I'iGUKK 2G.— Seining chum salmon from the holding area at the Walcott Slough, 

 Wash., spawning station of the Fish and Wildlife Service. Entrance V at lower 

 right. --■^M^'^^^ik 



either trapping or diverting the 

 sahnon to holding ponds will de- 

 pend upon the character of the 

 stream and upon the species of fish 

 to be spaAvned. Also dependent 

 upon these factors will be the deter- 

 mination whether fish will be 

 trapped in the stream or diverted 

 to holding and spawning ponds. 

 The latter is most convenient and 

 successful for sjoawning operations 

 at a hatchery where water supplies 

 are readily available for the ponds. 

 In isolated areas or at points re- 

 moved from the hatchery, a tempo- 

 rary installation for trapping and 

 spawning directly in the stream is 

 most economical. 



Adult Holding Ponds 



Holding or retaining ponds for 

 adult salmon differ greatly in size, 

 depth, and general features. The 

 principal differences are found in 

 ponds designed for receiving and 

 holding fall chinook salmon and 

 those for spring chinooks. The 

 spring chinook is more vigorous and 

 aggressive in attempting to leave 

 the pond and move further up- 

 stream. He also must be held much 

 longer before maturing than the fall 

 fish. 



The retaining ponds for spring 

 chinook salmon are quite compli- 

 cated and are carefully designed 

 and constructed to avoid death of 



51 



