Their natural prey includes many types of fish, crustaceans, mollusks, and occasionally birds or their eggs, particularly of ground-nesting species found near water.

The North American river otter, by comparison, largely inhabits inland freshwater riverine habitats, or lakes, preferring not to venture to the seashore to hunt, even in areas where its range is close to the ocean.

Dam and road construction, as well as stream canalization and drainage for agriculture destroy many acres of what could be habitat for this species.

Several surveys and studies have been performed to better understand the southern river otter and its declining population, in an effort to prevent the species from facing a rapid extinction.

[5] One survey was undertaken to determine if any southern river otters live within the protected bounds of three Argentine parks—Lanín, Puelo and Los Alerces National Parks.

Mink were introduced and/or escaped into the area over many years, and are thought to directly compete with the southern river otters for resources and habitat, as they lead similar amphibious lifestyles and hunt the same basic prey species.

[5] Future directions for conserving this species include obtaining better information on the southern river otter's population numbers and locations.

If conservationists know where the individuals and families live, enforcement of antipoaching laws, as well as focusing on maintaining and protecting their habitats, will be easier.