1 RIGHT BANK ABUTMENT 



SPILLWAY 



t 



Figure 3. — Lower end of right ladder at different water 

 levels. Diagrammatic sketch shows photo areas: (a) 

 high flows; (b) intermediate flows; and (c) low flows. 



The estimating equation 

 is given by 



RJT a 



where 



T b = Number of tagged 

 dam 



for survival rate (k) 



fish released below 



R b = Number of tagged fish recovered from 



T, 

 T a = Number of tagged fish released above 



the dam 

 R„= Number of tagged fish recovered from 



T 



If the value of the ratio is one then mortality is 

 zero. Where the value of this ratio is less than 

 one, then the corresponding mortality rate is 

 given by \ — k. 



The results of tagging experiments on the 3- 

 year-old sockeye are shown in table 6. It is 

 apparent that too few 3-year-old sockeye were 

 tagged above the dam to afford meaningful com- 

 parisons between above and below dam experi- 

 ments and to give estimates of mortality rates. 

 No mortalities were evident from the limited data 

 available. A comparison of the recovery propor- 

 tions of tagged fish released below the left and 

 right fishways shows right bank releases having a 

 higher recovery rate in 2 of the 3 years. For all 

 years combined the two recovery rates were nearly 

 identical. 



346 



U.S. FISH AND WILDLIFE SERVICE 



