Comment on “Gene flow increases temporal stability of Chinook salmon (Oncorhynchus tshawytscha) populations in the Upper Fraser River, British Columbia, Canada”Appears in Can. J. Fish. Aquat. Sci. 66: 167–176.

Abstract

Temporally stable genetic structure among salmonid populations has been reported in many studies, although the time span evaluated in most studies is limited to 10 years or less. This result has important implications in conservation and management of Pacific salmon ( Oncorhynchus spp.) and ramifications for the construction and application of genetic databases for stock identification of fish sampled from mixed-stock fisheries. Walter et al. (2009. Can. J. Fish. Aquat. Sci. 66: 167–176) failed to consider recent studies providing evidence that their conclusion “the overall magnitude of temporal within-population variation exceeding that of among-population variation” for the populations under study may be invalid for Fraser River Chinook salmon ( Oncorhynchus tshawytscha ) populations. Their estimation of rates and patterns of migration among Chinook salmon populations also provided results that are difficult to reconcile with published information. Evaluation of the experimental designed employed by Walter et al. (2009) indicates that their sample sizes were too small to estimate reliably genetic variation among or within populations. Extrapolation of their conclusions relating temporal instability of population structure to other Chinook salmon populations or indeed other salmonid species is unwarranted.