Data from: 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

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.北极红点鲑（Arctic Char，*Salvelinus alpinus*）被广泛认为是加拿大北极地区最重要的生计渔业鱼类物种。在该物种的自然分布范围内，亦存在针对北极红点鲑的商业捕捞渔业，其管理模式主要以单条河流为单元制定捕捞策略。但若管理单元或种群未能准确表征人口统计学意义上的独立种群，或是存在混合种群被同时捕捞的情况，该管理模式便可能不再适用。为确定该物种的最优管理空间尺度，我们对努纳武特地区剑桥湾区域的744尾北极红点鲑开展了微卫星DNA（microsatellite DNA）变异分析——该区域拥有该物种规模最大的商业捕捞渔业。本次采样设计特意匹配了当地商业捕捞的采样方案，以系统描述捕捞群体内部及群体间的遗传结构与遗传变异模式。此外，我们还纳入了地理距离更远的采样点位的北极红点鲑样本，为该区域的遗传种群结构分析提供空间参照背景。整体而言，我们在整个研究区域内检测到中度但显著的遗传结构分化。与之形成鲜明对比的是，商业捕捞种群间的遗传分化程度较弱，尤其是被归入威灵顿湾复合体的捕捞种群。针对这一弱分化现象，我们提出了三项假说：一是本次采样设计匹配了商业捕捞的实际方案；二是潜在的基因流动速率较高；三是种群有效规模较大。本研究结果对商业及生计渔业管理具有重要指导意义，其中包括“物种层级之下存在多个潜在保护单元”这一核心观点。