The Yangtze river dolphin has been declared ‘functionally extinct’, which means that although there may be some of them left, there aren’t enough to breed and procreate; not enough to repopulate the species. The reason behind this tragedy is a combination of heavy water pollution and hydro-electric dam projects. Hydro-electric dams are harmful because they isolate groups of dolphins, effectively creating two smaller populations. This means that numbers are lower, and breeding is less likely.
Now there are fears for the future of another rare breed of dolphin, the Amazonian pink river dolphin. The government in Brazil are planning a hydro-electric plant in the middle of their habitat, and hunting also threatens the animals. Their flesh is often used as bait, and only fins are used. Many dead and mutilated bodies are found, often with the hunters name carved in the animals back. They're still widespread compared to other species in the area, but a sharp decline in numbers is ominous – roughly 10% per year. "I see that this is becoming the destiny of the boto of Amazonia," said Vera da Silva, a biologist at the National Institute of Amazonian Research in Manaus. ::The Guardian