Neotropical Otter is found in aquatic environments such as rivers, streams, lakes, lagoons, estuaries, mangroves, marshes and coastal shorelines (Rheingantz and Trinca 2015, Rheingantz et al. 2017a). This adaptable otter occurs in a wide variety of habitats from rocky shorelines to deciduous and evergreen forests, warm and cold climate rainforests, and coastal savanna swamps, rivers and mountain lakes from sea level up to 4000 m (Larivière 1999, Castro and Zapata Ríos, 2001, Rheingantz et al. 2014). It has been reported using coastal habitats and islands in Brazil (Carvalho-Júnior et al. 2006), as well as intermittent rivers in seasonally dry tropical forests of the Brazilian northeast region (Rosas-Ribeiro et al. 2017).

The otter has a long, dark brown, heavily built body with fully webbed feet. The species is flexible in its activity behavior, being more diurnal in the Pantanal and more nocturnal in the Atlantic Forest, perhaps due to more intense human activity in the latter (Rheingantz et al.  2016) and mainly nocturnal in Mexico, avoiding being exposed to higher air and water temperature. This also might explain their preference for shadowed areas in their river habitat where lower water and air temperatures are found (Gallo-Reynoso et al. 2019).

The Neotropical Otter is considered a solitary species, although pairs are observed during reproductive periods, and small groups of females and their cubs also occur (Rodrigues et al. 2013). Despite its high dependence on water, the species spends a considerable amount of time on land, especially in activities such as scent marking, reproduction and parental care (Rodrigues et al. 2013). Breeding occurs mostly during the dry or low water season but may occur throughout the year in some places (Parera 1996). Litter size varies from one to five cubs (Larivière 1999), with two or three on average (Parera 1996).

Otters are opportunistic predators that mainly prey on fish and crustaceans (Gallo-Reynoso 1997, Pardini 1998, Utreras et al. 2002, Rheingantz et al. 2017b), but also opportunistically consume amphibians, mammals, birds, and other prey (Rheingantz et al. 2017b). As an otter with a wide distribution range, L. longicaudis has a varied diet (Rheingantz et al. 2017b). 

Detailed data on population size and densities for the species are scarce and limited to small areas but suggest that Neotropical Otter populations are decreasing (Trujillo and Arcila 2006, Rheingantz and Trinca 2015). Recently, efforts by researchers have generated a more complete database on the species status at the continental level that allowed the IUCN Red List status up listing from Data Deficient to Near Threatened (Rheingantz and Trinca 2015).

The Neotropical Otter presents the broadest distribution among New World otters (Foster-Turley et al. 1990, Rheingantz et al. 2018), even though there are several areas where its presence is still uncertain. It occurs from north-western Mexico to Uruguay and across the northern part of Argentina to the Buenos Aires province. The species is widely distributed in southern Mexico, extending its range to the state of Morelos where its range is bifurcated until it reaches southern Tamaulipas on the side of the Gulf of Mexico, and to northern parts of Sonora and Chihuahua states, down to the South Pacific in Chiapas (Gallo-Reynoso 1997, Sánchez and Gallo-Reynoso 2007).

In central America, Lontra longicaudis is known to occur from the Pacific to the Caribbean regions of Costa Rica (Wainwright 2007), Guatemala (Quintana-Morales 2013) and Belize (Meerman and Clabaugh 2012), occurring in almost all countries. However, very little information is available from this portion of the species’ range. In Ecuador, the Neotropical river otter presents a wide range, occupying various habitats from the coastal lowlands to the Amazonia (Utreras et al. 2011, Utreras et al. 2013). There are extreme records of presence at 3,885 m a.s.l. (Castro and Zapata Ríos 2001). Recently, Neotropical Otter was recorded in new localities, such as areas surrounding the Ecuadorian and Colombian Andes (Rodríguez-Mahecha et al. 2006). In Bolivia the species is found across the Bolivian lowlands below 2,000 m a.s.l. (except the Chaco dry forests). There are occasional records at higher elevations on the humid eastern slopes of the Andes, reaching up to 3,200 m a.s.l. (Tarifa et al. 2010, Wallace et al. 2013).

In Brazil, Lontra longicaudis occurs in almost the entire territory, being absent only from a portion of the arid northeastern Brazil where river basins are fully located within Caatinga biome. Despite being absent from this more arid zone, the presence of the species was recently recorded in Caatinga, in intermittent stretches of river basins situated between the Caatinga and Atlantic Forest biomes, proving that the species can occur in semiarid conditions (Rosas-Ribeiro et al. 2017). The presence of Lontra longicaudis was also recently recorded in the coastal zone of the Atlantic Forest of northeastern Brazil (Astúa et al. 2010, Dantas and Donato 2011, Mendonça and Mendonça 2012, Souto 2012, Rosas-Ribeiro 2017), as well as in the eastern part of Amazonia, in Maranhão state (Mesquita and Meneses 2015).

Although Neotropical Otters are predicted to occur in all those areas, there are gaps in the data for the Brazilian Amazon, Pantanal and Paraguay.

Lontra longicaudis is legally protected in Argentina, Bolivia, Brazil, Colombia, Costa Rica, Guatemala, Ecuador, El Salvador, Honduras, Mexico, Nicaragua, Panama, Paraguay, Peru, Suriname, French Guiana, Trinidad, Tobago, Uruguay, and Venezuela. It is classified as Vulnerable (VU) in the Brazilian Atlantic Forest biome (Rodrigues et al. 2013) and on the Minas Gerais state Red List (Anonymous 2010a), as well as in Ecuador (Utreras et al. 2013) and Colombia (Rodríguez-Mahecha et al. 2006). It is considered Near Threatened (NT) in Bolivia (Zambrana et al. 2009), São Paulo (Bressan et al. 2009) and Paraná (Anonymous 2010b) states in Brazil, and Susceptible in Uruguay (González and Martinez-Lanfranco 2010). The species is Endangered (EN) in Argentina (Ojeda et al.  2012), Mexico (Sánchez and Gallo-Reynoso 2007), and in Central American countries such as El Salvador (Anonymous 2009a), Guatemala (Anonymous 2009b) and Nicaragua (Rivera and Manzanarez 2013). In Honduras, Neotropical Otter is listed as a Species of Special Concern (Cerrato et al. 2002) and it is protected under Act No. 4 of 1981 in Belize (Anonymous 2000). It is considered Critically Endangered in Trinidad and Tobago (Anonymous 2013) and it is protected and regulated by the Law of Conservation of Wildlife No. 7317 in Costa Rica (Anonymous 2005).

The Global Otter Conservation Strategy for the species (Rheingantz et al. 2018) recommends priority actions that include:

1. Mitigation of impacts of human activities such as dams, cooper and gold mining, agriculture, cattle ranching along rivers, deforestation and overfishing, as well as regulating the release of domestic and toxic waste in riverine systems near critical populations of otters.
2. Implementing monitoring programs with standardized methods in protected areas and combining data from all range countries to compare regional status.
3. Developing of National otter conservation plans for those range countries that do not yet have them, and implementation of such plans in range countries that already have them. National conservation plans determine regional threats and design specific conservation actions at a country and regional level.
4. Enforcement of existing legal protection, the expansion of protected areas that consider otters requirements, and the adoption of policies that mitigate the impact of humans on riverine and coastal habitats.
5. Surveys in areas with little information, such in Suriname, Guyana, Paraguay and most countries of Central America. We recommend long-term research inside and outside protected areas throughout the species range, to understand how human activities affect Neotropical Otter. Knowledge on the geographic distribution of the species needs to be improved, especially in the border areas of its distribution such as Mexico, Argentina and northeastern Brazil. This will advance an understanding of which climatic and ecological factors influence the limitations on the species range as well as the role of corridors and geographical barriers.
6. Public awareness of the ecological role of otters in aquatic systems and the impact of otters on fisheries need attention, particularly in areas of conflict. Effective education programs help change the negative perception of otters by fishermen in coastal and riverine habitats. Such programs already exist in Mexico, Colombia, French Guiana and Brazil, and need to be expanded throughout the species range. Training local people to work in the field and community involvement generates empathy for Neotropical Otter.
7. Development of strategies to prevent otter predation on fish farms and damage to fishnets. We recommend the adoption of fences in fish farms as used in Europe for Lutra lutra. A baseline evaluation of the economic impact of otters in fisheries and fish farms is also needed, and, at indigenous and community levels, the design and implementation of community agreements for responsible fishing.
8. Requirement of environmental impact studies for all hydroelectric projects and legal instruments to ensure compensatory measures for negative impacts on otters. Monitoring the impact of dams on Neotropical Otters before and after dam implementation is needed to assess changes in population dynamics and genetic structure.
9. Establishment of long-term Neotropical Otter conservation programs in Atlantic Forest coastal areas, Mexico, Brazilian Cerrado, Central America, Argentina and Amazon Basin.