Muskellunge Genetic Integrity and Structure in the Great Lakes: Implications for Propagation Programs

Muskellunge (Esox masquinongy) have experienced considerable population declines and several extirpations in and around the Great Lakes.  While few populations have persisted relatively unchanged, others have benefited from restoration efforts, and others still have yet to be restored.  Additionally, historic and contemporary stocking of Great Lakes and non-Great Lakes strain Muskellunge poses a threat to the genetic integrity of remaining populations.  Therefore, a broader understanding of the degree of current genetic differentiation among all major Great Lakes populations, including those existing in key tributaries is needed.  Our goal was to describe the genetic diversity within and differentiation among all major Great Lakes area populations and to determine the extent of introgression that has resulted from past Muskellunge stocking efforts.  Thirteen microsatellite loci were used to characterize genetic diversity and structure of >1,800 Muskellunge from >40 locations throughout the Great Lakes and associated inland drainages.  Bayesian and maximum likelihood results suggest discrete genetic structure both east/west and inland-Great Lakes proper, including significant fine-scale structure at various locations throughout the Great Lakes.  Genetic diversity, molecular variance, and other genetic measures were used to identify reasonable genetic management units (stocks) and potential brood sources for these various stocks.