Towards a sustainable Arctic fishery: Population genomics of lake whitefish in a hybrid species complex
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Genetic variation is an important predictor of population persistence under changing or stressful environmental conditions. Consequently, efforts to preserve genetic variation by identifying genetically distinct populations and delineating management units are primary goals of conservation genetics and fisheries management. Accelerated melting of sea ice in the lower Northwest Passage (LNWP) in Nunavut has recently opened the passage to shipping, providing an opportunity for fishery establishment. Nunavut communities have some of the highest rates of food insecurity across Canada, so the commercial harvest of profitable fish species could help to alleviate this crisis. However, sustainable fishery management in the LNWP requires the characterization of genetic structure in focal species to determine the best practices for managing demographically independent populations and, over the longer term, conserving genetic variation. The lake whitefish (Coregonus clupeaformis) is an important commercial species across Canada, is abundant in the LNWP, and is valued by the local people in Nunavut. However, lake whitefish have only recently expanded their range into this area, and the distribution of their genetic variation across the LNWP is unknown. Using genome-wide panels of single nucleotide polymorphisms, my results suggest one genetic population of lake whitefish in the LNWP. However, using putatively adaptive markers, I find weak evidence for two to three units of lake whitefish in the area. Further, I uncover genetic indication of hybridization between lake whitefish, Arctic cisco (C. autumnalis), and sardine cisco (C. sardinella) in the LNWP. Admixture among these species may make setting sustainable catch limits for lake whitefish challenging, as fishing pressures will likely decrease the abundance and genetic diversity of each species. Thus, my work aims to inform fishing regulations that reduce the relative exploitation of genetically distinct units of lake whitefish and minimize impacts of harvest on hybrids and their parental species. Setting reasonable fishing limits and preserving the genetic diversity of lake whitefish in the LNWP will reduce the likelihood of a fishery collapse, and increase probability for the species to become a sustainable resource for the people of Nunavut.
URI for this recordhttp://hdl.handle.net/1974/27468
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