**The title, authors, and abstract for this completion report are provided below

**The title, authors, and abstract for this completion report are provided below. For a copy of the completion report, please contact the GLFC via e-mail or via telephone at 734-662-3209**

Conservation genetics of deepwater sculpin in the Great Lakes

Tom Sheldon¹, Nick Mandrak², Chris Wilson³, Nathan Lovejoy^1,4

1Dept. of Zoology, University of Manitoba, Z320 Duff Roblin Bldg, Winnipeg, MB R3T 5A3

2GLLFAS, Fisheries and Oceans, Burlington, ON L7R 4A6

3OMNR, Trent University, Peterborough, ON K9J 8N8

4Dept. of Life Sciences, University of Toronto at Scarborough, Toronto ON M1C1 A4

Abstract

The deepwater sculpin, Myoxocephalus thompsonii, is a North American benthic lake-dwelling fish species whose distribution, biology, habitat and taxonomic structure are poorly understood. Deepwater sculpin have historically occurred in the Great Lakes. The species was thought to be extirpated from Lake Ontario, but has since been rediscovered in small numbers. To improve understanding of the deepwater sculpin, especially in the Great Lakes, we conducted a range-wide survey of the species and a study of its biology, including diet, age structure, habitat, and genetics. Diet analyses of deepwater sculpin collected revealed the importance of Diporeia spp., Mysis and chironomid larvae, while age analyses suggest that deepwater sculpin are much longer-lived than previously thought. Habitat analyses suggest that the presence of deepwater sculpin is intimately linked to highly oligotrophic lakes and, more specifically, extremely low (<7 ºC) benthic water temperatures. Phylogenetic analyses of the mitochondrial DNA control region and ATPase6,8 sequences of Myoxocephalus thompsonii from the Great Lakes and 19 additional inland lakes across Canada, as well as marine and freshwater fourhorn sculpin (M. quadricornis) from 11 locations across the arctic support the distinction of deepwater sculpin and fourhorn sculpin (including freshwater fourhorn sculpin) as two distinct species. Additionally, three well-defined mitochondrial haplotype lineages of deepwater sculpin within Canada support the historical isolation of deepwater sculpin in Mississippian, Southwestern, and Atlantic refugia. All deepwater sculpin within the Laurentian Great Lakes belong to the Mississippian lineage.