In a significant conservation milestone, a family of giant river otters has been reintroduced to Argentina's Iberá Wetlands, marking the species' return to the region after over four decades. This initiative aims to restore the ecological balance of the wetlands by reintroducing a top aquatic predator.
The reintroduction program, led by Rewilding Argentina in collaboration with the provincial government of Corrientes and Argentina's National Parks Administration, began in 2017. The program involved sourcing suitable mates from international zoos, establishing breeding pairs, and preparing the otters for their eventual release into the wild. The first successful breeding occurred in May 2021, resulting in three cubs born in captivity. These cubs, along with their parents, were released into the Iberá Wetlands in July 2025, marking the first time a mammal declared extinct in Argentina has been brought back to the wild.
The giant river otter, Pteronura brasiliensis, is the largest of the world's 14 otter species, reaching up to 1.8 meters in length and weighing as much as 34 kilograms. Historically, the species inhabited a range stretching from northern Venezuela to Uruguay. However, hunting, primarily for its fur, led to population declines across much of its original range. The last family groups of giant otters in Argentina were observed in 1986, and the species was considered extinct in the country until recent reintroduction efforts.
Rewilding Argentina's conservation director, Sebastián Di Martino, emphasized the ecological importance of the giant river otter, stating, "The giant otter is the top aquatic predator in these wetlands, and its diet consists almost entirely of fish, so its presence contributes significantly to maintaining healthy ecosystems." The reintroduction of these otters is part of a broader effort to restore top predators in the Iberá wetlands. Since 2021, seven jaguars have also been released into the park, with the current population in Iberá now estimated at 16.
The Iberá Wetlands, one of South America's largest freshwater reserves, are home to a diverse array of flora and fauna. The reintroduction of the giant river otter is a crucial step in maintaining the delicate balance of this ecosystem. Conservation efforts in the region not only aim to restore biodiversity but also promote sustainable ecotourism, offering opportunities for wildlife observation and environmental education.