LAUSR

AbstractNative and nonnative salmonids within the same genus sometimes hybridize, and the hybrids are often difficult to visually distinguish from parental species. We compared phenotypic delineations (based on several visual characteristics) and genotypic screening (using seven nuclear DNA loci) for 323 fish collected from an Idaho stream where Yellowstone Cutthroat Trout O. clarkii bouvieri were introgressed with Rainbow Trout O. mykiss to evaluate our ability to visually distinguish Yellowstone Cutthroat Trout from Rainbow Trout and hybrids. Assuming that the genotypes were 100% accurate, correct phenotypic classification was highest for Yellowstone Cutthroat Trout (the genotype confirmed the phenotype 94% of the time), followed by hybrids (79%) and Rainbow Trout (71%). All errors were between pure and hybrid fish. All of the measured phenotypic characteristics were useful for differentiating Yellowstone Cutthroat Trout from hybrids, but the most informative characteristics were the lack of a white lea...