HKACHAM KT Al„: VrKON KIVKK CIirM SALMON POPULATION 



fall chum salmon populations during 1984-86. The most common allele at a locus was designated 100, 

 according to the mobility relative to that of the 100 allele. 



populations within countries, and between years within populations for Yukon River fall chum salmon 

 1984-86. P < 0.01; P < 0.05. 



fully to a long distance freshwater migration and 

 extreme winter conditions. 



Several biological characters differ between chum 

 salmon in the Yukon River and in British Colum- 

 bia. For Yukon River fall chum salmon, approx- 

 imately equal numbers of salmon mature, on aver- 

 age, at three and five years of age, although there 

 is annual variation (Buklis and Barton 1984). In the 

 Amur River, fall chum salmon mainly mature at four 

 and five years of age (Smirnov 1975). Similar results 



were recorded in our study. Yukon River chum 

 salmon matured at older ages and at smaller mean 

 lengths-at-age than did chum salmon in British Co- 

 lumbia. A general trend of younger ages at matur- 

 ity and increased mean lengths-at-age in southern 

 as compared with northern chum salmon popula- 

 tions has been reported by Salo (in press). This 

 trend may be a result of the earlier timing of fry 

 emergence and later timing of adult spawning of 

 more southern populations, allowing more time for 



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