Loutre d'AmériquedDu Sud

The modification and fragmentation of natural habitats by human activities represents the main threat to the species, leading to population isolation and reduction. The species may occur in areas with some degree of human activity and habitat degradation (Rheingantz et al. 2014, Rheingantz and Trinca 2015, Rheingantz et al. 2017a), but its presence has been negatively correlated with human population density (Gomez et al. 2014, Rheingantz et al. 2014). There are stable populations in more pristine areas throughout the species’ range, but populations are decreasing in more heavily human-modified areas (Rheingantz and Trinca 2015).

The species was severely hunted until the 1970s for the international fur market, with hundreds of thousands of pelts exported from South American ports between 1945 and 1975 (Brack Egg 1978, Donadio 1978, Larivière 1999, Utreras and Jorgenson 2003). Despite the ban on the international pelt trade, Neotropical Otters are still hunted illegally and killed in conflicts with fishermen and fish farmers due to supposed fish depredation (Chehébar 1990, Barbieri et al. 2012). Although fishermen often have a negative perception of the otter, many of them report that actual damage from Neotropical Otter is small (Fonseca and Marmontel 2011, Barbieri et al. 2012, Castro et al. 2014, Hernández-Romero et al. 2018). Indeed, fishermen from northeastern Mexico showed a positive attitude toward the development of conservation actions for the otter (Mayagoitia-González et al. 2013). Otters can also become entangled in fishing nets, as reported in southern Brazil (Quintela et al. 2011).

Bioaccumulation of toxins is known to harm the species (Josef et al. 2008, Ramos-Rosas et al. 2013). Mercury has been observed in fur and tissues samples of the species from the Pantanal (Fonseca et al. 2004), as well as high levels in otter spraints from southeastern Brazil (Josef et al. 2008). Studies show that Neotropical Otter may have high levels of other heavy metals such as lead and cadmium even in protected areas of Mexico (Ramos-Rosas et al. 2013), and other Persistent Organic Pollutants (Latorre-Cárdenas 2013). Industrial waste spills increase heavy metal levels in watercourses and have been associated with otter mortality in Mexico (Gallo-Reynoso 1997). In Ecuador, recent oil spills, increasing mining activities, intense use of agrochemicals and incorrect treatment of residual waters from the cities continue increasing the pollution of many hydrological systems where otters are present. Among other threats, we also find destructive fishing practices including the use of dynamite, electrocution and chemicals.

Roadkills of Neotropical Otters have been documented in the Guianas (Duplaix 2004), in southern and southeastern Brazil (Quintela et al.  2011), in Costa Rica and Mexico (V.M. Santiago-Plata pers. comm.).

Episodes of intense rainfall are becoming more frequent and when combined with deforestation along riverbanks, can cause landslides and flooding. According to Navarro and Quadros (2017) this can force otters to abandon an area, to which they return slowly.  

Severe and long drought periods cause additional ecological stress to Neotropical Otters, which can be worrying if compounded with other normally tolerated environmental impacts, as pollution, cattle ranching and deforestation. This may have been the cause of the recent absence of Neotropical Otters in some river basins of Piauí state (Northeastern Brazil), where otters have not been seen in the last 50 years (Rosas-Ribeiro et al. 2017).

The effect of cattle ranching in the riparian habitat of some rivers in Mexico, as well in other countries, has devastated the biodiversity, causing significant riverbank erosion and turning the river ecosystem into an anoxic environment with reduced fish availability. There is also a concern that zoonotic diseases may be transmitted by cattle (J.P. Gallo-Reynoso pers. comm.).

The long-term impacts of dam construction on the species are poorly understood. Dams degrade the environment by changing flowing to standing water and by decreasing functional connectivity for both individuals and populations. Dams also change the local prey community, affecting otter diet in unknown ways (Quadros 2012).

The protozoans Giardia spp. and Cryptosporidium spp. were recently first reported for L. longicaudis from northern and northeastern Brazil (Borges et al. 2017a, b). Although clinical significance of these results is still unclear, they raise concerns about transmission to other aquatic mammals and even humans, since oocysts and cysts may remain infectious for long periods (LeChevallier et al. 1991). Mortality of otters due to diseases such as canine distemper (Hernández-Romero pers. obs.) is also a threat. Canine parvovirus infection was documented in an adult otter in southern Brazil, that died after treatment (Echenique et al. 2018). This problem is rapidly expanding to rural areas, where interactions with feral dogs and cats are more frequent. The intensity and impacts of diseases on local otter populations need to be further investigated.

The use of Neotropical Otter cubs as pets has been reported in several states of México (Gallo-Reynoso 1989), in the Brazilian Amazon (Marmontel et al. 2011, Fonseca da Silva pers. comm.), and in northern Costa Rica (Santiago-Plata pers. comm.), Colombia (Restrepo et al. 2018) and the Coast and Amazon region of Ecuador (Utreras et al. 2013). In some locations, medicinal use of otters has been documented, for example, in the Brazilian Amazon an infusion of Neotropical Otter skins is said to cure shortness of breath and asthma (Fonseca and Marmontel 2011).

The intensity and effect of these threats on otter populations is poorly known, but there is a perception that populations are declining across the range (Rheingantz and Trinca 2015). Considering the expansion of human activities in Latin America, this otter may be subjected to further population decline in the future. This is more acute in some regions, such as in northeastern Brazil, where otter populations are concentrated in well-drained lowland rivers, which are also prime locations for agriculture, ranching and other human activities (Rosas-Ribeiro 2017).

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.