Community-led conservation efforts in Brazil’s western Amazon are delivering ecological benefits far beyond their immediate targets, but at a significant cost to the families who sustain them, a new study published in Nature Sustainability has found.
Along the Juruá River, one of the most winding tributaries of the Amazon, fishing communities have taken responsibility for protecting pirarucu, one of the world’s largest freshwater fish species. By guarding oxbow lakes from illegal fishing, these communities are not only reviving a species once close to extinction but also safeguarding vast stretches of floodplain and upland forest ecosystems.
Conservation footprint extends far beyond guarded lakes
The study shows that community patrols covering 96 oxbow lakes across 14 rural communities effectively protect an area nearly 86 times larger than the lakes themselves. While the lakes are the focal point of conservation, access restrictions prevent poaching across adjoining floodplains and indirectly shield upland forests as well.
Researchers found that during the dry season, when pirarucu gather in shrinking water bodies, surveillance intensifies. During the monsoon, when fish migrate into flooded forests, protection expands naturally to wider landscapes. This interconnected safeguarding of aquatic and terrestrial ecosystems makes it the largest community-based conservation initiative currently documented in the Brazilian Amazon.
Scientists say the findings highlight how local stewardship can strengthen ecological connectivity across ecosystems, challenging the assumption that conservation impact is limited to formally protected zones.
Revival of pirarucu reshapes ecosystems and livelihoods
The pirarucu plays a central ecological and cultural role in Amazonian floodplains. As an apex predator, it helps regulate aquatic food webs, and its presence is associated with higher biodiversity in lakes and flooded forests. According to the study, community-led management has helped increase pirarucu populations by over 400% since the early 2000s.
Traditional ecological knowledge has been critical to this recovery. Local fishers use ancestral counting methods based on the fish’s need to surface for air, allowing accurate population estimates without invasive techniques. Controlled harvesting has also become a major income source, with proceeds reinvested into healthcare access, infrastructure and community welfare.
Researchers note that this blend of conservation and livelihood security demonstrates how biodiversity protection can align with social development when communities retain decision-making power.
Economic burden threatens long-term sustainability
Despite its success, the conservation model places heavy financial pressure on participating families. The study estimates that surveillance alone accounts for nearly one-third of total management costs, reducing household incomes by around 21%. Guards patrol without wages, absorb food and equipment expenses, and face safety risks from confrontations with poachers.
If labor were formally compensated, conservation costs would increase several-fold, highlighting the gap between ecological value and financial support. Researchers argue that without external funding, such models risk burnout and long-term collapse.
To address this, the study recommends payments for environmental services, where communities are directly compensated for protecting ecosystems that deliver regional and global benefits. Discussions around pilot payment programmes were held during climate negotiations ahead of COP30 in Brazil, signaling potential policy movement.
The research also notes growing participation of women and youth in fisheries management, improving gender equity and reducing rural migration. Scientists conclude that while community conservation has proven its ecological power, sustained success will depend on recognising and rewarding the people bearing the cost of protecting the Amazon.