Genetic differentiation of chinook salmon (Oncorhynchus tshawytscha) runs at Trinity River Hatchery, California

Starch gel electrophoresis was conducted to determine the genetic differentiation of chinook salmon Oncorhynchus tshawytscha runs from Trinity River Hatchery (TRH), California. A total of 389 fish were collected from September through December 1992 at TRH. Fifty-three presumptive genetic loci from 22 enzyme systems were screened for genetic differences. For the statistical analyses, these populations were divided into a priori run timing designations by TRH, where samples 1-4 constituted the spring run, and samples 5-11 constituted the fall run. Log likelihood statistics were used to analyze the five polymorphic loci. There were significant allele frequency differences between the two TRH designated runs. Cluster analysis using unweighted pair group method with arithmetic averages (UPGMA) compared TRH runs to geographical groupings from California, Oregon, and Idaho using genetic identity values. The resulting dendrogram showed that TRH spring- and fall-runs were genetically related and were derived from the same ancestral stock.