Figure 21. 



-Stack of trays containing salmon eggs being lowered into a deep-type 

 trough for the period of incubation. 



ally are mounted on horses or pedes- 

 tals about waist high. Occasionally 

 troughs may be placed on or in con- 

 crete tanks which later are used for 

 rearing. 



In some hatcheries the waste 

 water from the troughs may be 

 utilized in outside ponds. At the 

 Spring Creek (Wash.) Hatchery of 

 the Fish and Wildlife Service, it is 

 possible to drain the fish from the 

 troughs into the waste-water trough 

 in the floor and to divert known 

 numbers of these very small fish into 

 the various ponds for further rear- 

 ing, or directly to the fish ladder 

 down which they will descend to the 

 Columbia River and thence to the 

 ocean. 



Food preparation room. — At 

 salmon hatcheries the young fish are 



fed for different lengths of time be- 

 fore release. The diet received by 

 these fish is of major importance. 

 To prepare the foods properly for 

 presentation to the fish, a special 

 room and items of equipment are 

 required. The size of the room and 

 the size and variety of equipment 

 depend upon the quantities of food 

 to be prepared and the period of 

 t ime over which such quantities will 

 be required. A typical salmon- 

 liatchery feeding program starts 

 with the preparation of only a few 

 pounds of food for very small fish. 

 As the salmon grow, the quantities 

 of food required gradually increase 

 until a ton or more of prepared food 

 may be needed each day. 



A feeding operation of this mag- 

 nitude is accomplished in a food- 



44 



