A number of loci known or suspected to be monomorphic were not included in the analysis, so values shown are relative rather than unbiased estimates of true genetic distance. Proportion of initial genetic variability remaining in a simulated chinook salmon population after periods of time up to 100 years. N b is the effective number of breeders per year. Distribution of alleles at various frequencies found in samples from 177 chinook salmon populations in the Pacific Northwest. Table 1 .
Average heterozygosity values a for spring and fall chinook salmon from the Columbia River Basin.
Regional values are means based on the number of stocks indicated in parentheses. A number of loci known or suspected to be monomorphic were not included in the analysis, so values shown are relative rather than unbiased estimates of total heterozygosity.