Sustentabilidade ecológica e econômica da pesca comercial do município de Barcelos, Região do Médio Rio Negro, Amazonas

Abstract

Studies on fishing activities in the Amazon region are facing trough the Solimões-Amazonas, however little is known about commercial fishing in black water rivers. Thus, considering the lack of data in the region of the Middle Negro River this study was to assess the sustainability of commercial fishing in the municipality of Barcelos, by characterizing the fleet landing analysis and modeling ecosystem of fishing activity. Information on the physical, operational and economic features were collected through structured questionnaires from February 2012 to January 2013, with the fishermen of fishing boats and motorized canoes. Overall, commercial fishing is the main economic activity, but they also participate in other activities, mainly related to sport and ornamental fishing. The physical characteristics of the vessels are similar to those of other regions studied in the Amazon. The fishing boats are the primary storage facilities for fish landings. Gillnets were the main gear used by fishermen. Fuel was the greatest expense associated with fishing. 56.0 tons of fish were landed, with the average values of landing 3.6 (± 2.2 t/month) and 1.1 (± 0.7 t/month) tons per month for the larger-boats and the small boats with outboard motors respectively. Pacu (Subfamily Myleinae), aracu (Family Anastomidae) and tucunaré (Cichla spp.) were the main species caught, responsible for approximately 50% of the landings. The Demeni River, Anauali Lake and Zamula stream fishing sites were more exploited. It was evident that the boats exploited the lakes in dry and flood seasons, while the rivers were explored in all seasons of the hydrological cycle, with a slight predominance of outflow season. The streams were also exploited in all seasons, with the exception of the flood. In regards to small motor boats, lakes remained the preferred environments in the dry season. While the rivers were explored throughout the year. The streams were operated mainly in the outflow and flow seasons. The vessels showed a decrease in fishing effort in the flood and dry season increased, with average CPUE of 21.9 and 23.9 kg/fisherman*day for boats and canoes respectively. Four scenarios were simulated to verify the behavior of the stock front to drastic changes in the system, which comprised the following variations: a) Scenario I: increased rates of fishing mortality of Characiformes, Siluriformes and Perciformes (b) Scenario II: reduction in the rate of replenishment of stock, (c) Scenario III: 50% reduction in fishing mortality rates, and (d) Scenario IV: analyzed the effect of the combination of the scenarios I, II and increased total costs and price per kilogram of fish. The planning horizon utilized was 70 years. Scenario III proved to be the most sustainable use of fishery resources as the conditions used in this simulation the stock remained in place for well over 70 years. Given this optimistic scenario, it would be interesting as a management measure for the region, had effective control of fishing access. Where users can be aware and take into account that these natural resources, even though renewable, are also liable to exhaustion. Key words: commercial fishing, Barcelos, costs, system dynamics, sustainability, ecosystem models