Biological Control through Aquaculture

The objective of aquaculture in the lakes is to biologically control aquatic weeds and plants with a view to improve the quality of lake water. Harvesting of fish has aims of indirect removal of nutrients from the lake, which is the cause of eutrophication. Aquaculture is an effective method for improving the water quality but it can’t be managed effectively without the co-operation of local fishermen. Hence as, a secondary objective it is envisaged that aquaculture will have a direct and positive impact on the economy with the increase in supply of fish as a food and upliftment of the living standards of fishermen. In the first phase, during 1997-99, about 26.70 lacs of Grass Carp, Common Carp, Catla, Rohu and Mrigal fish seeds have been stocked in Upper and Lower lakes. 12,000 tagged grass carps were released into the Upper and Lower lakes to monitor the growth of fishes, Regular monitoring of growth of fishes are being done through trial netting, assessment of fish catch by fishermen and market survey. These have revealed increasing trend of growth of fishes. Studies have also revealed that the density of weed has reduced substantially due to rearing of grass carp.

In the second phase during 2000-01, fish seeds of 7.66 lacs Grass carp and 2.89 lacs Indian Major Carps have been stocked in Upper lake. Scientific assessment of growth of fishes, then weed removal efficiency, heavy metal levels in fishes under normal as well as under pen culture condition are under way.