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Abstract : |
An impact on nutrient loadings from cage culture of Nile tilapia, a freshwater fish, was carried out using sediment samples collected from the bottom of Prayeun District Reservoir, Khon Kaen Province, Northeast Thailand during October 1998 to September 1999. The water surface area of the reservoir was approximately 38.4 ha with water depth of approximately 6-8 m. Twenty cages (5x5x2.5 m) were used for Nile tilapia culture in the reservoir. The results showed that the amount of feeding stuff being used and the final fish production during the study period were 29,520 and 19,229 kg, respectively. The average feed conversion ratio over the studied period was 1.54. Organic matter, total nitrogen contents and available phosphorus of the bottom sediments of the reservoir under cage area, in most cases, tended to increase with time during the cage culture period. The percentages of organic matter contents in the sediments under cage sites and surrounding cage sites were at the range of 0.53-4.68 and 2.07-4.32, respectively. Total nitrogen contents in the sediments under cage sites and surrounding cage sites ranged from 0.03-0.25 % and 0.08-0.34 %, respectively. Available phosphorus in the sediments under cage sites and surroundine cage sites were 16.6-425 ppm and 43.6-82.8 ppm, respectively., |
