TEFÉ, Amazonas — “I’ve lived on this floating home for 40 years, and this is the worst drought I’ve ever seen. You can see that the water dropped well below the 2023 levels,” says Carlos Magno, as he shows the point reached by the water last year. “That’s a scary scenario to watch. And it gets even scarier because of the news that this is going to get worse every year.”

Magno is a boat mechanic and lives on a floating house on the water, usually built of wood or metal, on the shores of Lake Tefé, in the municipality of the same name located in the heart of Amazonas state. While he and his family love living by the lake, where they are surrounded by water, forest and animals, they are now considering moving to dry land because of increasingly severe droughts.

“The floating house is already completely on land. Take a look here to see how much the water level has dropped. This drought is almost 30 days longer; it usually doesn’t get to this point,” he says, worried. The water needs to rise so Magno can get back to work. Because of low river and lake levels, boats stop traveling and he loses clients. He has had no work for two months now.

Lake Tefé, a lagoon formation of the Tefé River near the point where it meets the Solimões, has been experiencing a historic drought this year, reaching just 4.5 meters (14.9 feet) — 13.5 m (44 ft) below its June level, at the beginning of the dry season, when it was 18 m (59 ft) deep (see graph below). In addition to the drastic reduction, the remaining water recorded extremely high temperatures, reaching 40.3º Celsius (104.5° Fahrenheit), the same as in 2023, according to data from the Mamirauá Institute for Sustainable Development (IDSM).

Throughout the Amazon, 69% of municipalities have been recording drought rates that are even more intense than those of 2023 — a 56% increase over the same period last year, according to the Integrated Drought Index (IIS). In Amazonas, the state government’s 2024 Drought Bulletin indicates that another 850,000 people were impacted by lower water levels, and all 62 municipalities are in a state of emergency. According to the Geological Survey of Brazil, the situation could become worse by December.

“In recent decades, we have observed extreme hydrological events intensifying, with record floods and droughts year after year,” says Ayan Fleischmann, a senior researcher at the Mamirauá Institute’s Research Group on Geosciences and Environmental Dynamics in the Amazon.

Monitoring is also carried out by a platform developed by the World Wildlife Fund Brazil (WWF-Brazil) and MapBiomas, which monitors 23 of the more than 60 lakes in the Amazon Basin. It revealed that the waters of lakes connected to rivers have also reached higher temperatures since August.

In 2024, 12 of these lakes already have seen temperatures above those recorded in 2023. The data also show that these lakes have had average temperatures above those of the previous year for 5-9 months, which points to physiological stress experienced by living beings repeatedly exposed to high temperatures and low water levels.

That is the case of dolphins.

In the waters, a tragedy foretold

In Lake Tefé, in September and October 2023, 209 carcasses of pink river dolphins (Inia geoffrensis) and grey river dolphins locally known as tucuxi (Sotalia fluviatilis) were collected, according to researchers from the Mamirauá Institute. On Sept. 28 alone, 70 carcasses were found in the area, an unprecedented mortality event for these species. That year, most of the deaths were related to the overheating of the waters, which reached temperatures above 40ºC.

According to estimates made by the Mamirauá Institute, Lake Tefé is home to approximately 900 pink dolphins and 500 tucuxis. With an annual replacement rate of only 5%, the loss of more than 200 animals in 2023 represented a significant impact on these populations. About 80% of the animals killed that year were pink dolphins.

Both species of Amazonian freshwater dolphins are on the International Union for Conservation of Nature (IUCN) Red List of Threatened Species. The pink dolphin and the tucuxi are considered “endangered,” meaning the species will likely become extinct in the near future. This is the second most serious level of threat on the IUCN list.

In 2024, the Chico Mendes Institute for Biodiversity Conservation (ICMBio) and the Mamirauá Institute decided to anticipate the tragedy. “The drought was so intense last year that the river never recovered its level. We already started with water shortage. The expectation was that the tragedy would repeat itself,” says Miriam Marmontel, leader of the Mamirauá Institute’s Amazonian Aquatic Mammals Research Group. “We were prepared for a new emergency, with more intense monitoring, team training and acquisition of specific equipment.”

Given the high number of dead animals, ICMBio established the Tefé Dolphin Emergency in 2023, an operation to investigate the situation, with technical support from the Mamirauá Institute and in partnership with several institutions. The agency also launched the 2024 Aquatic Fauna Emergency in September, in order to strengthen monitoring of animals in the area and prevent new deaths. More than 50 professionals were in charge of monitoring water conditions and animal behavior twice a day.

However, the dolphin mortality rate was not as expected. “This year was drier; it was very hot, and we didn’t see any dolphins dying. We didn’t understand,” says Magno, who, in 2023, helped collect and transport carcasses that often ended up in his backyard.

Valdinei Lemos Lopes, who has worked with dolphins for more than 20 years and has collaborated with the National Institute for Amazonian Research and the Mamirauá Institute, says he believes the animals anticipated an even more severe drought and moved to safer places. “The animals know more than we do; after all, they live there. Last year, the drought came suddenly, and they didn’t have time to leave the lake. This year, they made sure to leave it earlier,” he explains.

According to Fleischmann, what prevented the 2023 tragedy from being repeated was the lower incidence of solar radiation. This year, there were fewer consecutive days of intense sunlight as well as more rainfall and clouds, which prevented the lake from remaining at 40ºC for long periods.

“The water temperature in Lake Tefé varies a lot. It can go from 27ºC [81°F] in the morning to 40ºC in the afternoon in a single day. This affects all beings in the aquatic environment but does not result in extreme overheating of its waters,” Fleischmann says.

In short: In 2024, no deaths of dolphins related to thermal stress were recorded. However, ICMBio recorded 14 animal deaths, including eight pink dolphins, four tucuxis and two manatees, all with signs of contact with human activities such as fishing, hunting or collisions. The carcasses of these animals are being examined to determine the exact causes of death.

But drought is still the element behind the deaths of these animals. With low waters, aquatic mammals become more vulnerable and are exposed to adverse human activities such as fishing, hunting and collisions with boats.

Sea Shepherd monitors the local fauna in the area of Coari, a city near Tefé. They counted 37 carcasses, including 22 tucuxis, five pink dolphins, two unidentified dolphins, four manatees and four manatee parts. Although some animals were already in an advanced stage of decomposition, all had signs of human action. “We found the animals with marks of fishing nets and stab wounds,” Sea Shepherd executive director Nathalie Gil says.

She reports that, in the first week of monitoring, the team observed signs of illegal hunting from a distance. In an operation with the State Police, they found a buoy with two dead manatees.

“Manatees are the target of excessive hunting, and they are consumed in Coari. We are talking about major consumption, with 15-20 animals caught every day,” Gil says. The Amazonian manatee is one of the 1,182 Brazilian species threatened with extinction. They are listed as “vulnerable” on the Official List of Endangered Species of Brazilian Fauna.

The battle between dolphins and fishers

Although dolphins are not directly targeted by hunting, they are engaged in a battle with the local fishers. According to fisherman Edinei de Lima Ferreira, pink dolphins are “lazy.” They wait for the gillnet, a fishing net made of mesh, to fill with fish so they can rip it open and eat. “The dolphin rips the net, and we lose all the fish,” Ferreira says.

“We work so hard to mend the net and put it in the river, and then that animal comes and rips everything. If only they’d take the fish politely, I wouldn’t get angry,” he says. “But if we could, we’d kill them all,” he jokes.

However, walking around the city of Tefé or sailing along the rivers, it is possible to see that the tension between dolphins and fishers is serious. Lemos Lopes, who has years of experience with the species, says it is rare to find someone in the area who likes dolphins. “Some people think they are beautiful, but as long as they are far away, not around. There is also fear of the legends that say the dolphins may cause harm.”

In Brazilian folklore, pinks dolphins are known for their mystical ability to seduce. Legend has it that, on full moon nights, the animal emerges from the rivers as an attractive man capable of conquering a young woman and impregnating her before returning to the waters.

It is now known that the legend of the pink dolphin is strongly linked to cases of sexual violence in the area. However, for many years, it fueled persecution of these animals, which were killed for fear of their supposed powers of seduction. There are also reports that dolphin parts were worn as amulets and that the animal’s fat was used for medicinal purposes. While the legend is no longer the main reason for hunting, retaliatory capture still occurs in some places.

In the struggle between fishers and dolphins over fishing resources, the resentment of the former has been drawing researchers’ attention. To avoid conflicts, sound devices are being developed that keep dolphins away from fishing nets, preventing both the destruction of gillnets and retaliation against the animals.

WWF-Brazil, together with the Society for Environmental Research and Protection, began testing this technology in June 2023 at the Prainha I community, in Pará’s Tapajós National Forest, where conflicts are common. In the first tests, there was a 40% reduction in damage to gillnets and a threefold increase in the amount of fish caught. However, effectiveness decreased in the second phase of testing, when the dolphins began to adapt to the noise and find new ways of approaching.

Karen Lucchini, a researcher at the Aquatic Mammals Center, points out that these devices, called pingers, were originally designed for the marine environment and that their adaptation for use in rivers requires significant adjustments. Getting people to adopt the technology is another challenge. “We face resistance from fishers, who fear that their catches will decrease with the use of these devices. Furthermore, their cost is high, and adapting these technologies in an accessible way is still difficult.”

Banner image: A pink river dolphin is found dead in an Amazon river. Image provided by Sea Shepherd Brazil.

This story was first published in Portuguese here on Nov. 27, 2024.