and upon the looseness and position 

 of the eggs as determined by gently 

 passing the hand over the abdomen. 

 Picking the fish up and gently 

 pressing on the abdomen will result 

 in the extrusion of eggs from the 

 vent, but this method is not always 

 indicative of the maturity of all 

 eggs, as those near the vent may be 

 ready for spawning while others 

 further forward may not have sepa- 

 rated. Under natural conditions, 

 spawning by each female is under 

 way for several days, the eggs being 

 released as they become mature. It 

 is impractical in artificial spawning 

 operations to extend the spawning 

 of each fish over several days, so 

 quite often the spawning of appar- 

 ently ripe females is delayed for an 

 additional day in order to be certain 

 that all eggs are separated, which 

 results in improved fertilization of 



eggs. However, where large num- 

 bers of adults are handled, as at 

 some of the lower Columbia River 

 stations, space does not permit this 

 practice. 



Usually all males attending the 

 females are ripe and will produce 

 adequate sperm. Only 1 male is 

 considered necessary for the fertili- 

 zation of the eggs of 3 or 4 females 

 when artificially spawned. As the 

 sexes appear in approximately equal 

 numbers the surplus males usually 

 are removed, j^articularly when 

 large numbers of fish must be han- 

 dled and space is at a premium. In 

 the event that there is a shortage of 

 males, those present are utilized sev- 

 eral times, as they create new sperm 

 to replace that taken. 



When the sorting of fish is com- 

 pleted and all ripe females and a 



FitiUKK 11 



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