451 



401 



5 



o 



351 



E 30 



o 



< 

 o 



X 

 CO 



251 



20L 



15 



CO 

 Q 



101 



o 



Q. 







HATCHERY OPERATIONS 65 



co: 



^^: 



5g. lOg. 



91/lb 45/lb 



FISH SIZE 



15g. 

 30/lb 



Figure 25. Carrying capacity of oxygen- saturated water 

 at normal activity level of fingerling chinook salmon as 

 affected by water temperature and fish size. (Source: Bur- 

 rows and Combs 1968.) 



Catastrophic fish losses because of overloaded rearing facilities are an 

 ever-present danger in fish hatcheries. Many successful managers have 

 operated a fish hatchery as an art, making judgements by intuition and ex- 

 perience. However, there are several quantitative approaches for estimating 

 carrying capacities in fish hatcheries. 



Experience has shown that fish density can be increased as fish increase 

 in size. Figure 24 demonstrates the increase in density that is possible with 

 chinook salmon. The carrying capacity of oxygen-saturated water at five 

 water temperatures and several sizes of chinook salmon fingerlings is 

 presented in Figure 25. Oxygen is usually the limiting factor at warmer 



