Lehnert Sarah J, Baillie Shauna M, MacMillan John, Paterson Ian G, Buhariwalla Colin F, Bradbury Ian R, Bentzen Paul
Fisheries and Oceans Canada Northwest Atlantic Fisheries Centre St. John's NL Canada.
Marine Gene Probe Lab Biology Department Dalhousie University Halifax NS Canada.
Evol Appl. 2020 Feb 20;13(5):1069-1089. doi: 10.1111/eva.12923. eCollection 2020 May.
Many populations of freshwater fishes are threatened with losses, and increasingly, the release of hatchery individuals is one strategy being implemented to support wild populations. However, stocking of hatchery individuals may pose long-term threats to wild populations, particularly if genetic interactions occur between wild and hatchery individuals. One highly prized sport fish that has been heavily stocked throughout its range is the brook trout (). In Nova Scotia, Canada, hatchery brook trout have been stocked since the early 1900s, and despite continued stocking efforts, populations have suffered declines in recent decades. Before this study, the genetic structure of brook trout populations in the province was unknown; however, given the potential negative consequences associated with hatchery stocking, it is possible that hatchery programs have adversely affected the genetic integrity of wild populations. To assess the influence of hatchery supplementation on wild populations, we genotyped wild brook trout from 12 river systems and hatchery brook trout from two major hatcheries using 100 microsatellite loci. Genetic analyses of wild trout revealed extensive population genetic structure among and within river systems and significant isolation-by-distance. Hatchery stocks were genetically distinct from wild populations, and most populations showed limited to no evidence of hatchery introgression (<5% hatchery ancestry). Only a single location had a substantial number of hatchery-derived trout and was located in the only river where a local strain is used for supplementation. The amount of hatchery stocking within a watershed did not influence the level of hatchery introgression. Neutral genetic structure of wild populations was influenced by geography with some influence of climate and stocking indices. Overall, our study suggests that long-term stocking has not significantly affected the genetic integrity of wild trout populations, highlighting the variable outcomes of stocking and the need to evaluate the consequences on a case-by-case basis.
许多淡水鱼种群面临数量减少的威胁，越来越多的情况是，放流孵化场培育的个体成为一种支持野生种群的实施策略。然而，投放孵化场培育的个体可能会对野生种群构成长期威胁，特别是当野生个体与孵化场培育的个体之间发生基因相互作用时。溪红点鲑是一种在其分布范围内被大量投放的备受珍视的游钓鱼类。在加拿大新斯科舍省，自20世纪初以来就开始投放孵化场培育的溪红点鲑，尽管持续进行投放工作，但近几十年来种群数量仍出现了下降。在本研究之前，该省溪红点鲑种群的遗传结构尚不清楚；然而，鉴于与孵化场放流相关的潜在负面后果，孵化场计划有可能对野生种群的遗传完整性产生了不利影响。为了评估孵化场补充放流对野生种群的影响，我们使用100个微卫星位点对来自12个河流系统的野生溪红点鲑以及来自两个主要孵化场的孵化场溪红点鲑进行了基因分型。对野生鳟鱼的遗传分析揭示了河流系统之间和内部广泛的种群遗传结构以及显著的距离隔离现象。孵化场的种群在基因上与野生种群不同，大多数种群显示出有限的或没有孵化场基因渗入的证据（孵化场血统<5%）。只有一个地点有大量来自孵化场的鳟鱼，且该地点位于唯一一条使用当地品系进行补充放流的河流中。流域内孵化场放流数量并未影响孵化场基因渗入的程度。野生种群的中性遗传结构受地理因素影响，同时也受到气候和放流指数的一定影响。总体而言，我们的研究表明长期放流并未对野生鳟鱼种群的遗传完整性产生显著影响，突出了放流结果具有变异性以及需要逐案评估后果的必要性。
