Options to Reduce the Discharge of Wastes from Intensive Fish Culture

In contrast to fisheries, aquaculture has grown substantially in several regions of the world, and will continue to be a significant employer in food production. With the growth of the industry, pressures on the water resource system will increase, and protective mea­sures must be taken to permit its sustainable use. In modern aquaculture with carnivorous species, improved diet formulation leading to reduced nutrient output is one method of choice effectively employed in European and other industrialized countries, where efficient methods for effluent treatment in land-based fish culture systems have also been devel­oped. The use of recirculation systems will become more important for a number of appli­cations, especially for rearing juvenile fish for stocking. However, know-how on required system components and their interactions needs to be improved to tailor their application to species-specific requirements. Environmental regulations, their control and enforcement, is one issue of increasing worldwide importance. While in some countries aquaculture is over-regulated, the lack of enforcement in many tropical countries of even existing regu­lations is counterproductive to the needs of the industry itself. There is also room to im­prove cost-effective treatment methods for effluents for intensive fish culture systems. This paper deals mainly with experience gained under European conditions.