Componentes da paisagem e o rendimento pesqueiro na várzea amazônica

Abstract

The areas periodically flooded by white water rivers represent a large part of the humid areas of the Amazon, being one of the main components that sustain fishing and other activities in the region. In these flood plains, there are lowland lakes, areas with high proportions of fisheries and different landscape components that vary in time according to the flood pulse and spatially according to aspects of human use / occupation and geomorphic context. These differences imply the existence of an East-West gradient in the structure and composition of the landscape components between the regions of the Lower Amazonas and the Lower Solimões in the Central Amazon. Here, we aim to evaluate the relationships between landscape components and the fishing yield in floodplain lakes in these two regions and possible patterns resulting from differences in the characteristics of the fishing areas. We quantified landscape components data considering buffers of 1000 and 2000 m around the open area of the lakes during the dry season and correlated it with the fishing yield of the commercial fleet in the municipalities of Alenquer (Baixo Amazonas) and Manacapuru (Baixo Solimões). We found differences between the landscape components of the floodplain lakes and that such differences depend on the scale and the seasonal period analyzed, with a predominance of flooded herbaceous in the further downstream portion in both periods and, flooded shrubs and forests upstream in high waters in the greater scale. The local factor was consistently the variable of greatest relative importance (Σwi> 0.9), indicating that the region of the Lower Amazonas has lower fishing yields when compared to the Lower Solimões. Shrubs flooded on the smallest scale were the landscape component most correlated with higher fishing yields independent of the region. The observed increase in fishing yield with the increase in flooded shrub cover, may reflect the lateral migration of several species to these flooded habitats for breeding, feeding and / or refuge. The difference in fishing income between the two regions, which is not explained by the extent of the landscape components, may be due to the local context of exploitation of fishing resources in the Lower Amazon region, which has historically undergone high fishing efforts under the floodplain lakes. We highlight the importance of flooded shrubs even in threshold situations, supporting the idea that the loss of this structure can cause a reduction in fishing yield per unit of effort.