Muskellunge Management: Fifty Years of Cooperation Among Anglers, Scientists, and Fisheries Biologists

Water Wolves and Tigers: Testing for Directional Hybridization and Introgression between Northern Pike and Muskellunge [Abstract]

Cait Nemeczek and Chris C. Wilson


Tiger muskellunge (Muskellunge Esox masquinongy × Northern Pike E. lucius) are commonly stocked in the United States, but not in Canada. Much research has been conducted on the culture and stocking of these fish; however, there has been little research on natural hybrids or the genetics of tiger muskellunge. Hybridization and introgression occur within and among different taxa and can have both positive and negative impacts. Hybridization can lead to speciation events and can also be used for genetic rescue, but introgression has the potential to cause extinction of populations when hybrids repeatedly backcross with parental species. Studies on hybridization utilize species-specific markers because unique differences between species allows for more reliable and accurate detection of hybrids. In this study, the cytochrome b region of mitochondrial DNA (mtDNA) was sequenced from 60 tiger muskellunge from various lakes in Ontario, as well as hatcheries and lakes in New York, Wisconsin, and Minnesota, in order to determine whether tiger muskellunge had Muskellunge or Northern Pike mtDNA. Since mtDNA is maternally inherited, the data allowed the directionality of hybridization to be determined. Tiger muskellunge were genotyped using 20 nuclear microsatellite loci to confirm hybridization and to test for introgression. Muskellunge and Northern Pike have historically faced population declines, and information on hybridization between these two species may help to understand these declines, particularly if introgression is occurring. Anthropogenic effects such as habitat fragmentation are known to increase the rate of hybridization in species, and if there is evidence of introgression, here would be a need for management action in order to protect genetically distinct populations of both Muskellunge and Northern Pike.