46 



FISH HATCHERY MANAGEMENT 



Figure 20. Rectangular circulation rearing pond ("Burrows pond"). Water is 

 recirculated around the pond with the aid of turning vanes (arrow). Waste water 

 flows out through floor drains located in the center wall (not shown). (FWS 

 photo.) 



Raceways should not vary in width, since any deviation can cause eddies 

 and result in accumulation of waste materials. It is desirable to have ap- 

 proximately one square foot of screen area at the outflow of the raceway 

 for each 25 gallons per minute water flow. The percent open area of the 

 screen material must also be considered. 



Raceways have some disadvantages. A substantial supply of water is 

 required and young fish tend to accumulate at the inflow end of the unit, 

 not utilizing the space efficiently. The raceway is believed by many 

 hatchery operators to be the best suited for mass-producing salmon finger- 

 lings. Its ease of cleaning, feeding, and fish handling make it desirable 

 where ample water supplies are available. 



RECTANGULAR CIRCULATION REARING POND 



The rectangular circulation rearing pond is commonly known as the 

 "Burrow's Pond" (Figure 20). 



Its basic design incorporates a center wall partly dividing a rectangular 

 pond into two sections of equal width. Water is introduced into the pond 

 under pressure and at relatively high velocities, through two inflow pipes 

 located at opposite ends of the pond. The flow pattern is controlled with 



