Intrepid as Crocodile Dundee, Ricardo Freitas captures a caiman in the middle of the night using a pole fitted with a snare, before hoisting it onto his small wooden boat.
Without trembling in the face of the animal’s sharp teeth, this 44-year-old Brazilian biologist grabs it by the snout, which he surrounds with black insulating adhesive tape to examine it in complete safety.
The approximately 5-foot-tall saurian is at home in the Jacarepagua Lagoon, a vast collection of neighborhoods in western Rio de Janeiro whose name means “Valley of the Caimans” in the indigenous Tupi-Guarani language.
But it has been decades since this place has been anything but a bucolic valley with lush tropical vegetation.
Endless bars of posh residential buildings stand all around the lagoon, into which the wastewater of tens of thousands of residents flows.
Biologist Ricardo Freitas holds a caiman captured in the Jacarepaguá lagoon, in the Recreio dos Bandeirantes district, west of Rio de Janeiro, on November 22, 2023 in Brazil / Tercio TEIXEIRA / AFP
A pestilential odor escapes from the greenish water.
Just in front of Ricardo Freitas’ boat, you can see the thirty 17-story buildings of the former Olympic village for the 2016 Olympics.
The biologist is categorical: hit hard by this urban expansion and the pollution that goes with it, the Jacarepagua caiman is “threatened with extinction”.
According to his estimates, the region has around 5,000 caimans of the so-called “broad-snouted” species, by its scientific name Caiman latirostris. The largest can exceed three meters in length.
Air view of the Canal das Taxas, in the quarter of Recreio dos Bandeirantes, west of Rio de Janeiro, on 22 November 2023 in Brésil / Tercio TEIXEIRA / AFP
But Rio’s Crocodile Dundee has identified a serious problem: 85% of the specimens it has examined recently are males. An imbalance due, according to him, largely to the pollution of the lagoon.
“Caimans lay their eggs in very polluted areas, where the water temperature is higher, which favors the birth of males,” he explains.
“These are animals that depend on the incubation temperature for sex formation. In water at 29 or 30 degrees, we would have more females. But here the water is much warmer because of the decomposing materials” .
Biologist Ricardo Freitas measures a caiman captured in the Jacarepaguá lagoon, in the Recreio dos Bandeirantes district, west of Rio de Janeiro, on November 22, 2023 in Brazil / Tercio TEIXEIRA / AFP
Beyond the caiman, the entire local ecosystem is threatened. “As it is at the top of the food chain, it plays a vital role in maintaining the balance of species. Without the caiman, biodiversity is totally compromised.”
In more than 20 years of research on the Jacarepagua lagoon on behalf of his NGO, Instituto Jacaré, this doctor in ecology, member of the international collective of experts Crocodile Specialist Group IUCN/SSC, has captured more than 1,000 caimans, listed in a database of data.
Biologist Ricardo Freitas takes a dorsal scale from a caiman captured in the Jacarepaguá lagoon, in the Recreio dos Bandeirantes district, west of Rio de Janeiro, on November 22, 2023 in Brazil / Tercio TEIXEIRA / AFP
On his boat, before releasing them, he weighs them, measures them and takes dorsal scales. Analyzed in the laboratory, they make it possible to identify levels of contamination with heavy metals such as lead, chromium or mercury.
Pollution is also revealed during gastric washings administered to saurians. “I found all kinds of waste: plastic bags, pieces of cans, pieces of balloons used for parties and even condoms!”, he describes.
“Everything is abandoned”
Due to urban expansion, the natural habitat of caimans is increasingly reduced. They end up concentrating in inhabited areas littered with trash, where they find food more easily.
A caiman swims among the waste of the Canal das Taxas, in the Recreio dos Bandeirantes district, west of Rio de Janeiro, on November 22, 2023 in Brazil / Tercio TEIXEIRA / AFP
In a canal that crosses Terreirao, a working-class neighborhood located a few kilometers from the lagoon, the caimans literally swim among the rubbish.
Near a bridge, we can only see the snout of one, which emerges from a carpet of waste, between an old dismembered doll and a burst soccer ball.
“It’s sad to see them in the middle of all this pollution. It’s a little scary to see them so close, but they almost never come out of the water,” says Regina Carvalho, a 34-year-old childminder.
When torrential rains cause the canal to overflow, residents sometimes come face to face with a caiman when leaving their homes.
A caïman naged the Canal das Taxas, in the quartier of Recreio dos Bandeirantes, west of Rio de Janeiro, on 22 November 2023 in Brésil / Tercio TEIXEIRA / AFP
But Alex Ribeiro, who runs a cleaning products store, has “never heard of attacks” by saurians.
“Here, everything is abandoned, wild pipes connect the canal to all the houses in the surrounding area. We can imagine the level of pollution to which the caimans are exposed,” summarizes this 58-year-old trader.