Nguyen Nhu Tri creator Lin, Chang Kwei Chairperson Edwards, Peter Examination Committee Hambrey, John B. Examination committee DANIDA, Denmark Scholarship donor text Bangkok Asian Institute of Technology 1998 continuing

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79 leaves The study was conducted to determine the environmental conditions and current culture system of clam ( Meretrix lyrata Sowerby) and blood cockle ( Anadara granosa Linnaeus) in Can Gio district, Ho chi Minh city, Viet Nam. In the district, the sandy and mudflat areas which can be used to culture clam and blood cockle are 1,3 86 and 717 hectares, respectively. In the past, clam and blood cockle were collected from nature by local people with very low productivity. Clam and blood cockle cultures have just been promoted recently. The present study was based on two farms for clam and three farms for blood cockle. Samples of clam, blood cockle, water and substrate of culture beds were collected and analyzed monthly to determine the growth rate in relation to environmental conditions at different selected farms. The results showed that growth rate of clam at two selected farms was not significantly different during the study, although the soil texture of these two farms was significantly different, especially in sand and silt composition ( P<0.01). Growth rate of blood cockle at three selected farms (A, B and C) was significantly different, especially between A and C, B and C. There was no significant difference in growth rate between A and B. The growth rate of blood cockle had a close relationship with clay and organic matter compositions in the culture beds. In economic term, very good return was gained from molluscs farming. Profits per hectare per year were 1,439 $US and 2,519 $US and profit margin were 59.8% and 40.8% for clam and blood cockle, respectively. Therefore, clam and blood cockle culture in Can Gio district should be promoted more in the future to improve the livelihood of local people. However, major constraints of the culture systems are shortage of seed, lack of technical knowledge and price fluctuation. They should be solved in a proper way to stimulate future development of clam and blood cockle culture in the district. A thesis submitted in pattial fulfillment of the requirements for the degree of . . Master of Science, School of Environment, Resources and Development Thesis (M.Sc.) - Asian Institute of Technology, 1998 Clam culture Vietnam Ho Chi Minh Asian Institute of Technology. http://203.159.5.9/ait-thesis/detail.php?q=B13105 http://203.159.5.9/ait-thesis/detail.php?q=B13105 20260818155715.0