When predators become prey: Community-based monitoring of caiman and dolphin hunting for the catfish fishery and the broader implications on Amazonian human-natural systems

Wildlife hunting for commercial products has been responsible for decline of many large vertebrates around the globe. An Amazonian example of this worldwide trend is the use of caiman and dolphins as bait for the piracatinga catfish fishery. While it is a controversial issue in Amazonia conservation, there is no data on key biological aspects, such as age and sex, of those animals illegally hunted for bait. This lack of data complicates understanding of the true impact of bait-hunting on the targeted species. In this study, we present results of one year of participatory monitoring of bait-hunting in 12 communities in the Mamirauá Sustainable Development Reserve (MSDR), Brazilian Amazonia, during which participants recorded aspects of hunting activity and biometric data of animals used as piracatinga bait. The piracatinga fishery at MSDR has distinct spatial and seasonal patterns, being concentrated close to distribution centers and intensifying during the dry season. Adult male black caiman is the main bait used by fishermen, but viscera of commercial fish provide a potential alternative bait source for the piracatinga fishery. All recorded bait hunting was for caiman, none for dolphins. Despite the predominant use of caiman as bait, MSDR caiman populations remain the largest within the species' distribution. We suggest that informal management of caiman conducted by MSDR residents has guaranteed regional sustainability of the piracatinga fishery. In a broader context, the current study highlights the potential for participatory research with local populations in formulating well-informed decisions for the conservation of natural resources and economic alternatives focused on the conservation of human-natural systems.