Abstract. 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)(2007)(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.

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The management of small-scale freshwater fisheries in Amazon has been based usually on surveys of urban markets, while fisheries of rural villages have gone unnoticed. We compared the fishing characteristics (catch, effort and selectivity) between an urban market and five small villages in the Lower Tocantins River (Brazilian Amazon), downstream from a large reservoir. We recorded 86 and 601 fish landings in the urban market and villages, respectively, using the same methodology. The urban fishers showed higher catch per unit of effort, higher amount of ice (related to a higher fishing effort, as ice is used to store fish catches) and larger crew size per fishing trip, but village fishers had a higher estimated annual fish production. Conversely, urban and village fishers used similar fishing gear (gillnets) and the main fish species caught were the same. However, village fishers showed more diverse strategies regarding gear, habitats and fish caught. Therefore, although it underestimated the total amount of fish caught in the Lower Tocantins River region, the data from the urban market could be a reliable indicator of main fish species exploited and fishing gear used by village fishers. Monitoring and management should consider the differences and similarities between urban and rural fisheries, in Amazon and in other tropical regions.

Synopsis Maenodon aneylodon was obtained from landings in Santos Port (São Paulo State) of fish caught monthly by commercial vessels~ on the southern coast of Brazil during September 1976 to August 1977. The measurements of total lenght~ total weight determination of sex and maturity stages were made. The food items found in stomach contents were: shrimp (Antem~ia longin~)~ fishes (Panalonehu~ b~ilien6~, Maenodon aneylodon, Tniehiu~ lept~, Gadidae~ Engraulidae)~ molluscs (Loliginidae~ Bivalvia) and Stomatopoda. Widening of food spectrum was observed in winter. The index of preponderance showed that immature females~ immature and mature males fed predominantly on shrimp~ while mature females fed mainly on fishes. During spring and summer (spawning season) M. aneylodon exhibited relatively low percentage of full stomachs. Cannibalism was encountered more intensively for mature fish.

O estudo descreve os apetrechos de pesca utilizados pelos pescadores artesanais, bem como as operações de pesca realizadas no reservatório da Usina Hidrelétrica de Tucuruí. A rede malhadeira xa é o principal apetrecho e o anzol na forma de linha de mão é a segunda arte de pesca utilizada no reservatório. A utilização dos apetrechos de pesca é limitada pelos obstáculos (paliteiros) e oscilação da profundidade no reservatório.