I- ^ 



IS 



o — 



I- 0. 



^ 3 



w o 



5 cr 



lij o 



HJ 2 



g° 



80- 

 70- 

 60- 

 50- 

 40 

 30 

 2 0- 



10- 

 0- 



80 

 70- 

 60- 

 50- 

 40 

 30 

 20- 

 10 

 0- 



2 FRESH-WATER 



3 FRESH-WATER 



25 30 



JUNE 



"I 1 



5 10 



JULY 



I * A ,\ 



\ I \ , \ M 



V i / i ' * / \ ' ' 



—^' I I * S J " \ 



\l v y i 



2 OCEAN — 



30CEAN 



— I 1 — 



25 30 



JUNE 



— r - 



10 



NAKNEK LAKE OUTLET 

 n=80 



Figure 9. — 'Percent daily age composition of sockeye 

 salmon by fresh-water and ocean age, Naknek River 

 escapement, 1962. 



that sometimes occur in the age composition and 

 perhaps produce or mask seasonal trends in age. 



AGE SEGREGATION ON THE SPAWNING GROUNDS 

 Results 



Tn figures 10 and 11 and table 7 the age compo- 

 sitions of fish sampled on the spawning grounds are 

 compared with the age compositions of fish sampled 

 at the Naknek River tagging site. In the figures 

 oidy the individual spawning grounds of each 

 lake with a sample size greater than 25 are com- 

 pared with the Naknek River samples. Com- 

 parisons are made on the basis of dominant age 

 groups (i.e., 4 2 , 5 2 , 5 3 , and 6 3 ) and fresh-water and 

 ocean age. A complete summary of all age cate- 

 gories present in the samples obtained from all 

 spawning grounds covered in this study is given 

 in table 7. 



Figures 10 and 11 and table 7 reveal marked 

 variation in the age composition of the spawning 

 ground samples when compared with each other 



jnn 



JLTUL 



fTTTTI 



Cvv3 Ei£li 



ESS 



Ml 



NAKNEK RIVER SAMPLES 

 WEIGHTED 



2 3 



2 3 



AGE GROUP 



'FRESH-WATER' OCEAN AGE 

 AGE 



Figure 10. — Percent composition of sockeye salmon 

 escapement for major spawning tributaries of Naknek 

 Lake by age group and fresh-water and ocean age, 1962. 



and with Naknek River samples. This strongly 

 suggests the segregation of populations by age on 

 the spawning grounds of the Naknek River 

 system. 



For the major spawning grounds of the Naknek 

 system, the frequencies of occurrence of the four 

 dominant age groups are arranged in a 4-by-9 

 contingency table (table 8). A chi-square test 

 of the hypothesis of like age compositions for the 

 spawning grounds being compared yielded a 

 value of x 2 =549.21, d.f. = 24, P=0.005. Since 

 the value of P is well below the adopted 0.01 

 level of significance, it constitutes convincing 

 evidence of unlike age compositions between the 

 areas compared and, therefore, segregation by 



474 



U.S. FISH AND WILDLfFE SERVICK 



