Pink river dolphins are endangered because of a combination of threats that are killing them faster than they can reproduce. Deliberate hunting for fishing bait, mercury poisoning from gold mining, dam construction that fragments their habitat, and climate-driven heat events have all driven sharp population declines across the Amazon basin. In 2018, the International Union for Conservation of Nature reclassified the species from “Data Deficient” to “Endangered,” the second most alarming category on its Red List.
Killed for Catfish Bait
The single biggest direct killer of pink river dolphins is a commercial fishery for a scavenger catfish called piracatinga. Fishers slaughter dolphins and use their flesh as bait to attract the catfish, which feeds on carrion. In just one area of the central Amazon, an estimated 1,600 river dolphins were killed in a single year for this purpose. In Venezuelan rivers, roughly 840 were killed after the piracatinga fishery started there in 1990. Brazil imposed a moratorium on piracatinga fishing, but genetic testing of fish sold in markets has shown the ban is routinely violated, with piracatinga mislabeled as other species.
Mercury Poisoning From Gold Mining
Illegal and small-scale gold mining operations across the Amazon release mercury into rivers, where it accumulates in the food chain. Small organisms absorb it first, then fish eat those organisms, and dolphins eat the fish, concentrating mercury in their tissues at dangerous levels. One study found that 26 percent of river dolphins had mercury levels exceeding the threshold the World Health Organization considers safe for humans. Since dolphins are top predators in the river system, they accumulate some of the highest doses of any species. Mercury damages the nervous system, weakens immune function, and can impair reproduction, all of which compound the population’s decline.
The contamination spreads far beyond mine sites. Mercury travels through river systems and enters floodplain lakes where dolphins feed and raise calves, meaning even populations living hundreds of kilometers from active mines are exposed.
Dams Fragment Their River Habitat
Pink river dolphins depend on the seasonal rise and fall of Amazon rivers. During high water, they swim into flooded forests to hunt fish among the trees. During low water, they concentrate in deeper channels. Hydroelectric dams disrupt both of these patterns. They block migration routes, trap dolphins in isolated stretches of river, and alter the natural flood cycle that dolphins rely on for feeding and breeding.
The scale of dam construction in the Amazon is enormous. Researchers have documented 142 hydroelectric dams already operating or under construction in the western Amazon basin, with another 160 under consideration. Each dam has the potential to split dolphin populations into smaller, isolated groups that can no longer interbreed. Small, cut-off populations are far more vulnerable to local extinction because a single bad year, whether from drought, disease, or food scarcity, can wipe out an entire group with no possibility of recolonization from neighboring dolphins.
Extreme Heat and Drought
Climate change is intensifying droughts in the Amazon, and river dolphins are paying the price in dramatic fashion. In 2023, a severe drought caused water temperatures in Lake Tefé and Lake Coari to reach 40°C (104°F). The heat killed 330 dolphins, both pink river dolphins and their smaller relatives called tucuxi. It was the largest mass mortality event ever recorded for the species. Researchers at Brazil’s Mamirauá Institute confirmed that the deaths were caused directly by the extreme water temperatures.
What makes this especially alarming is that monitoring in subsequent years found water temperatures in 12 Amazon lakes already exceeding the levels recorded before the 2023 die-off. As droughts become more frequent and severe, these mass death events are likely to recur, hitting populations that are already depleted.
Boat Traffic Disrupts Communication and Feeding
Pink river dolphins navigate murky water almost entirely by echolocation, producing clicking sounds and listening for the echoes to locate fish, obstacles, and each other. Increasing boat traffic on Amazon waterways generates underwater noise that interferes with this system. Research on river dolphins has shown that vessel noise more than doubles metabolic stress and strongly masks their echolocation clicks, effectively blinding them in their own habitat.
The worst offenders are ferryboats and barges with uncased engines and poorly designed propellers, which produce noise that overlaps directly with the frequencies dolphins use. When dolphins can’t echolocate effectively, they miss feeding opportunities and burn more energy trying to compensate. Noise can also disorient them, pushing them closer to fishing nets or boat propellers. Over time, these disruptions reduce the overall fitness and survival of dolphins in busy waterways.
Slow Reproduction Makes Recovery Difficult
Even if every threat disappeared tomorrow, pink river dolphins would take decades to bounce back. Like most river dolphins, they reproduce slowly. Females don’t reach sexual maturity until around 8 to 10 years of age. Gestation lasts approximately 12 to 13 months, and after a calf is born, the mother typically nurses and cares for it for one to two years before she can breed again. The average interval between calves is roughly 3 to 4 years.
This means a single female might produce only 5 to 7 calves in her entire lifetime, and not all of those will survive to adulthood. When hundreds or thousands of dolphins are killed by bait hunters, poisoned by mercury, or wiped out in a heat event, the population simply cannot replace those losses quickly. This slow reproductive rate is what turns each of the other threats from a setback into a potential path toward extinction.
Overlapping Threats Compound the Danger
No single factor is pushing pink river dolphins toward extinction in isolation. A dolphin living downstream from gold mines carries mercury that weakens its immune system, making it more vulnerable to disease during a heat wave. A dam traps a small population in a stretch of river with heavy boat traffic, reducing their ability to feed efficiently. A nursing mother killed for bait removes not just one dolphin but her future offspring from the population for years to come.
These threats reinforce each other across the Amazon basin. The species’ range spans six South American countries with different laws, enforcement capacity, and economic pressures, making coordinated protection extremely difficult. Conservation groups including WWF and the Omacha Foundation have pushed for stronger protections, and their population studies were instrumental in securing the “Endangered” classification. But the dolphins’ future depends on addressing illegal fishing, mercury contamination, dam planning, and climate change simultaneously, not just one threat at a time.