Indigenous people and scientists unite to track giant dam’s environmental toll

_SCIENCE

Soon after sunrise one warm day in September 2022, 26-year-old Josiel Pereira Juruna boards a small motorboat and sets out on the emerald-green waters of the Xingu River in the Brazilian Amazon. Accompanying him are biologist Cristiane Carneiro and Pedrinho Viana, a fellow fisherman from their village of Muratu in the Paquiçamba Indigenous Reserve in northern Brazil’s Pará state. After a short ride, Viana hauls in a gillnet set out in a creek the night before.

He pulls a disk-shaped fish with bright gray scales and a yellowish belly from the net and hands it to Josiel, who hangs it from a portable scale. “One hundred and fifty grams,” he declares, then presses a ruler against the animal, known as a big-eyed pacu. “Fifteen centimeters,” he says, as Carneiro takes notes.

It’s a ritual of weighing and measuring that Josiel has performed nearly daily for the past 3 years to monitor the river’s fish stocks. Of all fish in this stretch of the Xingu, the seven species of pacu are the most important for his community, the Juruna, who rely on fishing for food and income. Known as vegetarian piranhas, pacu can reach up to 1 meter long. But they are dwindling. In November and December 2014, the best fishing months of that year, fishermen in Muratu caught a total of 770 kilograms of pacu. Over the same months in 2021, that number dropped to 175 kilograms.

“Now we only catch very skinny and small pacu, almost without fat,” Josiel says with disappointment as he gestures to the specimen in his hand.

The likely cause lies 30 kilometers upstream of Muratu: the largest hydroelectric project in the Amazon basin, a complex of dams, reservoirs, and power stations known as Belo Monte. The project was originally slated for construction in 1975, but years of protests from Indigenous communities and a lack of investment stalled it. In the 2000s, after major electricity blackouts in the country, President Luiz Inácio “Lula” da Silva (recently reelected) pushed for the project, despite international opposition from environmentalists and scientists, and it began operating in 2016.

The main dam, called Pimental, had a dramatic impact on the river, creating a 359-square-kilometer reservoir and diverting much of the Xingu’s flow northeast through a 17-kilometer canal to a secondary reservoir and hydroelectric station. Downstream, along the 130-kilometer river stretch called the Big Bend of the Xingu, the diversion reduced the river’s flow by up to 80%. It also interrupted the river’s annual cycle of flooding, crucial to its rich biodiversity.

The Juruna call 2016, the year the main dam was completed, “the end of the world.” The impacts were evident right away, when an abrupt release of water from the dam killed 16.2 tons of fish. The Brazilian Institute of Environment and Renewable Natural Resources (IBAMA) imposed a fine of 35.3 million reais ($6.6 million) on Norte Energia, the company that runs the hydroelectric project. Josiel and other people from the Paquiçamba reserve were not surprised at the havoc. “The elderly in our villages knew we would have this kind of problem with the dam,” Josiel says. “We knew the fish would suffer with a river flow that is no longer natural.”

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This story was produced with support from the Rainforest Journalism Fund in partnership with the Pulitzer Center. It is also available in Portuguese.