6.5 GROWTH AND SURVIVAL

Assuming spat are being cultured at reasonable density, their growth rate is largely influenced by the quality of food given in terms of the nutritional value of the component species of the diet, the ration of food provided and water temperature. Other factors play a part, such as salinity and genetics, but their effects are relatively minor in comparison. The effects of the biomass of spat per unit volume of the system in which they are grown have already been discussed. A density of 200 g live weight per m3 of tank volume represents a good compromise between density for maximum growth, which occurs at below 25% of that biomass, and economic considerations such as the space needed to accommodate tanks and the volumes of heated, treated seawater required.