Sea lamprey (Petromyzon marinus) are an extremely harmful invasive species in the Great Lakes. The species decimated native fish populations, causing harm to the ecosystem. To aggressively respond to the invasion, a bi-national program has been dedicated to reducing sea lamprey numbers. Control of lamprey populations includes physical barriers to prevent spawning adults from entering streams, and applications of lampricide (3-trifluormethlyl-4-nitrophenol or TFM) to kill larvae living in stream substrates. Annual assessments of adult sea lamprey are conducted, but are limited to a small number of streams. This study generated genetic data for sea lamprey larvae to reconstruct parental genotypes and estimate effective size of spawning populations. In Chapter 1, we use this information to evaluate the magnitude of barrier failures in three streams. In Chapter 2, we genotyped larvae from 18 streams with different physical characteristics across the Great Lakes and examined the effects of different factors that could affect spawning populations. Additionally, we generated simulated sea lamprey populations to evaluate the effects of sample size, number of genotypes, and true effective population size on the accuracy and precision of genetic estimates. Our simulations showed that a sample size of at least 100 individuals, along with maximization of SNP set size, allows for accurate estimates for all effective population sizes tested. Our work demonstrates that pedigree-based inferences can be effectively used as a management tool to characterize sea lamprey spawning abundance, poorly understood aspects of the species mating system, and relationships between adult reproductive success and associated stream characteristics.
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