FEMALE SALMON (0. ncrlM) OF THE COLUMBIA RIVER 



433 



1957 



Okonogan (32's) N = 7 



Okonogon (4 2's) N =16 



Wenotchee (42's) '^ = 1'^ 



Wenotchee (Sjig) N= 6 



Both Rivers (42's) N= 33 



I I Range 



I I Stondord Deviation 



^i Mean a Standard error of mean 



mean minus stondard deviaticn = 2,271 

 lowest observed voiue =2,328 



nz 



D 



All samples 



from 

 commercial 

 cof ch 



1958 

 (32's) 

 (42's) 



(53's) 

 (52's) 



N= 9 

 N = 30 

 N = 7 

 N = 10 



□r 



nm 



1959 

 Rock Is. Dom (32's) ^- '0 



Comnierciol (4 ) ^ = 22 

 Catch ^ ^ 



Composite of All Years 



^2'S 



N = 26 



(42's) N = 85 

 (53's) N= 13 

 (52's) N = 13 



czn 



2C 



3 



_i_ 



NUMBER OF EGGS 1500 2000 2500 3000 3500 4000 4500 



Fic.uRE 2. — Fecundity statistics of the blueback .salmon ago group samples. 

 Table 4. — Fecundity statistics of the age-group samples of Columbia River blueback salmon 1957-59 



Tlie most striking feature is the within-year 

 (UfTcrenee in mean fecundity between age groups 

 witii different ocean age. The mean fecundity of 

 the 32's was lower tlian that of the 42's by 33, 

 26, and 32 percent for the years 1957, 1958, and 

 1959, in tiiat order. On a simihir basis we find 

 that the 1958 3-year-ocean females (52's) averaged 

 26 percent more eggs tiian the dominant 4; age 



group for that yeaf. The 3-year means of 

 fecundity were 2,014, 2,897, 2,801, and 3,609 for 

 the 32, 42, 53, and So age groups, respectively. 



Variations in tlie measuring techniques and in 

 the sampling sites cast sufficient doubt on the 

 validity of the fork-length data to preclude their 

 extensive use. For that reason we have limited 

 tlie analysis to comparison of age group means. 



