# Giant Otter — Facts, Threats & Conservation

*Pteronura brasiliensis*

> A giant otter (Pteronura brasiliensis) is the world's longest otter, a fish-eating, highly social mammal of South American rivers that grows up to 1.8 metres long and lives in family groups; it is classified as Endangered by the IUCN.

**IUCN status:** Endangered (IUCN, 2021) — locally extinct or Critically Endangered across much of its former range  ·  **WARN range:** Brazil, Colombia

## Quick facts
| Fact | Value |
| --- | --- |
| Lifespan | ~8 years wild; up to 17 in captivity |
| Weight | Males 26–32 kg; females 22–26 kg |
| Length | Up to 1.8 m (nose to tail tip) |
| Diet | Carnivore — mainly fish (cichlids, characins, catfish) |
| Gestation | ~65–70 days |
| Young per birth | 1–5 pups (average about 2) |
| Baby name | Pup |
| Group name | Family group (3–8 members; also called a romp or raft) |
| Habitat | Slow-moving rivers, lakes and wetlands of South America |
| CITES | Appendix I (commercial international trade banned) |

## Scientific classification
- **Kingdom:** Animalia
- **Phylum:** Chordata
- **Class:** Mammalia
- **Order:** Carnivora
- **Family:** Mustelidae
- **Genus:** Pteronura
- **Species:** Pteronura brasiliensis (Gmelin, 1788) — monotypic genus

## Conservation status
- **Status:** Endangered
- **Population:** Fewer than 5,000 mature individuals (no precise global count; populations fragmented)
- **Trend:** Decreasing
- **Assessed:** 2021
- **CITES:** Appendix I
- The single 'Endangered' badge masks worse local realities: the giant otter is extinct in Argentina and Uruguay, reduced to a tiny remnant in Paraguay, and considered Critically Endangered in some range states. Gold-mining and mercury pollution are growing threats.

## Key facts: Giant Otter
- The giant otter is the longest member of the weasel family (Mustelidae), reaching up to 1.8 m including the tail.
- It is a cooperative, diurnal hunter that catches fish — mainly cichlids, characins and catfish — eating several kilograms a day.
- Family groups of 3–8 share a territory, raise pups together, and communicate with at least nine distinct vocalisations, earning the name 'river wolf'.
- Each animal has a unique cream-coloured throat patch, like a fingerprint, used by researchers to identify individuals.
- Hunting for the international fur trade collapsed populations in the 20th century; CITES banned commercial trade and listed it on Appendix I.
- Today it is Endangered, threatened by habitat loss, gold-mining and mercury pollution of its rivers.

## Why the giant otter is endangered
From the 1940s to the 1970s the giant otter was hunted relentlessly for its thick, water-repellent pelt, and tens of thousands of skins were traded internationally until CITES protection arrived in the 1970s. Populations have never fully recovered. The IUCN, in its 2021 assessment, lists the species as Endangered, with a population suspected to have fallen by more than half over the past three generations. The species is now extinct in Argentina and Uruguay, reduced to a tiny remnant in Paraguay, and fragmented across the Amazon and Orinoco basins. Because giant otters are conspicuous, curious and live in open river systems, they are unusually easy to disturb or extirpate.

## Behaviour and ecology
Giant otters are among the most social of all carnivores. A family is built around a single breeding pair and their offspring from several years, who hunt, patrol and rest together. They are active by day, relying on keen eyesight to chase fish in shallow water, and they haul out onto communal bank dens and latrine sites that scent-mark the group's territory. Their loud, varied calls — snorts, screams, hums and warning barks — coordinate the group and warn of danger, which is why locals call them lobo del río, the river wolf. As apex predators they help keep fish populations and river food webs in balance.

## Threats today
The fur trade is gone, but newer pressures have taken its place. Deforestation and cattle ranching strip the forested riverbanks otters depend on; dams fragment river systems; and overfishing reduces their prey. The gravest emerging threat is artisanal gold mining, which both destroys habitat and floods rivers with mercury — a toxin that accumulates in the fish otters eat and in the otters themselves. Disturbance from unregulated tourism and conflict with fishers add further pressure to small, isolated groups that cannot easily recover.

## What rescue and protection involve
Protecting giant otters is mostly about protecting living rivers. Effective work combines guarding key wetland strongholds, curbing illegal mining and mercury pollution, restoring riverbank forest, and reducing conflict with fishing communities. Because the animals are wide-ranging and sensitive to disturbance, hands-on rescue is rare and is usually limited to orphaned or injured individuals; the durable gains come from habitat protection and from local teams monitoring family groups and their territories season after season.

## Giant otter vs. neotropical (Southern) river otter — telling the two apart
| Feature | Giant Otter (Pteronura brasiliensis) | Neotropical Otter (Lontra longicaudis) |
| --- | --- | --- |
| Length | Up to 1.8 m — the longest otter | About 0.9–1.3 m |
| Weight | 22–32 kg | 5–15 kg |
| Sociability | Highly social; family groups of 3–8 | Mostly solitary |
| Throat patch | Distinctive cream/white patch, unique per animal | Faint or absent, paler underside |
| Activity | Diurnal (active by day) | Mainly nocturnal/crepuscular |
| IUCN status | Endangered | Near Threatened |

## What WARN does
WARN CIC is a registered global not-for-profit animal welfare organisation that funds local partner shelters, sanctuaries and rescue teams in five countries — Pakistan, Indonesia, Malaysia, Brazil and Colombia. The giant otter's range falls squarely within two of those countries: Brazil's Amazon and Pantanal and Colombia's Amazon and Orinoco rivers are global strongholds for the species. WARN's funded focus there is to back local partners working on river-habitat protection, anti-mining and anti-pollution efforts, and the care of orphaned or injured wildlife, while supporting wider public education about why these rivers matter. WARN does not run its own field stations; its honest role is to channel donations to the people already doing this work on the ground.

Brazil and Colombia hold some of the last great strongholds of the giant otter — and your gift helps WARN fund the local partners protecting those Amazon and Pantanal rivers, fish by fish, family by family.

## Frequently asked questions: Giant Otter
### How long do giant otters live?
In the wild giant otters typically live around 8 years; in captivity they can reach 17 years or more, with one unconfirmed record near 19.

### What do giant otters eat?
They are carnivores that eat mainly fish — especially cichlids, characins and catfish — and will also take crabs, snakes and occasionally small caimans. An adult eats roughly 3–4 kg of fish a day.

### How big is a giant otter?
It is the longest otter in the world, reaching up to about 1.8 m from nose to tail tip. Males weigh roughly 26–32 kg and females 22–26 kg.

### Are giant otters dangerous to humans?
They generally avoid people, but they are powerful apex predators that defend their group fiercely. Cornered or provoked otters can deliver serious bites, so they should be observed from a distance and never approached.

### How many giant otters are left?
There is no precise global count, but the IUCN estimates fewer than 5,000 wild individuals in fragmented, declining populations, which is why the species is classed as Endangered.

### What is a baby giant otter called?
A baby giant otter is called a pup. Litters usually contain 1–5 pups (about 2 on average) after a gestation of roughly 65–70 days, and the whole family helps raise them.

## Sources
- [IUCN Red List — Pteronura brasiliensis (Giant Otter), 2021 assessment](https://www.iucnredlist.org/species/18711/164580466)
- [CITES — Appendices (Pteronura brasiliensis, Appendix I)](https://cites.org/eng/app/appendices.php)
- [WWF — Giant otter (Amazon species)](https://www.worldwildlife.org/species/giant-otter)
- [Smithsonian's National Zoo & Conservation Biology Institute — Giant otter](https://nationalzoo.si.edu/animals/giant-otter)
- [Animal Diversity Web — Pteronura brasiliensis](https://animaldiversity.org/accounts/Pteronura_brasiliensis/)
- [Mammalian Species (Oxford) — Pteronura brasiliensis](https://academic.oup.com/mspecies/article/49/953/97/4107303)

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Full guide: https://worldanimalrescuenetwork.org/wildlife-guides/giant-otter