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FISH HATCHERY MANAGEMENT 



Figure 36. Perforated aluminum screens showing (l) round holes, (2) staggered 

 slots, and (3) nonstaggered slots. (Courtesy California Department of Fish and 

 Game.) 



actually leak if the bottom is disturbed, and it may be necessary to com- 

 pact their bottom with a sheepsfoot roller, rather than to disk them. 



If a pond is to remain dry for several months it should be seeded around 

 the edges with rye grass (8-10 pounds per acre). This cover prevents ero- 

 sion of pond dikes and it can be flooded in the spring to serve as a source 

 of organic fertilizer. The grass should be cut and partially dried before the 

 pond is reflooded, or its rapid decay in water may deplete dissolved 

 oxygen. 



Application of 1,000 pounds per acre of agricultural lime during the fal- 

 lowing period, followed by disking, may improve the buffering capacity of 



