- In Brazil’s western Amazon, community-led efforts to protect the pirarucu, one of the world’s largest freshwater fish, bring conservation benefits that extend into upland ecosystems.
- A study in Nature Sustainability found that by patrolling oxbow lakes along the Juruá River, communities effectively protect a mean area 86 times larger than the lakes they directly monitor, making this the largest community-based conservation initiative in the Brazilian Amazon.
- Local families bear the full economic burden of conservation efforts; surveillance represents 32% of total costs and reduces community income by 21%. Researchers say that using payments for environmental services would help ease pressure on communities.
In rural communities living near Brazil’s Juruá River, a tributary of the Amazon River that flows northward through the country, families of fishers take turns in guarding the entrances of oxbow lakes. The most sinuous river in the Amazon Basin, the Juruá, meanders through low-lying floodplains, creating numerous stagnant water bodies. From small wooden watchtowers built on the water, the community members watch for poachers who seek to illegally harvest pirarucu (Arapaima gigas), the largest freshwater fish species in the Amazon and a staple species for communities’ food security.
A study published in Nature Sustainability found that these community-based conservation efforts benefit not only pirarucu and oxbow lakes, but also connect floodplain and upland ecosystems. By limiting access to outsiders, confiscating poaching equipment and reporting illegal activity to government agencies, community members effectively protect natural resources and their own livelihoods. However, this work comes at a substantial cost, researchers found. While on patrol, guards cover the expenses of surveillance, spend days away from their jobs and risk dangerous encounters with poachers, all without pay.
A broader conservation footprint
Community-based conservation is a strategy that places local communities at the center of managing and protecting natural resources, rather than excluding them. While it involves collaboration among community members, researchers and government agencies, its success comes from local knowledge and community-driven collective action. Conservation goals prioritize the protection of both biodiversity and local livelihoods.
To understand the scope of protections provided by the co-management of pirarucu in the Brazilian Amazon, the researchers looked at the largest community-based fisheries conservation initiative in the Basin. They focused on 14 rural communities that monitored a total of 96 oxbow lakes along the Juruá River, with individual communities having as many as 13 lakes in their jurisdiction. While monitoring took place year-round, patrols intensified during the dry season, when river levels drop and pirarucu concentrate in oxbow lakes.
The study found that by patrolling the lakes, community members were effectively protecting a floodplain area nearly eight times larger than the lakes themselves. When taking into account that pirarucu move into inundated floodplain forests during the rainy season, researchers found that each community protected an area 36 times larger than the lakes. Cutting access to floodplains also provided indirect protection to upland forests on an area roughly 40 times larger than the total size of the protected lakes. The study found that by putting all these protections together, each community conserved a mean area of floodplain and upland forest that was almost 86 times larger than the lakes alone, the researchers found.
For co-author Ana Carla Rodrigues, the research highlights how community-based conservation can strengthen ecological connectivity. “Initial evidence suggests that community protection of aquatic environments for pirarucu management generates positive ecological effects that extend to terrestrial ecosystems,” she wrote in an email to Mongabay. According to Rodrigues, this example shows that community-led conservation is viable, effective and socially transformative, giving local communities agency in natural resource management.
“To build a brighter future for the Amazon, we need to have conventional science and traditional knowledge together at the same table,” João Campos-Silva, study co-author and researcher at the Juruá Institute, an NGO that supports community-based initiatives, told Mongabay in a phone interview. “Community conservation is a window to learn from Indigenous people and implement changes for a better world.”
The pirarucu: An ecological and cultural anchor
According to Lesley de Souza, an ichthyologist and conservation biologist who studies pirarucu in Guyana, the species at the center of these conservation efforts has a tremendous influence on floodplain ecosystems. “Pirarucu are omnivorous, and they’re important because of all the cascading effects they have on the food chain,” she told Mongabay in a phone interview. “Some people call them ‘the mother of all fish.’ They’re very old, and they’re sacred in some communities.”
For de Souza, part of what makes pirarucu special is its evolutionary past. “Their ancestors are related to fish that were around with the dinosaurs,” de Souza said, noting that the species’ physiology reflects adaptations preserved across millions of years. Lakes with pirarucu are also noticeably more biodiverse. “Any pond that has arapaima seems to have a suite of different species,” she said.
Their presence shapes entire aquatic communities, de Souza said. Apex predators that can reach up to 3 meters [9.8 feet] in length and several hundred pounds, pirarucu fill a critical ecological niche that helps structure food webs and stabilize ecosystem dynamics. Their seasonal movements through lakes, rivers and flooded forests depend on intact floodplain ecosystems, making healthy forests essential to their life cycle.
In the Brazilian Amazon, community stewardship along the Juruá River has brought pirarucu back from near extinction, helping to increase its population by 425% since the early 2000s. According to Rodrigues, traditional ecological knowledge has been key to this recovery. “Because pirarucu must surface to breathe, fishers developed ancestral counting practices that read the rhythm of the water and the animals’ behaviour,” she wrote. This finely tuned perception is central to reliably estimating fish numbers, she explained.
Income from controlled pirarucu harvests has become increasingly important for community well-being. Rodrigues told Mongabay that a portion of the annual revenue is reinvested back into the community, in things like infrastructure improvements and support for people who need to travel to see a doctor. In her view, these investments reinforce the shared value of community-based management.
The cost of protection
The families preserving pirarucu bear the full cost of their conservation work, the study showed. Although people volunteer to patrol and monitor the region, they need money for food and supplies. Surveillance expenses represent about 32% of the total costs of managing the fisheries and cut the community’s income by about 21%. The study estimated the average cost of protecting the lakes at $0.95/hectare/year, a substantial expense for low-income communities in the Amazon. If labor were rewarded, the costs for effectively protecting the land would increase to $5.30/hectare/year in a scenario where two guards are paid local daily wages, or $5.40/hectare/year if paid Brazil’s minimum wage.
Researchers say that costs could be covered by payments for environmental services (PES) that directly compensate communities for protecting these ecosystems and their services. Rodriguez told Mongabay that in 2025 at COP30 in Belém, Brazil’s Ministry of Environment and Climate Change discussed a pilot PES initiative that would test payment distribution on a small scale before a larger national rollout. Under this framework, communities would continue to provide these ecosystem services, while local associations would manage and distribute funds.
According to Campos-Silva, funding to support community-based conservation efforts like the pirarucu co-management could come from specific government departments. It could also come from organizations like the Tropical Forests Forever Facility, a large-scale financing initiative that protects tropical forests through public and private investments. Both he and Rodrigues emphasized that any PES model must prioritize transparency, accountability and social justice to ensure equitable distribution and long-term sustainability.
Conservation brings more gender equity
Responsibility for managing the fisheries is shared across households and increasingly across genders. While gender roles were not a focus of this study, Rodrigues noted that women’s roles in fisheries management have historically been overlooked, even though they’ve always been involved in surveillance. However, community management has increased the visibility of their contributions. “Today, [women] have mastered techniques once restricted to men, such as counting pirarucu, one of the essential stages of management,” she explained. “They also participate in decision-making and leadership roles within community associations.”
Campos-Silva added that women have gained autonomy, empowerment and income through pirarucu management. Younger community members are involved in fisheries management as well, a shift that is helping to reverse migration of young people toward cities.
“For a very long time, conservation science excluded local people,” Campos-Silva told Mongabay. “Now, it’s clear there is no future for the Amazon that doesn’t come from local hands.” He said shifting to a system that directly funds the people doing the work is essential. “Local people are the most important part of the solution to protect the Amazon, and they should be recognized and rewarded,” he said. “We need a mechanism that can give them financial returns and ensure dignity at the frontlines, because they’re ensuring environmental services that are very important for our society.”
Banner image: Pirarucu on a boat on the Juruá River. Image courtesy of João Campos-Silva.
Citations:
Rodrigues, A. C., Costa, H. C. M., Peres, C. A., Brondizio, E. S., Dias, A., De Moraes, J. A., De Araujo Lima Constantino, P., Ladle, R. J., Malhado, A. C. M., & Campos-Silva, J. V. (2025). Community-based management expands ecosystem protection footprint in Amazonian forests. Nature Sustainability, 8(11), 1304–1313. https://doi.org/10.1038/s41893-025-01633-6
Fariss, B., DeMello, N., Powlen, K. A., Latimer, C. E., Masuda, Y., & Kennedy, C. M. (2022). Catalyzing success in community-based conservation. Conservation Biology, 37(1), e13973. https://doi.org/10.1111/cobi.13973
Campos‐Silva, J. V., Hawes, J. E., & Peres, C. A. (2019). Population recovery, seasonal site fidelity, and daily activity of pirarucu (Arapaima spp.) in an Amazonian floodplain mosaic. Freshwater Biology, 64(7), 1255–1264. https://doi.org/10.1111/fwb.13301
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