Giant River Otter

The giant river otter (Pteronura brasiliensis) is the largest member of the mustelid family, which includes otters, weasels, and ferrets, and are by far the loudest member of the group. Giant river otters are very sociable and live in families of between 3-10 individuals that hunt together. The giant river otter competes with the black caiman for the title of maximum predator of the Amazonian lakes (cochas), a competition that can get so tense that it has been observed through physical confrontations. Its principal source of food are the fish from these cochas, forming an important part of the trophic balance of the aquatic ecosystem. The Giant River Otter is classified as “Endangered” in the IUCN Red List (2008) and has been included in Appendix I of the Convention on International Trade of Endangered Species since 1973. CITES is a document ratified by all South American countries. Regardless, given the large territory that this animal requires, the protection of this species is a complicated task that requires the joint coordination of multiple institutions.

Currently, the main threats to giant river otter populations are habitat degradation, river contamination due to mining and agriculture, overharvesting of fish, and hunting for its skin. WCS has monitored giant river otter populations in the Conservation Concession of Lago Preto Paredón. This research has focused on determining the necessary characteristics to recuperate these populations, like diet, behavior, and habitat, as well as understanding the resources it needs to support its re-establishment and incentivize conservation and management efforts of this species.

10 facts about the giant river otter:

  1. The giant river otter is giant, measuring in at 1.5-1.8 m and weighing in at 22-32 kg!
  2. In Peru, the giant river otter is classified as Endangered by the decree, DS 004-2014-MINAGRI.
  3. They’re semi-aquatic mammals, which means that they need both land and water habitat to survive.
  4. They are very social, forming groups of up to 10 individuals, made up of reproducing pairs and their offspring. They can have up to 6 pups per gestation period.
  5. Within the family group, the sub-adults act as “older siblings” and are in charge of taking care of the new batch of pups.
  6. They can live up to 10 years in their natural habitat.
  7. It has been studied that they can have up to 9 different type of vocalizations.
  8. Their fur is a dark brown with a white/beige patch that extends from its jaw line to its chest. This patch is unique on each animal and serves as a digital mark to identify individuals between them.
  9. It’s a carnivorous species with a diet almost entirely composed of fish.
  10. It doesn’t have any natural predators, but it can compete for food with other species such as the black caiman (Melanosuchus niger), the neotropical river otter (Lontra longicaudis), and, of course, the human (Homo sapiens).



Top photo: Walter H. Wust