Figure 14. — Samples of pink salmon measured from 

 mldeye to posterior end of hypural plate. 



mean of 1,216 females was 45 cm. Although 

 the means for combined samples indicated 

 similarity in size of sexes of both years, the 

 mean lengths for early females were sig- 

 nificantly larger in 1961 than the means for 

 early males from the same areas (figs. 16 and 

 17). 



Racial indications by time of spawning . -- 

 There were few pronovinced differences in mean 

 lengths of fish relative to time of spawning 

 season in I960; however, late females were 

 significantly smaller than early females from 

 the same areas (fig. 16). In 1961 there were 

 more obvious seasonal differences in size of 

 spawners. Late males were significantly larger 

 than early males in mean length (fig. 17), 

 and late females were significantly larger 

 than early females. 



Racial indications by location of spawn- 

 ing . --Samples of 100 males and 100 females 

 from Middle Slough and Little Creek areas 

 were measured August 9 and 11, 1960. These 

 fish were significantly smaller in mean length 

 than early spawners from other portions of 

 Olsen Bay spawning groxinds (fig. 16). In 1961, 

 pink salmon spawned in Middle Slough and 



30 

 20 

 10 





 30 

 20 

 10 





 30 

 20 

 10 





 30 

 20 

 10 



100 LATE-RUN MALES 

 X I960 



100 LATE-RUN FEMALES 

 I960 



214 LATE-RUN MALES 

 1961 





140 LATE-RUN FEMALES 

 1961 

 X 



i«- 



30 35 40 45 50 



MIDEYE-HYPURAL PLATE LENGTH (CM.) 



55 



Figure 15. — Length frequency distributions of adult pink 

 salmon from the West Fork of Olsen Creek, 1960-61. 



Little Creek during the late. run but not during 

 the early run. They were not different in size 

 from other late spawners at Olsen Bay. 



Sex Ratios 



Males generally predonninate on the spawn- 

 ing grounds during the early stages of salmon 

 runs, but as the run progresses, females 

 gradually increase in relative abundance until 

 they outnumber males. Sometimes the typical 

 progression in sex ratios is followed by a 

 second such progression the same season, 

 giving a clear indication of so-called early- 

 and late-run salmon. Proof of true racial or 

 genetic identities should be sought by other 

 means, such as serological studies. Never- 

 theless, seasonal changes in sex ratios at 

 Olsen Bay were examined for indications of 

 racial identities. 



Weir carcass counts, I960 . --In 1960, 8,744 

 pink salmon carcasses that drifted downstream 

 onto the weirs were tallied by sex (table 6). 

 Carcasses were observed over an 8-week 

 period extending from July 17 to Septennber 5. 

 There were no important differences in total 



16 



