Nine biochemical characteristics of female Oncorhynchus keta subpopulations that migrate to three streams (Namdaechun, Myeongpachun, Oshipchun) in Gangwon, Korea, were evaluated during November 2006: aspartate aminotransferase, alanine aminotransferase, creatine kinase, triglyceride, cholesterol, glucose, hemoglobin, and urea in the blood and RNA/DNA in muscle. The three subpopulations were identical morphologically, but differed in their biochemical characteristics. The RNA/DNA ratio could be useful for distinguishing the subpopulations. RNA/DNA ratios of the Namdaechun and the Myeongpachun and Oshipchun subpopulations were $3.52{pm}0.7$ and $2.9{pm}0.7$ and $2.4{pm}0.8$, respectively. The difference was statistically significant (P<0.05). By contrast, the blood parameters were somewhat ambiguous.