FISHERY BULLETIN: VOL, 86, NO. 2 



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FORK LENGTH (cm) 



Figure 3. — Gonadal-somatic index (testis wt/total body wt) x 100 of juvenile coho salmon vs. 

 length of fish for July, August, and September 1981-84. Only data for those testes actually 

 weighed are shown. 



prised a higher percentage of fish larger than 300 

 mm FL in August 1981 and larger than 350 mm 

 FL in September 1982, 1983, and 1984. These 

 results indicate that most juvenile coho salmon 

 caught off Oregon and Washington were not sexu- 

 ally precocious. Thus, the relatively large catches 



of juvenile coho salmon in late summer are ex- 

 plained by lack of strong migrational tendencies 

 of juvenile coho salmon in this region and not by 

 a high proportion of precocious "jacks" that re- 

 sided in this region as a prelude to re-entry of 

 streams for spawning. 



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