The boto (Inia geoffrensis) — the world's largest river dolphin — inhabits the Amazon and Orinoco basins. Listed as Endangered, botosdeclined significantly from deliberate killing for use as catfish bait (piracatinga fishery). Brazil banned boto killing in 2015, but poaching continues in remote areas. Botoswelfare is further compromised by mercury contamination from illegal gold mining. These highly intelligent, individually-recognizable dolphins form complex social relationships — individual welfare losses are significant.
The giant otter (Pteronura brasiliensis) was nearly hunted to extinction for pelt trade; recovery has been partial to approximately 5,000 individuals. Family groups occupy river territories and are highly susceptible to mercury contamination through fish consumption. Welfare monitoring studies tracking individual families in the Pantanal, Amazon, and Orinoco reveal that mercury exposure from mining upstream reaches dangerously high levels in individuals. Tourism-based giant otter watching in Manu (Peru) and Pantanal provides non-consumptive welfare-compatible use.
Approximately 30 freshwater stingray species (Potamotrygonidae) are endemic to South American rivers. Several are harvested for the ornamental fish trade. Their venomous spines make handling dangerous; capture and transport stress is significant. Welfare considerations for ornamental trade stingrays include transport conditions, appropriate captive tank conditions, and sourcing verification (wild vs. captive bred).
The arapaima (Arapaima gigas) — potentially the world's largest scaled freshwater fish, reaching 3m — was nearly extinct from overfishing. Community-based management programs in Brazilian Amazon have enabled population recovery while providing sustainable harvest. Welfare of arapaima in community management systems includes monitoring of fishing methods and population health indicators. Captive arapaima farming is developing as an alternative to wild harvest.
Major dam construction across South American rivers — Belo Monte (Amazon), Tucuruí, and hundreds of planned projects — disrupts fish migration, kills downstream fish from turbine mortality, and causes upstream reservoir flooding of forest habitat. Aggregate freshwater welfare impacts of dam development across the continent are enormous, affecting billions of individual fish across thousands of species.