1. Genidens barbus is a vulnerable marine migrant catfish with low fecundity, a complex life cycle (i.e. mouth breeding), and is the target of industrial and artisanal fisheries of several countries. This species regularly migrates from marine to freshwater environments of the south-western Atlantic.
2. The aim of this work was to delve deeper into the migration ecology of G. barbus, characterizing both its timing and potential environmental drivers. Furthermore, aspects of the population structure and reproduction of migrants in the lower Uruguay River were studied and the presence of juveniles in the adjacent estuarine recruitment area was evaluated.
3. Data from 11 years (2008–2018) of records of adult G. barbus captured by artisanal fisheries were used alongside relevant environmental variables that were recorded monthly. Reproductive biology (i.e. sex ratio, gonadosomatic index, fecundity, and oocyte size) was analysed for a period of 3 years (2016–2018). The juvenile abundance in the Río de la Plata estuary was evaluated seasonally.
4. A total of 935 adult individuals of G. barbus were captured, representing a total biomass of 3,123 kg. The migration timing was from early spring to early summer. The abundance of migrants strongly increased with river discharge, suggesting that this variable regulates the upriver migration. Furthermore, pre- and post-spawn females and males displaying mouth breeding were recorded during the study period, confirming G. barbus reproduction in the lower Uruguay River.
5. The results obtained suggest that G. barbus ascend to spawn in the freshwater environments upstream from the mouth of the Uruguay River. Then, adult males incubate and carry the embryos downstream, releasing juveniles in the Río de la Plata estuary.
6. This relevant information will help with the implementation of effective management polices (e.g. fishing restrictions during the reproductive period) for the presently unregulated fishery of this vulnerable species in the lower Uruguay River.

中文翻译：

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Río de la Plata 航海者：解读一条大型亚热带河流（乌拉圭河下游）中一种脆弱的海洋鲶鱼（Genides barbus）的迁徙生态

1. Genidens barbus是一种脆弱的海洋洄游鲶鱼，繁殖力低，生命周期复杂（即嘴繁殖），是一些国家工业和手工渔业的目标。该物种经常从大西洋西南部的海洋环境迁移到淡水环境。
2. 这项工作的目的是深入研究G. barbus的迁移生态，表征其时间和潜在的环境驱动因素。此外，还研究了乌拉圭河下游移民的人口结构和繁殖方面，并评估了邻近河口招募区幼鱼的存在情况。
3. 手工渔业捕获的成年G. barbus记录的 11 年（2008-2018 年）数据与每月记录的相关环境变量一起使用。生殖生物学（即性别比、性腺指数、生育力和卵母细胞大小）分析了 3 年（2016-2018 年）。拉普拉塔河口的幼鱼丰度是季节性评估的。
4. 总共捕获了 935 只G. barbus成年个体，总生物量为 3,123 kg。迁移时间是从早春到初夏。移民的丰度随着河流流量的增加而显着增加，表明该变量调节了上游迁移。此外，在研究期间记录了产卵前和产卵后雌性和雄性的嘴繁殖，证实了乌拉圭河下游的G. barbus繁殖。
5. 获得的结果表明，G. barbus上升到乌拉圭河口上游的淡水环境中产卵。然后，成年雄性孵化并将胚胎带到下游，在拉普拉塔河口释放幼鱼。
6. 这些相关信息将有助于为乌拉圭河下游目前不受管制的这种脆弱物种渔业实施有效的管理政策（例如在繁殖期限制捕捞）。