Length-weight relationship (LWR) is likely the most useful tool to estimate indirect growth, body condition, and to understand the life cycle of fishes (Camara, Caramaschi, & Petry, 2011; Froese, 2006). Length and weight are biometrics data easily taken and available in most datasets from monitoring studies. Despite the simplicity, it provides highly useful information for fisheries management and can be used in different applications like the estimation of biomass from length data or comparisons between growth patterns and morphologic differentiation of the same species from different populations (Imorou, Alphonse, Edmond, & Youssouf, 2019; Karachle & Stergiou, 2012). The Amazon basin shelters a very highly diverse freshwater fish fauna that occupy a wide variety of environments. The middle stretch of the Amazon River sustains very important fishery activities, which targets about 100 species coming from its main channel and associated floodplain environments (Santos, Ferreira, & Zuanon, 2006). Here we present LWRs for 39 fish species based on 18 years of monthly fish sampling in the Catalão Lake, at the confluence of Amazonas and Negro rivers.

Despite the high number of fish species described for the Amazon region, the ichthyofauna that inhabits the depths of the main channels of large tropical rivers is one of the least known. In order to know the diversity patterns of these fish in whitewater rivers of the Central Amazon, we used data from the main channel benthic fish assemblage of the Japurá, Purus and Madeira rivers and tested the hypothesis that there are marked spatial and seasonal differences in the composition of the fish community among them. For this, we used a multivariate dispersion test, total β diversity and its decomposition into local (LCBD) and species contribution to β diversity (SCBD). Additionally, we tested for relationships between LCBD values and richness, total abundance, and environmental variables. We categorized species with higher SCBD values into resident or migratory to investigate the potential importance of floodplains to benthic fish assemblage of the main channel of whitewater rivers. Our results corroborate the proposed hypothesis, showing that there are seasonal and inter-river differences in benthic ichthyofauna, being more evident for the Purus River. LCBD showed strong negative relationships with species richness and total abundance, particularly in the Japurá and Madeira rivers in rising season, indicating that rivers and season with high uniqueness in their composition also had low richness and abundance. LCBD was negatively correlated with conductivity and pH, which increased with declining these environmental variables, as observed mainly in Japurá River in both seasons. Approximately one third of the species had higher than average SCBD values and were considered major contributors to β diversity, as well as classified as migratory. This demonstrates the importance of conducting studies that use spatial and seasonal variables, in addition to including the background fish fauna in conservation studies, expanding the protected area and taking into account the different patterns of diversity between rivers. Furthermore, these differences in assemblage composition might be explained by the asymmetrical spatial use of habitats during different seasons, strongly suggesting the importance of the flood-pulse cycle for maintaining diversity in this environment.

Abstract. Differences in food intake and morphological attributes may facilitate the coexistence of detritivorous fish. The present study investigated the possible differences in the feeding strategies of four species of curimatids that inhabit the floodplain of the central Amazon. For this, we determined the diet, daily food cycle, and whether characteristics of the intestine were related to the length of the fish and the amount of detritus consumed. The detritivory was confirmed, and we observed a difference in the foraging time between species. We found differences in the length and weight of the intestine and the relationship of these variables with the length of the fish and the amount of detritus consumed. Our study suggests that despite belonging to the same family and food group, curimatids have characteristics that allow them to consume the detritus in different ways.

Lorem ipsum dolor sit amet. Qui quam enim id sunt incidunt At eius assumenda eos voluptas culpa hic eius molestiae Nam consequatur quam rem delectus mollitia qui commodi suscipit. Est ipsa omnis sit dolor voluptates ut ration omnis non dignissimos doloremque est doloribus ipsa non neque tenetur.Lorem ipsum dolor sit amet. Qui quam enim id sunt incidunt At eius assumenda eos voluptas culpa hic eius molestiae. Lorem ipsum dolor sit amet. Qui quam enim id sunt incidunt At eius assumenda eos voluptas culpa hic eius molestiae. Nam consequatur quam rem delectu mollitia qui commodi suscipit. Est ipsa omnis sit dolor voluptates ut ratione omnis non dignissimos doloremque es doloribus ipsa non neque tenetur.Lorem ipsum dolor sit amet. Qui quam enim id sunt incidunt At eius assumenda eo voluptas culpa hic eius molestiae.

A geração de conhecimentos voltados para o manejo de recursos naturais é fundamental para estabelecer estratégias de conservação da biodiversidade. Neste sentido, iniciativas de pesquisa, monitoramento, integração de conhecimento científico e empírico, com objetivos de conservação da ictiofauna estão sendo realizadas na Reserva Biológica do Abufari (Rebio do Abufari). Os resultados dessas iniciativas poderão subsidiar gestores e comunidades no manejo e estabelecimento de um Termo de Compromisso que minimize conflitos gerados pelo uso de recursos pesqueiros por populações tradicionais em uma unidade de conservação (UC) de uso direto. Um Diagnóstico Pesqueiro foi elaborado com a finalidade de caracterizar a pesca e sua importância na Rebio. Paralelamente, foi implementado um protocolo de Automonitoramento da Pesca, como parte do Subprograma Aquático Continental do Programa Monitora do ICMBio, em parceria com o Instituto de Pesquisas Ecológicas, para observar mudanças na atividade ao longo do tempo. Além disso, a UC integra o Programa de Pesquisa Ecológica de Longa Duração – Diversidade de peixes na várzea amazônica (PELD DIVA-CNPq), coordenado pelo Instituto Nacional de Pesquisas da Amazônia, que visa produzir conhecimento sobre diversidade ictiofaunística e estoques pesqueiros em áreas de várzeas e descobrir como as comunidades de peixes reagem às diferentes ações de manejo e mudanças climáticas. Para promover o diálogo sobre os resultados das iniciativas entre os atores envolvidos, foi realizado em 2020 o primeiro Encontro dos Saberes na Rebio. Neste artigo descreveremos as atividades realizadas e principais resultados, visando a subsidiar a elaboração do Termo de Compromisso e estabelecer estratégias de conservação da ictiofauna que possam minimizar conflitos de interesses entre os diferentes atores.