Carine Emer, Miguel Lurgi, Sérgio Timóteo, João Vitor Campos-Silva, Shai Pilosof 

Global demand for natural resources challenges the sustainability of small-scale fisheries. Fisheries Co-Management (FCM), where management is shared between the government and locals, is crucial for maintaining viable fish populations while mitigating market pressures and illegal fishing. Using a data-informed model applied to a fish metapopulation network, we contrasted the effects of various FCM scenarios on the abundance of Arapaima (Arapaima gigas) populations—a key income source for Amazonian communities—across 13 protected and 18 unprotected lakes in the Juruá River Basin, Brazilian Amazon. Our results show that the current FCM scheme is suboptimal and could be improved by protecting lakes based on their carrying capacity, which enhances population resilience in protected lakes and maintains stocks in unprotected ones. Lakes interconnectivity also plays a key role in sustaining regional metapopulation dynamics. Expanding FCM practices across the Amazon requires integrating local knowledge with scientific evidence to support biodiversity and local well-being.