of Thailand in wild, open and closed environment, their life habits and catfish identification in Thai native catfish Clarias macrocephalus, exotic African catfish C. gariepinus and and their hybrid catfish (C. macrocephalus x C. gariepinus) and genetic variation in C. macrocephalus and C. gariepinus. The actors interviewed were farmers, fishermen, catching teams, Trichogaster farm operators and hatchery operators in three provinces, Si Sa Ket, Samut Prakan and Nakhon Sawan. Fishermen and fish catching teams believe that native stocks of walking catfish are decreasing in Si Sa Ket and Nakhon Sawan and are stable in Samut Prakan. The African catfish and hybrid catfish (C. macrocephalus x C. gariepinus) is thought to be increasing in natural systems. An analysis of fishers practices revealed differences in techniques but macrophyte cover being an important characteristic of good fishing areas. The most commonly used criteria for catfish identification are body color, body pattern, occipital process, head and pectoral fin spine characteristics. Different actors indicated different abilities to identify fish and relied on different characteristics thus whilst all actors could identify Thai catfish, hatchery operators were more confident to recognize hybrids than fishermen or, particularly, farmers and fish catching teams. Also whereas hatchery operators and fishermen used mainly body color, body pattern and form of occipital process to identify Thai catfish, characteristic of the head and pectoral fin spines were used as frequently. Tissue samples from a total 420 of wild (C. macrocephalus) and hatchery (C. gariepinus) catfish stocks from six locations in three regions of Thailand were examined for genetic variation at nine enzyme loci. Average heterozygosity of C. macrocephalus and C. gariepinus ranged from 0.105 ± 0.052 to 0.166 ± 0.072 and 0.184 ± 0.073 to 0.274 ± 0.085. The allele frequencies were used to estimate Nei's unbiased distance (D) which ranged from 0.001 to 0.030 for C. macrocephalus and 0.009 to 0.058 for C. gariepinus. There were no significant differences in genetic variability in C. macrocephalus samples from different populations but samples of C. gariepinus from Rasisarai, there were significantly different from others (P< 0.01). It is possible that there has been introgression of C. macrocephalus into the hatchery C. gariepinus population in Si Sa Ket. This is indicated by the presence of C. macrocephalus alleles at the GPI-1 loci in C. gariepinus all the hatchery stocks samples in Si Sa Ket. |
| Year | 1996 |
| 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 | Agricultural and Food Engineering (AE) |
| Chairperson(s) | Little, David C.; |
| Examination Committee(s) | Lin, Chang Kwei;Hambrey, John;Mair, G.C.; |
| Scholarship Donor(s) | Royal Thai Government; |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 1996 |