Evaluation of the native status of sea lampreys in Lake Champlain based on mitochondrial DNA sequencing analysis

Adult sea lampreys Petromyzon marinus parasitize a variety of recreationally, commercially, and ecologically important fishes in the north temperate Atlantic Ocean and some inland waters of North America, including the Great Lakes and Lake Champlain. This has resulted in the development of international, provincial, and state programs to suppress their abundance in some of these waters. This effort, in part, emanates from the normative status afforded sea lampreys in these lakes by management agencies. However, whether the sea lamprey is native to Lake Champlain has long been debated, and the outcome of this debate may impact the intensity of efforts to suppress their abundance there. We addressed this issue by using sequence analysis of the mitochondrial DNA control region. Resultant haplotype frequencies of sea lampreys from the Lake Champlain watershed were compared among sea lamprey collections made in multiple drainages within the Lake Ontario and Lake Superior watersheds and Atlantic coast rivers. We found no evidence of population structuring among tributaries within any of these four systems, but we did find highly significant genetic differentiation between systems. Haplotype diversity was low in the collections from the two Great Lakes and even more so in those from Lake Champlain compared with that in Atlantic coast rivers. Our genetic results are most consistent with the hypothesis that sea lampreys are native to Lake Champlain, having colonized the lake postglacially by one of several zoogeographic corridors.