Fish Hatchery Management - fisheries & aquaculture

FISH HATCHERYMANAGEMENTlllr,la::i; il;:FIGURE 20. Rectangular circulation rearing pond ("Burrows pond"). Water isrecirculated around the pond with the aid of turning vanes (arrow). waste waterflows out through floor drains located in the center wall (not shown). (FWSphoto.)Raceways should not vary in width, since any deviation can cause eddiesand result in accumulation of waste materials. It is desirable to have approximatelyone square foot of screen area at the outflow of the racewayfor each 25 gallons per minute water flow. The percent open area of thescreen material must also be considered.Raceways have some disadvantages. A substantial supply of water isrequired and young fish tend to accumulate at the inflow end of the unit,not utilizing the space efficiently. The raceway is believed by manyhatchery operators to be the best suited for mass-producing salmon fingerlings.Its ease of cleaning, feeding, and fish handling make it desirablewhere ample water supplies are available.RECTANGULAR CIRCULATION REARING PONDThe rectangular circulation rearing pond is commonly known as the"Burrow's Pond" (Figure 20).Its basic design incorporates a center wall partly dividing a rectangularpond into two sections of equal width. Water is introduced into the pondunder pressure and at relatively high velocities, through two inflow pipeslocated at opposite ends of the pond. The flow pattern is controlled with