White Leg Prawn

Vannamei farmers continually seek to improve the efficiency of feeding methods in order to reduce operational costs and to minimise wasted feed settling on the bottom of the pond^{1, 2}. Waste feed, along with other organic discharges from farming operations, can potentially lead to pollution of receiving waters and adversely affect aquatic life through de-oxygenation and algal blooms which can be associated with nutrient increase. Organic matter can also be deposited and accumulate around discharge points. The key nutrients likely to cause problems for receiving water bodies are nitrogen and phosphorus³.

The type and quality of feed used will affect the discharge of nutrients. To improve their performance farms should monitor feed utilisation efficiency, the quality of the pond effluents and water quality in the receiving water body. Monitoring methods are documented within certification standards.

Farms should also document and record how they dispose of pond sludge and any other solid wastes. The use of sedimentation basins or dedicated ponds to capture particulates is effective but more work is required to remove dissolved nutrients⁴. One area of growing interest is the use of clean-up technologies such as constructed wetlands which allow plants to remove dissolved nutrients^{1, 5, 6, 7}. These plants can then be harvested giving the farmer an alternative income stream.