One of Earth’s biggest freshwater fish is bouncing back, a rare ‘win win’
The 10-foot-long arapaima was quickly disappearing in Brazil until local communities stepped in to save it—and themselves.
Giant freshwater fish are among the most endangered animals on Earth. But in the lush waterways of the Amazon, one leviathan is swimming against the current.
Meet the arapaima, a fish capable of growing up to 10 feet long and weighing up to 500 pounds. Just over a decade ago, this popular seafood species faced extinction, its numbers ravaged by overfishing. But conservation efforts spearheaded by local communities have turned things around for the arapaima, with populations increasing dramatically across the Amazon. (Read about efforts to save the world’s biggest freshwater fish.)
In areas where communities have adopted sustainable fishing practices, arapaima numbers increased 425 percent in 11 years, according to research by João Campos-Silva, a Brazilian ecologist and National Geographic Explorer. He is part of the National Geographic and Rolex Perpetual Planet Amazon Expedition—a two-year scientific exploration of the river basin. The number has since grown to 600 percent, though those results have not yet been published, he says.
To date, Campos-Silva has worked with around 40 communities along the Juruá River, a major Amazon tributary that traverses mostly pristine rainforest in western Brazil. Overall in the Amazon, around 1,100 communities have adopted conservation initiatives for the fish, which are listed as data deficient by the International Union for Conservation of Nature.
The arapaima’s resurgence is a conservation triumph that can serve as a blueprint for safeguarding other large aquatic species in the Amazon and globally, he says. And it highlights the crucial role of local communities in leading successful conservation endeavors.
“For many, many decades, people have been looking to the outside for solutions to the problems in the Amazon, but the arapaima story shows that the answers are often in the hands of the local people and communities living in the forest,” says Campos-Silva.
“They are the knowledge keepers.”
Trust the experts
Roughly the size of the contiguous United States, South America’s Amazon Basin, 60 percent of which lies within Brazil’s borders, is home to tens of millions of people, including around 400 Indigenous groups. The basin is crisscrossed by thousands of rivers with more fish species than in any other river system on Earth.
The largest scaled freshwater fish in the world, the arapaima in Brazil is known as the “pirarucu,” a word in the aboriginal Tupí language that translates to “red fish,” after its reddish tail. Prowling the region’s lakes and swamps, the predatory arapaima is an air breather that can only stay submerged for 10 to 20 minutes before resurfacing to breathe using a specialized, lung-like swim bladder.
This surfacing behavior makes arapaimas easy to catch. A 2014 study found their demand as seafood led to severe overfishing that depleted populations in three out of four of the fishing communities surveyed; the fish completely disappeared from a fifth.
By then, Brazil’s government had set up an extensive network of protected areas throughout the Amazon, with several states banning arapaima fishing. To better manage the species, scientists also developed a method to count arapaimas in their lake habitats, drawing inspiration from techniques used to survey breaching whales in the ocean.
The individuals most skilled at counting the fish were those who know them best: fishermen.
“In the split second that an arapaima comes to the surface, an experienced fisherman can tell you the size, weight, and direction of its movement,” says Leandro Castello, a tropical ecologist at Virginia Tech’s Global Change Center who helped develop the arapaima-counting model in collaboration with Instituto Mamirauá in Tefé, Brazil.
Conservation success
About 15 years ago, Campos-Silva, who initially worked on birds before turning his attention to Amazonian biodiversity, began working along the Juruá River, collaborating closely with the residents of the tight-knit São Raimundo community. He also supported the efforts of a local group called the Association of Rural Producers of Carauari to manage arapaima protected areas.
The São Raimundo community integrated their traditional knowledge with scientific methodologies, effectively making the conservation efforts their own, he says. “They had seen the decline in their fisheries and were eager to find solutions to improve the situation,” he says. (Read more about how scientists are saving megafishes.)
Based on fish counts, the community established a sustainable catch quota, with the federal government permitting an arapaima harvest of up to 30 percent of adults in protected areas. Fish under five feet long could not be harvested.
Most arapaimas spawn just after seasonal floodwaters rise and spread into the forest. When waters recede during the dry season, the fish are confined to isolated lakes and river channels. It's during this time that fishing operations are allowed.
The actions produced almost immediate results: Arapaima numbers, boosted by the species' exceptionally rapid growth rate, swiftly recovered.
As other Juruá River communities adopted the strategy, Campos-Silva was stunned by the economic and social benefits it yielded for local people. In addition to households making more money, improved fishing earnings were reinvested in local schools, health centers, and basic infrastructure. “People realized that through conservation, they can have a better life,” he says.
The community-driven initiatives have also enhanced the status of women, who, despite constituting nearly half of the global fisheries workforce, frequently go unacknowledged and unpaid. Women in the Brazilian Amazon are increasingly taking on roles aboard boats and participating more actively in decision-making processes, research shows.
“Our research shows that women are now for the first time earning their own money from Amazonian fishing, which is helping to eradicate general poverty,” says Campos-Silva.
In 2018, Campos-Silva founded Instituto Juruá, a Manaus-based nonprofit promoting biodiversity conservation and improved quality of life for local communities. He has since expanded his work to other parts of the Brazilian Amazon as well as the Ucayali River in Peru, another major tributary of the Amazon River with a large Indigenous population.
He and other scientists continue to gain deeper insights into the movement, ecology, and population dynamics of the arapaima, including through tagging and radio-tracking fish. For instance, they’ve found that for a population of arapaima to be deemed healthy, there should be a minimum of 30 individual fish per square kilometer of floodplain.
Arapaima in Guyana
The community-based conservation approach has yielded even more spectacular results in Guyana, with arapaima populations there increasing tenfold since the turn of the millennium, says Donald Stewart, a fisheries professor at State University of New York.
Yet there are still many unmanaged areas of the Amazon where arapaimas may be going locally extinct. “Vast areas still don’t have rigorous population counts or local engagement to protect the fishes from outsiders,” he says.
Stewart believes the arapaima could be the largest freshwater fish on Earth. Studying growth ring deposition on the scales of arapaimas living in Guyana’s Essequibo River have shown those animals may grow much heavier than those from central Brazil, Stewart says. His research has shown there are several more distinct species of arapaimas, and some could still be considered critically endangered. (Read about a new arapaima species announced in 2016.)
Unmanaged movements of arapaima around Brazil could lead to disease transfer and genetic mixing among these potentially distinct populations, issues that remain largely unstudied.
For Zeb Hogan, a biology professor at the University of Nevada, Reno, and a National Geographic Explorer, the arapaima conservation success can be a model for protecting and managing populations of other endangered giant fish around the world.
“These results buck an otherwise gloomy trend of severe decline of most species of aquatic megafauna,” he says. “It’s a rare example of a win-win solution that can be replicated in many areas worldwide.”
Look for more reports from our Amazon expedition in coming months, including a special issue this fall. We’ll also launch an immersive digital experience at natgeo.com in September, and a documentary will premiere October 10 on National Geographic and stream on Disney+ and Hulu.
