Genetic Stock Structure of Anadromous Arctic Char in Canada’s Central Arctic: Potential Implications for the Management of Canada’s Largest Arctic Char Commercial Fishery

Abstract

The Arctic Char Salvelinus alpinus is widely considered the most important subsistence fish species in the Canadian Arctic. Throughout the species’ range, commercial fisheries for Arctic Char also exist, the management of which primarily follows river-specific harvest strategies. Such an approach, however, may not be appropriate if the management unit or stock does not accurately reflect a demographically independent population or if mixtures of populations are being harvested. We assayed microsatellite DNA variation among 744 Arctic Char from the Cambridge Bay region, Nunavut, where the largest commercial fishery for the species exists, in order to identify the most appropriate spatial scale at which these stocks should be managed. Our sampling design specifically mirrored that of the commercial fishery in order to describe patterns of genetic structure and genetic variation within and among the harvested component. We also included Arctic Char from more geographically distant sampling locations to provide a spatial context for genetic stock structuring in the region. Overall, we found moderate but significant structure across the entire study area. In contrast, commercially harvested stocks were weakly differentiated, especially among the stocks that are considered part of the Wellington Bay complex. We propose several hypotheses for this weak differentiation, including (1) our sampling design that mirrored the commercial harvest, (2) high rates of potential gene flow, and (3) large effective population sizes. Our results may have important implications for commercial and subsistence fisheries management, including the notion that there are several potential units of conservation below the species level.

Received September 29, 2015; accepted August 17, 2016 Published online November 28, 2016

ACKNOWLEDGMENTS

This study was made possible by the approval and participation of the Ekaluktutiak Hunters and Trappers Organization (EHTO), which also provided field assistants and boat guides to aid in sample collection. Additionally, members of the EHTO and residents of Cambridge Bay shared their extensive knowledge of Arctic Char biology in the region; we are particularly grateful to Brenda Sitatak, Alice Maghagak, Beverly Maksagak, Dianne Mala, Jimmy Haniliak, Bobby Greenley, Peter Evalik, George Angohiatok, and James Panioyak. Over the years, field assistance was provided by Bobby Maghagak, Richard and Mary Ekpakohak, Jack (Meyok) Omilgoitak, Kevin Kanayak, Darcy Kanayok, Devon Oniak, Jimmy and Ruby Haniliak, Johnny Pedersen, Mitch Leclaire and Chris McDermid. We also thank the commercial fishers for their ongoing support of our stock assessment work and for sharing their knowledge of Arctic Char and the Cambridge Bay commercial fishery; we are especially grateful to Jack Ekpakohak and Brent Nakashook. We appreciate the employees of Kitikmeot Foods Ltd., who provided ongoing support for our commercial plant sampling program. In particular, we thank Denise LeBleu for providing invaluable support and friendship throughout the years and Annie Anavilok and Alice Keyok for conducting the plant sampling. We are also grateful to Chris McDermid for assistance in the laboratory; Colin Gallagher for providing the HOR, KUJ, and QUN samples; and James Reist and Jim Johnson for providing the NAU samples. Carolyn Bakelaar assisted with map creation. Funding for sample collection and laboratory analyses was provided by the Nunavut Wildlife Management Board and through Nunavut Implementation Funds from Fisheries and Oceans Canada. Logistical support was provided by Natural Resources Canada through the Polar Continental Shelf program. Three anonymous reviewers supplied comments that greatly improved the manuscript. Data are available from the Dryad Digital Repository, DOI: 10.5061/dryad.8ss09.