Avaliação do efeito da pesca nos estoques pesqueiros da Amazônia Central

Abstract

Commercial fishing is a large extractive activity used in the Amazon, influenced by the regional culture, economy and its characteristic seasonal periods. In the 40s, fishing in the Amazon was performed by a primitive fleet of boats, then in the 50s to 70s comercial fishing became efficient in relation to fish catching, this was made possible by the development of the industrial sector and modernization of vessels and fishing gear. The development of comercial fishing in the Amazon resulted in overexploitation of the fishing resources, mainly in the top demanded species of market. Some studies describing the dynamics of local fishing were made in cities in the Amazonas state. Even though these studies contributed with fishing information, there is some lack of detailed information, specifically on physical characteristics, quantification and distribution of the fishing fleet, mainly in Manaus, the most important city for comercial fishing landings in the Amazon region. In this work, it was described the fleet that landed fish in Manaus, comparing information available in the scientific literature for 44 years, to verify changes in the fishing power of the vessels and dynamics of the fish species caught. It has been shown that the vessels have changed in size and there has been a breadth of engine power over the past five decades. Also, there was an increase in the number of boats until 2004, and after that, there is no information on the number of boats, due to the lack of data collected. Nevertheless, the appearance of the glacier was recorded, being used in an altering way to store the fish, but with that, there was a reduction in the average storage capacity on the vessels As of 1996, the tambaqui, which was the main species most landed in the 1970s, suffered a sharp decline in their production, as a result, migratory characiforms such as jaraqui and curimatã rose as the most landed fish in recent years.. Other results did not change, following the pattern of behavior of the last five decades, with the net and gillnet being the main fishing equipment used, and the second half being the period with the highest production of fishing, and the one with the lowest production being occurring in the first semester, with the Solimões and Purus rivers being the most commercially exploited for fishing. In the final part of this study, the impact of artisanal fishing on the structure of fish communities in Central Amazonia was examined, showing what are the possible changes in the average trophic level of fishing landings and in the ecological balance index caused by fishing activity in the past 44 years old, due to the application of ecological indicators Average Trophic Level of landings and Fishing in Balance Index (FiB - Index). Using the two indicators, it is possible to demonstrate that the pressure caused by fishing stocks in the Amazon is directed to different trophic levels, where four levels can be specified, detritivores, omnivores, herbivores and piscivores, even so “fishing down food web” effect has not been seen, more observed sea fisheries. Therefore, it is seen that the evaluation of fish stocks landed in tropical freshwater systems, composed of the trophic level indicator and balanced fishing index, can be low cost and efficient strategy, in relation to the high diversity of species and the absence of continuous fisheries statistics systems for management in the Amazon basin.