SYMP 20-3 - Fishers' local ecological knowledge contributions to ecological science in tropical small-scale fisheries

Fishes in biodiversity rich-aquatic ecosystems have multiple trophic interactions, which provide ecosystems services, but can be affected by fisheries and environmental changes. The small-scale fisheries in developing countries, such as in Brazil, provide employment, food and income to millions of people. Fishers rely on multiple fish species, which usually lack scientific data. However, the fishers from local communities have a rich local ecological knowledge (LEK), which can fill gaps, improve understanding and inspire new hypotheses on fish ecology and its relation to fisheries. We provide an overview of results from studies that have successfully applied fishers’ LEK and ecological analyses as complementary sources of information to better understand fish trophic ecology in Brazil. The methods involve simple standardized individual interviews with fishers, aimed at collecting quantitative data, whereas not taking much time from the interviewees. Although being a more rapid appraisal, this approach allowed our research team to assemble and compare data from fishers’ LEK from several sites, which were useful to elaborate conceptual models and employ ecological analyses. Information provided by fishers about what a fish eats and which animals eat the fish could be organized in conceptual models of aquatic food webs in a coastal island and in an Amazonian river. A compilation of studies addressing fishers’ knowledge on diet of over 60 coastal and freshwater fish species allowed us to calculate fish trophic levels based on data from interviews with fishers. These trophic levels were positively correlated to fish trophic levels from the biological literature and to concentrations of mercury (Hg) in fish tissue. In another research, trophic levels of six fish species based on fishers’ LEK closely matched values of trophic levels calculated through stable isotope analyses of the same species in two Amazonian rivers. Finally, a survey based on interviews with 418 fishers in 24 communities in three Amazonian rivers revealed that six herbivorous fish species can eat 92 plant species, including potential seed dispersal in some of these fish and plant interactions. These interactions between fish and plants based on fishers’ LEK were analyzed through ecological interaction networks. We show here that fishers’ LEK can considerably advance the ecological knowledge and its contributions to fisheries management or impact assessment. We hope that, by showing the value and applications of fishers’ LEK, our work can promote the inclusion of these fishers in political and management decisions regarding the fisheries and related aquatic ecosystems.