Waterhouse, M.D., B.L. Sloss, and D.A. Isermann. 2014. Relationships among demographics and genetic diversity for walleye populations in northern Wisconsin. Transactions of the American Fisheries Society 143: 744-756.
The maintenance of genetic integrity is an important goal of fisheries management, yet the influences of population demographics and management actions on genetic diversity remain poorly understood. Consequently, we examined relationships among population demographics (abundance, recruitment, sex ratio and mean age of the breeding population), stocking intensity, and measures of genetic diversity (heterozygosity, effective number of alleles, allelic richness, Wright’s inbreeding coefficient, mean d2, mean relatedness, and pair wise population φ-st estimates) for 15 northern Wisconsin walleye populations. We also tested for potential demographic and genetic influences on walleye body condition and growth. Combinations of demographic factors explained between 47.1% and 85.9% of the variation in genetic diversity estimates. Skewed sex ratios seemed to induce genetic drift by increasing relatedness among individuals within the population, leading to negative effects on allelic richness and early growth. Levels of inbreeding were negatively related to both age-0 abundance and mean age, indicating effective population size was influenced by recruitment and generational overlap. Stocking may have induced outbreeding depression by altering allelic frequencies, leading to a negative relationship between the effective number of alleles and body condition. The isolation- by-distance pattern of genetic diversity was present in non-stocked populations, but was disrupted in stocked populations, suggesting that stocking affected genetic structure. Overall, demographic factors appeared to influence genetic diversity and stocking appeared to alter allelic frequencies and the genetic structure of walleye in Wisconsin, possibly resulting in disruption of local adaptation.