Department of Biosciences, Durham University, South Road, Durham, DH1 3LE, England, United Kingdom.
Section for Freshwater Fisheries Ecology, National Institute of Aquatic Resources, Technical University of Denmark, Vejlovej 39, Silkeborg, Denmark.
J Environ Manage. 2020 May 15;262:110317. doi: 10.1016/j.jenvman.2020.110317. Epub 2020 Feb 27.
Fishways are commonly employed to improve river connectivity for fishes, but the extent to which they cater for natural phenotypic diversity has been insufficiently addressed. We measured differential upstream passage success of three wild brown trout (Salmo trutta) phenotypes (anadromous, freshwater-resident adult and parr-marked), encompassing a range of sizes and both sexes, at a Larinier superactive baffle fishway adjacent to a flow-gauging weir, using PIT telemetry (n = 160) and radio telemetry (n = 53, double tagged with PIT tags). Fish were captured and tagged downstream of the weir in the autumn pre-spawning period, 2017, in a tributary of the River Wear, England, where over 95% of tributary spawning habitat was available upstream of the weir. Of 57 trout that approached the weir-fishway complex, freshwater-resident adult and parr-marked phenotypes were less successful in passing than anadromous trout (25%, 36%, and 63% passage efficiency, respectively). Seventy-one percent of anadromous trout that passed upstream traversed the weir directly. Although the fishway facilitated upstream passage, it was poor in attracting fish of all phenotypes (overall attraction efficiency, 22.8%). A higher proportion (68.2%) of parr-marked trout that approached the weir were male and included sexually mature individuals, compared with that of freshwater-resident (37.8%) and anadromous trout (37.0%). The greater passage success of anadromous trout was likely due to their greater size and locomotory performance compared to the other phenotypes. Barriers and fishways can act as selection filters, likely the case in this study, and greater consideration needs to be given to supporting natural diversity in populations when proposing fishway designs to mitigate river connectivity problems.
鱼道通常用于改善鱼类的河流连通性，但它们在多大程度上满足了自然表型多样性的需求还没有得到充分的解决。我们使用 PIT 遥测技术（n=160）和无线电遥测技术（n=53，双标签 PIT 标签），在靠近流量测量堰的 Larinier 超级挡板鱼道上，测量了三种野生棕色鳟鱼（Salmo trutta）表型（洄游型、淡水居留成年型和幼鱼标记型）的上游通过成功率差异，这些表型涵盖了一系列大小和性别。2017 年秋季产卵前，在英格兰 Wear 河的一条支流中，我们在堰下游捕获并标记了这些鱼，该支流中超过 95%的支流产卵栖息地位于堰上游。在 57 条接近堰-鱼道综合体的鳟鱼中，淡水居留成年型和幼鱼标记型的通过效率低于洄游型鳟鱼（分别为 25%、36%和 63%）。通过上游的洄游型鳟鱼中有 71%直接穿过了堰。虽然鱼道促进了上游的洄游，但它对吸引所有表型的鱼类效果不佳（整体吸引力效率为 22.8%）。与淡水居留型（37.8%）和洄游型（37.0%）相比，接近堰的幼鱼标记型鳟鱼中有更大比例（68.2%）为雄性，包括性成熟个体。洄游型鳟鱼较高的通过成功率可能是由于它们与其他表型相比体型更大、运动能力更强。障碍物和鱼道可以作为选择过滤器，在本研究中很可能就是这种情况，因此在提出缓解河流连通性问题的鱼道设计时，需要更加关注支持种群的自然多样性。
