BROODSTOCK, SPAWNING, AND EGG HANDLING 167 



Figure 57. Spawning of salmonids with air pressure. 



Urine-free sperm can be collected through a pipette inserted about 0.5 

 inch into the sperm duct. If the male trout is gently stripped by hand, suc- 

 tion on the pipette will draw clean sperm out of the fish. Sperm and eggs 

 are then mixed together. 



Factors Affecting Fertilization 



Several factors may have an adverse affect on fertilization during the 

 spawning process at a hatchery. The contamination of either eggs or sperm 

 can result in low levels of fertility. In the case of most salmonids, pro- 

 longed exposure of either sperm or eggs to water will reduce fertility. 

 Sperm mixed with water are highly active for up to 15 seconds; after that, 

 motility declines and usually no activity is recorded after 2 minutes. Eggs 

 rapidly begin absorption of water shortly after contact with it and may be- 

 come nonviable if they have not been fertilized. 



