Technical and economic consequences of increasing fish growth through the use of waste heat in aquaculture

Abstract

The effects of water temperature on fish feeding, metabolism and growth are examined with special reference to the common carp (Cyprinus carpio L). The effects of variations in temperature and ration level on the technical and economic characteristics of a simplified fish farming system are then established, and optimum levels for these parameters determined for a range of conditions using a computer model. The main advantage of increasing the farm temperature is a reduction in feed costs as a result of improved food conversion efficiency. Such a saving is however only valid for within species comparisons. Increased temperature also leads to a considerable reduction in holding costs, although the effect on total unit cost is not dramatic because of the relative insignificance of holding costs in the overall operating costs. Increased temperature has relatively little effect on water requirements/ costs per unit of production. The many extra costs and problems likely to be associated with the use of heated effluents are discussed. It is concluded that though heated effluents may be of use in culturing hardy fish or shellfish species with a high market value, it holds little promise as a means of producing large quantities of cheap fish for the mass market.