Genetic Population Structure of Muskellunge in the Great Lakes

We quantified genetic relationships among muskellunge from 15 areas of the Great Lakes to determine the extent and distribution of measurable population structure and to identify appropriate spatial scales for fishery management and genetic conservation.  We hypothesized that muskellunge from each area represented genetically distinct populations, which would be evident from analyses of genotype data obtained from 13 microsatellite loci.  A total of 691 muskellunge were collected, and sample sizes ranged from 10-127 for each hypothetical population.  Results from a suite of analyses (including pairwise comparisons of genetic differentiation, the Bayesian clustering algorithm generated with the program STRUCTURE, analysis of molecular variance, and tests of isolation by distance) indicated the presence of nine distinct genetic groups, including two that were only about 50 km apart.  Geographic proximity and low habitat complexity seemed to facilitate genetic similarity of muskellunge among areas, whereas muskellunge from areas of greater habitat heterogeneity exhibited high differentiation.  Muskellunge from most areas contained private alleles, and mean within-area genetic variation was similar to that reported for other freshwater fishes.  Therefore, we recommend that genetically distinct groups of muskellunge be considered independent fisheries, and individual spawning and nursery habitats be protected to conserve the evolutionary potential of muskellunge.