DNA-Based
Stock-of-Origin Assignments of Chinook
Todd W. Kassler, WDFW Molecular Genetics Laboratory
Jennifer Von Barge, WDFW Molecular Genetics Laboratory
An evaluation of 20
individual baseline collections from five stocks (spring stocks - upper Yakima
River, Naches River, and American River; fall stocks – Marion Drain and lower
Yakima River) in the Yakima River basin was conducted to determine if the
individual temporal collections were genetically similar and to assess the
relationships among the five stock groups.
A stock-of-origin assignment procedure was used to estimate the
percentages of smolts from each of five stocks groups
outmigrating past Chandler Trap (Yakima River) from
January – July 2006. Mixture analysis
was conducted on a proportional subsample of 1,500 smolts
for five time strata (January – February, March, April, May, and June – July)
during the outmigration. The largest
percentage of outmigrating smolts
in the first four time strata was from the upper Yakima River stock while the
June – July time stratum was dominated by the lower Yakima River fall and
Marion Drain fall stocks with over 89% of the total assignments. Comparison of morphological assessment and
genetic assignment as a spring or fall Chinook smolt
conducted for all time strata identified 1,438/1,485 (96.8%) smolts the same.