Giant otter

The giant otter (Pteronura brasiliensis) is a carnivore of the mustelid family, native to South America. It is the largest aquatic carnivore of this region and the largest otter in the world, measuring 1.8 m in length and weighing 33 kg.

Giant otters are mainly diurnal, social and territorial animals. They use water courses to feed and move, although they spend much of their time on the mainland where they move easily. In general, otters live in family groups, in which only the dominant female gives birth from one to three cubs per year, which are taken care of by the whole family.

The top predator of aquatic ecosystems

Most of the giant otter's diet is composed of fish although it may include crustaceans, mollusks and terrestrial vertebrates such as sub-adult caimans, birds or rodents. Due to its alimentary characteristics, this carnivore is usually a top predator in the trophic chains of the water courses where it lives, being a key species in these ecosystems.

The decline of their populations in South America

The species is listed as Threatened at an international level, Critically Threatened in most countries where it is distributed, and even considered Probably Extinct throughout Argentina according to the IUCN. The Argentine Society for the Study of Mammals considers it Critically Endangered and mentions that there are no records of a stable population or adult individuals with stable territories in Argentina in at least the last 30 years. It is likely that a combination of factors including habitat modification, pollution, poaching and conflicts with humans have caused the retraction of their populations in Argentina.

In the past, the distribution of the species was very broad, ranging from Guyana, Venezuela and Colombia, to northern Argentina and Uruguay and eastern areas of the Andes. At present, most of the giant otter populations are distributed discontinuously in the Pantanal, the Brazilian Amazon and the regions immediately adjacent to this area, French Guyana, Suriname and Guyana.

In Argentina the giant otter inhabited the basins of the Paraná and Uruguay rivers, including the Iberá wetlands. It also penetrated the Chaco region through rivers such as the Bermejo, reaching westward as far as Jujuy. The last records of the species in the country date back more than two decades, in the basins of the Iguazú, Paraná and Urugua-í streams in the province of Misiones, with a single recent occasional sighting in 2010 on the upper Iguazú river, in the area of ‘​​Garganta del Diablo’.

Historical presence of the giant otter in Iberá

In the province of Corrientes there are citations mainly along the Paraná rivers (even until 1993) and Uruguay. There are also unconfirmed records in the departments of Ituzaingó and Paso de los Libres. In Iberá, which is connected to the Paraná River through the Corrientes River and the Uruguay River through the Miriñay River, the best-known citation of the species is a skull found in Fernández Lagoon. There are also reports of the presence of the species in the area of ​​Rincon del Diablo, Capitá Miní, Yahaveré, Itatí Rincón lagoon, Misteriosa lagoon, Sanchez stream (a few kilometers north of the town of Colonia Carlos Pellegrini) and in the wetlands of Miriñay , west of the town of Tapebicuá.

The opportunity to recover the largest aquatic predator in the wetlands

The absence of top predators in Iberá, such as the jaguar and the giant otter, implies an imbalance in the ecosystem, as they lose their roles as regulators of prey populations. In addition to the ecological effect of restoring a top predator in the ecosystem, the reintroduction of the giant otter represents another important resource for ecotourism in the regions. In this context, and based on a list of recommended species to be reintroduced in Iberá, the giant otter reintroduction project has been proposed, which added to the jaguar represent the two top predators in the aquatic and terrestrial ecosystems of the area, respectively.