ENVIRONMENTAL AND ECONOMIC EVALUATION OF TILAPIA FISH CAGES IN NILE RIVER, DAMIETTA BRANCH AND THEIR EFFECTS ON NILE WATER RESOURCES

Egyptian fish production from aquaculture in fresh and brackish water contributed 59% of total Egyptian fish production. Due to the limited availability of protected sites and the conflicts of aquaculture activities, floating cages of Tilapia fish culture have been established since 1988 along Nile River, Damietta and Rasheed branches. Three thousands and two hundred floating Tilapia fish cages were constructed in area about two kilometers along the Nile river, Damietta branch facing Adlya ,Kafre Saad , and Faraskour villages, for rearing of 20,000 Tilapia fish per cage (10ҳ 10 ҳ 6m ). In the floating net cages, the fingerlings of Tilapia (monosex Oreochromis niloticus) were cultured for six months and up to one year at densities of 30 and 60 fish per cubic meter , in semi-intensive and intensive culture respectively. Using of Nile water in cooling the boilers in Kafr Al-Batteekh electric station, Damietta Governorate, leading to rise water temperature of the river upstream of the area of Tilapia cages, encouraging fish culturing in floating cages downstream of that region of the river as well as increasing phytoplankton load. This study is to clarify the environmental impacts of wastes of fish feeds, antibiotics, hormones and fish operations, on raw water of the river, bottom biota and the quality of the drinking water taken from the river in Damietta Governorate. There is also a need to consider social and economic study of Tilapia cage culture operations in Egypt and seeking advices on how to manage and expand operations of fish culture, besides minimizing their adverse environmental impacts on Nile water.