Amazonian rivers are characterized by a strongly seasonal flood pulse, which is being altered by ongoing and planned hydropower development across the basin. Changes in hydrology have a cascade of physical, ecological, and social effects, and some ecohydrological changes in the Amazon are expected to be irreversible. To better understand these linkages, we investigated shared trends and causal factors driving fish catch in a major Amazonian tributary before dam construction to derive relationships between catch and natural hydrologic dynamics that can be used to assess likely post‐dam fisheries impacts. We applied a time series‐based dimension reduction technique (dynamic factor analysis) to investigate dynamics in fish catch across 10 commercially important species using daily fish landings and hydrological data. We found a 4‐trend dynamic factor model to best fit the observed data, with fitted trends exhibiting variation representative of seasonal and longer‐term hydrologic variation. We next considered 11 candidate explanatory time series and found the best dynamic factor model used 4 explanatory variables: maximum water level, flooding duration, previous year's flow, and rate of change in flow; however, each species showed a unique response to this set of hydrological variables. Species‐specific responses suggested that future dam operating rules need to closely mimic the natural hydrologic regime in order to maintain the biological dynamics of this and similarly diverse systems. In particular, high flows associated with increased catch the following year are important to maintain, but may be difficult to achieve in the context of reservoir regulation and energy production goals.

IntroduçãoA ocupação da Amazônia se deu ao longo de seus principais rios, e neste processo, se estabeleceram comunidades ribeirinhas, que podem ser classificadas como tradicionais (NASCIMENTO, 1996). A construção do modo de vida dessas comunidades é influenciada pela estreita relação com a natureza, seus recursos e o conhecimento aprofundado de seus ciclos (DIEGUES, 2000). Um dos principais recursos naturais explorados nestas comunidades é o peixe, tanto para subsistência quanto para comercialização (FISCHER et al, 1992). As pescarias de pequena escala, exercidas por 99% dos pescadores, são predominantes em áreas tropicais, e muitas vezes se localizam em pequenas comunidades que dependem de recursos locais (BERKES et al, 2006).A atividade pesqueira na Amazônia brasileira movimenta cerca de 400 milhões de reais (ALMEIDA et al, 2004), com o envolvimento de aproximadamente 368 mil pescadores e uma produção estimada em 166.477 toneladas (t) de pescado (MPA, 2010). Salienta-se ainda que a pesca comercial e a pesca de subsistência representam a maior fonte de geração de empregos do setor (McGRATH et al, 2004). Neste cenário,

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This work presents an indicators-based analysis of a small-scale fishery operating in the middle Madeira River (Brazil), a tributary of Amazon River. We used landing species (kg) recorded daily by the Porto Velho fishermen’s colony from 1990 to 2009, with total length recorded in five selected years. The species were classified by trophic level, and the Fishing-in-Balance, L index, and size class distributions were calculated. In addition, differences in yearly total landings (kg) were correlated with the Madeira river water level (cm). The average annual catch was 566.5 tonnes (± 193.6), with significant variation between the years not correlated to the river water level. The ecosystem indicators showed a stable tendency, with oscillations in the latter years reflecting an increased catch of higher trophic level and larger species. Fisheries managers in data-limited regions should consider these indicators for fish stock analyses to be low cost, practical, and easy to calculate.

RESUMOA pesca artesanal possui grande expressão socioeconômica na região Amazônica. Contudo há lacunas no conhecimento sobre a atividade em pequenos centros urbanos, especialmente em áreas de influência de empreendimentos. O estudo objetivou: avaliar e identificar características da pesca e comparar o esforço, custos e rendimentos da frota pesqueira do município de Humaitá, Amazonas. Analisou-se desembarques registrados pela Colônia de Pescadores e pela Universidade Federal de Rondônia, entre 2001 e 2013. A atividade é multiespecífica e praticada em pequenas embarcações, canoas (média 7,53 metros) e barcos de pesca (média 11,5 metros). A produção variou entre 178 t e 298 t, CPUE média mensal entre 10 e 43 kg pescador dia -1 e a renda mensal entre R$ 397,50 e R$ 2.375, para canoas motorizadas e barcos de pesca, respectivamente. Diferenças entre tipos de embarcações e características na atividade com outras regiões da bacia do rio Madeira reforçam a necessidade de monitoramento e estratégias de gestão diferenciadas.Palavras chave: atividade pesqueira; esforço de pesca; frota pesqueira; custos SMALL-SCALE FISHING AT HUMAITÀ MUNICIPALITY, MIDDLE MADEIRA RIVER, AMAZONAS, BRAZIL ABSTRACTThe artisanal fishing has socioeconomic expression in the Amazon region. There are gaps in knowledge about this activity in small urban centers, especially in areas with influence of projects. The study aimed to assess and identify the characteristics of this activity and compare the effort, costs and revenues of the fishing fleet in the municipality of Humaitá, Amazonas. We analyzed landings recorded by Colony of Fisheries and the Federal University of Rondônia, between 2001 and 2013. The fishing is multi-species and is practiced in small boats, canoes (mean 7.53 m) and fishing boats (mean 11.5m). The production varied between 178t and 298 t, monthly CPUE was 10 and 43 kg fisherman day -1 , and the income was R$ 397.50 and R$ 2.375 for motorized canoes and fishing boats, respectively. Differences between types of fleet and the characteristics in the activity compared to other regions of Madeira River Basin reinforce the need for monitoring and differentiated management strategies.

ResumoO presente estudo avaliou aspectos da pesca do pacu (Mylossoma spp., Myleus spp., Metynnis spp.) desembarcados no mercado pesqueiro Flutuante Cai N'água (Porto Velho, RO), no período de 1985 a 2004, verifi cando variações inter e intra-anuais da produção, variações nos comprimentos em centímetros e características gerais da pesca. A produção anual variou de 33.000kg a 146.000kg (média= 86.585kg), representando 6,63% a 20,45% do total das espécies desembarcadas no período estudado. Essas variações acompanharam o ciclo hidrológico, apresentando maior produção em anos subseqüentes às cheias intensas. A produção mensal variou de 0 a 42.366kg (média= 5.772kg) e esteve relacionada às migrações reprodutivas. O pacu apresentou oscilações de comprimento padrão de 14 a 20cm (18,72cm±3,69). A pesca foi baseada no uso de redes de lance e malhadeiras, onde os principais ambientes de captura foram os rios afl uentes do baixo rio Madeira (Jamari, Oropiara, Machado e Novo Aripuanã). A CPUE calculada entre os anos de 2003 e 2005 foi de 15kg.pescador -1 . dia -1 (±21). Os resultados mostram que a categoria constituiu no período um importante recurso para a exploração comercial local, como verifi cado para outras regiões da Amazônia. Abstract Pacu fi sh (Cuvier, 1818) (Characiformes: Characidae) landed in Porto Velho (Rondônia) fi sh market from 1985 to 2004. This study evaluated various aspects of the profi le of pacu (Mylossoma spp., Myleus spp., Metynnis spp.) fi sh marketed on the Cai N'água fl oating platform of Porto Velho (RO) from 1985 to 2004.Inter-and intra-annual variations in yield, variation in fi sh length and general characteristics of the fi shing are reported. The annual pacu yield ranged from 33,000kg to 146,000kg (average = 86,585kg), representing from 6.6% to 20.45% of the total landings in the studied period. These variations followed the hydrologic cycle, and the greatest yields were recorded in the years following the highest water levels. The monthly production ranged from 0 to 42,366kg (average = 5,772kg) and it was related to reproductive migration. The pacu presented variations in standard length from 14 to 20cm (18.72cm ± 3.69, mean ± sd). The fi shing was based on the use of seines and gill nets and the main environments of capture were tributaries of the low Madeira River (Jamari, Oropiara, Machado and Novo Aripuanã). The CPUE calculated for 2003 to 2005 was 15kg*fi sherman -C. R. C. Doria e M. A. Leite Lima 1 day -1 (sd = ±21). The results show that the category constituted during this period an important resource for local commercial exploitations, as verifi ed in other regions of the Amazon.

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ABSTRACT. The jatuarana (Brycon amazonicus), is an important species for the Madeira River commercial fisheries. The paper aims to characterize the jatuarana fishing dynamics in the middle Madeira River and test whether there are differences dowstreams and upstreams the Teotônio waterfall. Commercial fisheries landings were monitored daily at 15 ports or riverine communities along that stretch, using semistructured interviews with fishermen. With data from the fishing monitoring program of UHEs Santo Antônio and Jirau we analysed: the yield, catch per unit effort (CPUE), length structure, locations and fishing gear used, between 2009 to 2011.The fishing yield of this species was temporaly analyzed with data from the Fishermen Colony of Porto Velho city (Rondônia state, Brazil), between 1990 to 2012. The yield and the CPUE showed significant differences by area and locations and the capture of the species was carried out primarily in the channel river and banks river through gillnets. In addition, the samples collected in the upstream area have higher distribution and modal lengths than from those collected downstream. These results suggest that the areas require distinct management measures.