Condicionantes ambientais e sua relação com a pesca artesanal nos estuários dos rios Choró e Curu, estado do Ceará

Abstract

The state of Ceará counts up to twenty estuaries within its territory. Local communities settled down around the estuaries, using them to develop artisanal fishing activities. Artisanal fishing represents an ancient job, whose origins can be traced back to the origins of humanity. Artisanal fishermen own a precious knowledge of both the physical characteristics of the place where they work and the environmental conditioning factors that determine fishes distribution and capture techniques. Thus, artisanal fishermen’ ecological knowledge represents a fundamental tool to elaborate useful environmental management plans. The present work aims to describe how local oceanographic features, such as tide, salinity, wind and coastal current influence both fish species occurrence and artisanal fishermen recruiting in Rio Choro and Rio Curu estuaries throughout the whole year. Rio Choro’s and Rio Curu’s estuary are situated respectively in the eastern and in the western coast of Ceará State (Brazil). Semi-structured questionnaires have been submitted to artisanal fishermen of both the estuaries, in order to characterize the regions and explore their fishery resources through fishermen’ traditional ecological knowledge. Moreover, in order to reinforce questionnaires results and to analyze the relation in between the environmental feature of salinity and the distribution of the principal commercial fish species, experimental fisheries and salinity measurements have been done in the same fishing areas used by the interviewed fishermen (identified in this work as Zone 1, 2 and 3). The results show that, firstly, artisanal fisheries take place mainly near the habitations of fishermen. Secondly, it resulted that, on the one hand, the environmental features analyzed in the present study do not influence the occurrence of the main commercial fish species (Taínha, Carapeba, Bagre e Camurim) of the two estuaries, except for salinity, which proved to be a significant condition for the presence or absence of some of these species. On the other hand, the four environmental features demonstrated to strongly influence estuarine artisanal fishermen activity. In conclusion, conditions of low tide favour fish recruiting with lower efforts, while winds and currents promote respectively an easier handling of fishermen’s equipment and a larger entrance of sea fish species in the estuary. Salinity does not influence artisanal fishermen’s choice of fishery areas. However, high salinity values are correlated with a lower abundance of the main commercial fish species analyzed in the present study.