WAHLE and VREELAND: BIOECONOMIC CONTRIBUTION OF FALL CHINOOK SALMON 



'Special marks included. 

 ^Setnet and dip net fisheries. 



Southeastern Alaska 



33 7% 



20 



40 



60 



PERCENTAGE OF CATCH 



Figure 9.— Percentage of catch of 1961- to 1964-brood fall 

 Chinook salmon from 13 Columbia River study facilities taken by 

 area and fishery, 1963-69. Percentages do not add to 100% due to 

 rounding. 



timated by dividing the mark recoveries by the 

 appropriate special or common marked to un- 



marked relative survivals (see Contribution of 

 Hatchery Fish). 



Catch to escapement and survival estimates are 

 of limited value for several reasons. First, adjacent 

 tributary streams were surveyed during only 

 three of the seven return years of the study (1964- 

 66). Survey data are unavailable for at least one 

 return year for each brood. Thus, all catch to es- 

 capement ratios are probably overestimated and 

 survivals underestimated. Second, only a portion 

 of the fish returning to the streams could be 

 examined for marks. Total mark recoveries had to 

 be estimated from the survey samples. Third, in 

 some cases fish were delayed in entering adult 

 holding facilities and may have strayed to other 

 areas. Thus, some marked hatchery fish may not 

 have been counted. Fourth, use of average relative 

 survivals limited the accuracy of potential mark 

 catches and returns and thus the total survival 

 percentages. Relative survivals for individual 

 hatcheries could have differed greatly from the 

 averages. 



Catch to escapement ratios and total survivals 

 are needed to develop values for fisheries compen- 

 sation and enhancement projects related to water 

 use projects on the Columbia River system. Thus, 



199 



