The design and management of tanks for the culture of turbot (Scophthalmus maximus (L.))
The culture of turbot Scophthalmus maximus is currently conducted only in tanks, unlike many pelagic species which are also grown in net cages. Despite the demersal habit of this species, deep pelagic fish tanks are often used with little or no adaptations. A multidisciplinary study was conducted to establish the consequences of several management regimes, primarily a decrease in water depth, on more than a total of 40 biological, water quality and hydrodynamic parameters. Fish fitness, performance and behaviour, exit age distribution, flow visualization, flow velocity determination and water quality determination studies were conducted. Results were discussed in relation to optimal tank management strategies, suitable tank designs, or adaptations to existing designs. A statistical model was proposed. A decrease in water depth from 18 - 9 cm decreased dead volumes from 6.95 - 1.37 1. An increase in depth from 3 - 18 cm increased turbot specific growth rate by 0.44 % day-1 . Tank hydrodynamics had little influence on biological or water quality parameters, despite the large range of water depths relative to the size of the tanks. It was more probable that stocking density and biomass were the major influences on water quality and this in turn may have influenced fish performance. The advantages of reducing water depth in a culture tank were more numerous than the disadvantages.