A pesca de subsistência e comercial na Amazônia brasileira

Abstract

Subsistence and commercial fisheries are of high social and economic importance in the Amazon Basin. However, catches are underestimated and are largely vulnerable to impacts on aquatic ecosystems from human actions. Considering this, in this thesis the contribution of subsistence fisheries to the total catches of the Amazon basin was estimated, and the spatial dynamics of fisheries were evaluated based on the composition of commercial catches, landscape dynamics and the river level. In chapter one, the subsistence fishery catch was estimated using demographic data from the Instituto Brasileiro de Geografia e Estatística (IBGE), an Amazonian wetland mask, and per capita fish consumption rates from the literature. The number of people in wetlands was extracted from IBGE data clippings on the wetland mask. Fish consumption rates were interpolated for the Amazon region using the Inverse Distance Weighted (IDW). Subsequently, the product between the number of people in wetlands and the interpolated fish consumption rates was performed. The result was considered as the subsistence fisheries catch and was divided by level four sub-basin for regional assessment. An estimated 1,732,659 people were in wetlands. Per capita fish consumption rates ranged from 51 kg/year to 266 kg/year. The catch from subsistence fisheries was estimated at 190,686 t/y, which is higher than some estimates from commercial fisheries. The highest captures were observed in regions of white-water rivers. In chapter two, the spatial dynamics of fishing was evaluated using fish landing data from the Upper and Lower Solimões and Lower Amazon Rivers, and available river and landscape variables databases. Maps of the fishing fleet's operating range were prepared, and the landscape variables were quantified by region and flood period. The assessment of catches by species, by region and hydrological period was performed using non-metric multidimensional scaling (nMDS) analysis. The largest radius of activity of the fishing fleet was identified in the Lower Amazon River. The proportion of landscape variables varied along the river channel and between periods of flooding. The diversity in the composition of landings between the three regions analyzed possibly varied with the availability of habitats, indicating the importance of landscape variables for the fishery resources that are captured.