Identifying fish spawning areas is of great ecological and conservation importance as fishes are suffering increasing threats levels from anthropogenic activities. However, to date very few studies have done so in the Amazon basin. In the Beni River located in the upper Madeira basin, fishers reported that a particular ecotone near Rurrenabaque city was a fish reproduction area. To test the importance of this zone as a spawning site, we conducted an ichthyoplankton survey during the month when reproduction is most likely to occur. The specific identification of larvae and eggs was made with a metabarcoding analysis. With this approach 13 different fish species of high importance for regional and local fisheries were identified, including the long-distance migratory gilded catfish (Brachyplatystoma rousseauxii), considered as endangered in the upper Madeira. Combining the development time of morula-gastrula egg stages with the integrated current velocity of the river, we identified a spawning area that ranges between the last gravel beaches close to Altamarani community and the San Miguel del Bala community on top of Suse strait, the last foothill of the Andes. This spawning area further extends upstream in the Madidi and Pilon Lajas protected areas and Tacana and Tsimane indigenous communities, when considering eggs in final embryo stage. This portion of the Beni River, at the Andean foothills, is heavily impacted by anthropogenic activities, ranging from unmanaged fisheries to contamination coming from the extraction of fluvial aggregates, upstream gold mining, deforestation associated with a sugar cane mill, an existing downstream dam, and projected upstream dam projects. Some urgent solutions for the conservation of this already impacted area are proposed. Confirming fish spawning zones, although difficult, is crucial to inform the definition of priority areas for conservation and management measures, in particular when these sites host endangered species.

由于鱼类正遭受来自人为活动的日益严重的威胁，因此确定鱼类产卵区具有重要的生态和保护意义。但是，迄今为止，在亚马逊盆地尚无研究。渔民报告说，在马德拉群岛上游盆地的贝尼河上，Rurrenabaque市附近的一个特定过渡带是鱼类繁殖区。为了测试该区域作为产卵场的重要性，我们在最有可能发生繁殖的月份进行了鱼鳞浮游动物调查。幼虫和卵的特异性鉴定是通过元条形码分析进行的。通过这种方法，确定了13种对区域和地方渔业具有重要意义的鱼类，包括长途mi游鱼（Brachyplatystoma rousseauxii）），被认为在马德拉岛上濒危。结合桑ula卵卵期的发育时间和河流的综合流速，我们确定了一个产卵区，范围在靠近Altamarani社区的最后一个砾石海滩和位于Suse海峡顶部的San Miguel del Bala社区之间，即最后一个安第斯山脉的山麓小丘。当考虑在最后胚胎阶段产卵时，该产卵区进一步延伸到Madidi和Pilon Lajas保护区以及Tacana和Tsimane土著社区的上游。贝尼河的这一部分位于安第斯山麓，受到人为活动的严重影响，范围从不受管理的渔业到河流集料的提取，上游金矿开采，与甘蔗磨坊相关的森林砍伐，现有下游大坝，并计划上游大坝工程。为保护这个已经受到影响的地区提出了一些紧急的解决方案。确定鱼产卵区虽然很困难，但对于确定保护和管理措施的优先领域至关重要，特别是在这些场所收容濒临灭绝物种的时候。