Thesis (M.Sc.) - Asian Institute of Technology, 2000

A thesis submitted in partial fu lfillment of the requirements for the degree of Master of Science, School of Environment, Resources and Development

Thesis (M. Sc.) - Asian Institute of Technology, 2000

The areas selected by the Department of Fisheries to collaborate with AIT Aquaculture Outreach Program to promote small-scale aquculture in 1997 and 1998 are located in Tramkok and Samrong districts, Takeo province. Aquaculture has been a minor subsistence activity of farm households and has been practiced by many farmers in order to get fish for home consumption or selling. This study is focused on the effect of AIT AARM Outreach Project recommendation on small-scale aquculture systems. Four groups of fish farmers were targeted in the study. Group one was respondents who worked with the AIT project since 1997 in Tramkok district, called Trialists 97, among whom 4 fish farmers discontinued fish culture in the next year. Group two was also respondents who worked with the project since 1998 in Samrong district, called Trialists 98, amongst whom 8 fish farmers has stopped fish farming. Group three and four were new entrants who do not work with the project and are called Nontrialists 98 in Tramkok and 99 in Samrong districts. Most ponds in the areas used for fish culture are rain-fed. Fish farmers tend to stock their ponds rather late, partly because of the late rains, but partly because of the inadequate seed supply. Late stocking leads to high risk of failure because survival rates of fish are reduced by the presence of predators in the fish pond. These predators migrate to the ponds from channels and swamps during and after heavy rains. Most farmers used organic manure rather than inorganic fertilizers due to their lack of capital and the fact that most owned some livestock. Average inputs of DAP and urea were 1.2 kgs and 1.6 kgs respectively per 100 m2 during a typical seven month culture period, while inputs of green manure and cow manure were 20.7 kgs and 35.2 kgs, respectively. Water quality was not as good. Some farmers in 1999 used too much fertilizers, which led to algal blooms, while others used much less. The levels of supplementary feed such as rice bran, duck weed and termites were lower than in the original trials. In particular, non-trialists were uncertain of the appropriate technical parameters for fish culture, although they had seen their fellow-trialist farmers. It is recommended that lime and fertilizers should be used for pond preparation, which had first, 10 to 20 kg per 100 m2 of lime to kill wild fish or predators; second, 5 to 10 kg per 100 m2 for making clear water in the pond and third 5 to 7 kg per 100 m2 to rectify acid soil of fishpond and to increase natural feeds in the pond. Five to ten days after spreading lime in the fishpond, fertilizers should be used to increase natural feeds in the fishpond. Normally, it is recommended to use 20 to 30 kg of cow manure, 15 to 20 kg of green manure and 1.5 to 3 kg per 100 m2 of inorganic fertilizers, urea and DAP (Diamonium phosphate), in a ratio of three parts of urea to one of DAP for every 100 m2 of pond. During fish culture period, it was recommended that inorganic fertilizer, urea and DAP, should be used at a rate of 0.4 - 0.5 kg per 100 m2 in the fish pond to make green water and organic fertilizer at about half the rate used in pond preparation. This means that fresh cow manure should be used at a rate of 10 to 15 kg per 100 m , and green manure at 7 to 10 kg per 100 m2 for applying into the fishpond in order to create plankton for fish feed. On the whole after two years of the project left from that area, many problems were found such as constraints of fish culture on improper technical use of fish farmers in pond preparation, wild fish, and management; fish stocking density; fertilizers use and fish seed