PPG/Ecologia and Departmento Ecologia, Universidade Federal do Rio Grande do Sul, CP 15007, Porto Alegre, RS 91501 970, Brazil.
Ecol Appl. 2013 Mar;23(2):392-407. doi: 10.1890/12-0429.1.
The long-term impacts of large hydroelectric dams on small-scale fisheries in tropical rivers are poorly known. A promising way to investigate such impacts is to compare and integrate the local ecological knowledge (LEK) of resource users with biological data for the same region. We analyzed the accuracy of fishers' LEK to investigate fisheries dynamics and environmental changes in the Lower Tocantins River (Brazilian Amazon) downstream from a large dam. We estimated fishers' LEK through interviews with 300 fishers in nine villages and collected data on 601 fish landings in five of these villages, 22 years after the dam's establishment (2006-2008). We compared these two databases with each other and with data on fish landings from before the dam's establishment (1981) gathered from the literature. The data obtained based on the fishers' LEK (interviews) and from fisheries agreed regarding the primary fish species caught, the most commonly used type of fishing gear (gill nets) and even the most often used gill net mesh sizes but disagreed regarding seasonal fish abundance. According to the interviewed fishers, the primary environmental changes that occurred after the impoundment were an overall decrease in fish abundance, an increase in the abundance of some fish species and, possibly, the local extinction of a commercial fish species (Semaprochilodus brama). These changes were corroborated by comparing fish landings sampled before and 22 years after the impoundment, which indicated changes in the composition of fish landings and a decrease in the total annual fish production. Our results reinforce the hypothesis that large dams may adversely affect small-scale fisheries downstream and establish a feasible approach for applying fishers' LEK to fisheries management, especially in regions with a low research capacity.
大型水电大坝对热带河流中小规模渔业的长期影响知之甚少。一种有前途的调查方法是将资源使用者的本地生态知识（LEK）与同一地区的生物数据进行比较和整合。我们分析了渔民的 LEK 准确性，以调查大型水坝下游的托坎廷斯河（巴西亚马逊）下游渔业动态和环境变化。我们通过对 9 个村庄的 300 名渔民进行访谈，估算了渔民的 LEK，并在其中 5 个村庄收集了 601 次鱼类上岸的数据，这些村庄距离大坝建成已有 22 年（2006-2008 年）。我们将这两个数据库相互比较，并与大坝建成前（1981 年）从文献中收集的鱼类上岸数据进行比较。基于渔民的 LEK（访谈）和渔业获得的数据在主要捕捞鱼类、最常用的渔具类型（刺网）甚至最常用的刺网网目尺寸方面是一致的，但在季节性鱼类丰度方面存在分歧。根据接受采访的渔民，蓄水后发生的主要环境变化是鱼类总体数量减少、一些鱼类数量增加，可能还有一种商业鱼类（Semaprochilodus brama）在当地灭绝。这些变化通过比较蓄水前后 22 年的鱼类上岸数据得到证实，这表明鱼类上岸的组成发生了变化，鱼类总产量下降。我们的结果证实了大型水坝可能对下游小规模渔业产生不利影响的假设，并建立了一种可行的方法，将渔民的 LEK 应用于渔业管理，特别是在研究能力较低的地区。
