The evolution of aquaculture feed supply systems

Abstract

First paragraph: As any fish farmer knows, feed is usually the most important variable production cost. A simple objective is therefore to minimize waste from uneaten food, which has the added benefit of reducing the risk of environmental degradation. However, decreasing feed level risks reducing growth rate, leadìng to a rise in other costs per unit of production. The optimum biological feeding rate is thus rarely the same as the optimum economic rate. In practice, these calculations are complicated as feed requirement and efficiency of conversion varies with changing environmental conditions including water temperature, oxygen concentration, water quality, current speed, light intensity and day length. Feed utilisation also varies with diet quality and physiological factors such as age/size, life-stage, stress level and endogenous rhythms. lt is therefore not surprising that these factors contrìbute towards an element of uncertaìnty regarding the amount of feed required, often leading to under or over feeding of stock and resultant under performance of the system.