Identification of a Genetic Marker That Discriminates Ocean-Type and Stream-Type Chinook Salmon in the Columbia River Basin

A marker based on randomly amplified polymorphic DNA (RAPD), OT-38, was discovered that nonlethally discriminates between stream-type and ocean-type populations of chinook salmon Oncorhynchus tshawytscha in the Columbia River basin, including the threatened fall-run (ocean-type) and spring-run (stream-type) Snake River populations. This marker was developed by amplifying chinook salmon genomic DNA with a single RAPD primer, sequencing the termini of the polymorphic products, and designing primer pairs for allele-specific amplification. It was used to assay 18−80 individuals from several wild and hatchery populations differing in year-class, freshwater life history, and location along the Columbia River. OT-38 unambiguously distinguished ocean-type from stream-type populations in 93.1% of the chinook salmon sampled.