Fish Hatchery Management - fisheries & aquaculture

HATCHERY REqUIREMENTS 45galvanized sheet metal should be avoided. Dimensions of raceways vary,but generally a length:width:depth ratio of 30:3:l is popular. Properly constructedraceways have approximately identical water conditions from sideto side, with a gradual decline in dissolved oxygen from the head end tothe lower end. Levels of ammonia and any other metabolic waste productsgradually increase towards the lower end of the unit. Although thisrepresents a deterioration of water quality, some hatchery workers feel thata gradient in water quality might be better for the fish because it attractsthem to the higher quality water at the inflow end of the raceway. In circularponds, there is no opportunity for the fish to select higher oxygen andlower ammonia levels.FIGURE 19. Rectangular aluminum troughs (background) and concrete tanks.Small swim-up fry generally are started on feed in the troughs and thentransferred to the tanks when they are 1-lj-inch fingerlings. (fWS photo.)