Species guide: Although dolphins and porpoises are not typically associated with freshwater, there are five unique species of freshwater dolphin and one species of freshwater porpoise, most of them endangered…

Which Dolphin?

The taxonomy of cetaceans is currently undergoing major change in the view of new genetic techniques that are currently being applied to populations and species. This has affected changes in the classification of river dolphins and other freshwater dolphin and porpoise populations both in family, species and subspecies classifications. In order to maintain the most up to date developments, the information on this page reflects changes outlined in Rice (1998) and adopted by the IUCN (World Conservation Union).

It’s worth noting that there remains some confusion, particularly among the general public as to which species are included in the term ‘River Dolphin’, not surprisingly since one of the species of so-called ‘true’ river dolphins is actually a marine species, whilst other populations of marine species have sub-species which are found exclusively in freshwater. The new taxonomy adopted here, allows us to be specific about the species and subspecies that are found exclusively in freshwater, river environments and which areas of the world they are found. For this reason, we are going to include them all within the umbrella of ‘Freshwater dolphins and porpoises’.

Freshwater Dolphins and Porpoises

"True" river dolphins

Of the four true river dolphin species previously grouped within the family Platanistidae, only three inhabit exclusively freshwater environments; the Baiji in the Yangtze River in China, the Boto in the Amazon and Orinoco River basins in South America and the Susu in the Ganges and Indus Rivers in India and Pakistan. The Fransiscana (Pontoporia blainvillei) is a small marine species that occurs along limited stretches of the east coast of South America. Whilst it is not a truly freshwater dolphin there is serious concern over its future conservation status.

Other freshwater dolphins and porpoises

Populations of other cetacean species that are found to inhabit freshwater environments are also critically threatened by the same factors that affect the Baiji, Boto and Susu. They include:

Yangtze River finless porpoise, a population of finless porpoise found exclusively in the Yangtze, now identified as a separate subspecies from the population found in the Indian Ocean and South China Sea and the population found around China, Korea and the coast of Japan.

Freshwater tucuxi, a freshwater population of the tucuxi which is found in the Amazon and Orinoco Rivers in South America.

Irrawaddy dolphin, populations of which are found in freshwater stretches of the Mekong in Laos and Cambodia, the Mahakam River in Indonesia and the Ayeyarwady River (formerly Irrawaddy) in Myenmar (formerly Burma). In addition, several populations also occur in brackish water environments in Chilka Lake in India and Songkhla Lake in Thailand. Songkhla Lake is both brackish in some places and freshwater in others and this population has therefore been included within this text.

Conservation Status

All the freshwater dolphins and porpoises shown above are CITES Appendix 1 listed apart from the Boto which is listed Appendix 2. All of the Asian river dolphins have suffered dramatic declines in both their range and numbers over the last three decades to the point at which they rank as some of the most endangered of all mammals. In addition to the CITES listings, the IUCN World Conservation Union has classified the species in to categories according to threat. The most critically endangered species is the Baiji in the Yangtze River in China. The IUCN predicts that this species will be extinct within the next 10 years unless immediate action is taken to both conserve it and reverse the current rate of degradation of its freshwater habitat. Similarly, populations of Irrawaddy dolphins in the Mekong are facing a similar future with their current population put at around 60 individuals. In fact, all freshwater populations of Irrawaddy dolphins were evaluated by the UICN as ‘critically endangered’ (except for the population in Chilka Lake which has not been evaluated). The two subspecies of Susu, the Ganges River dolphin and the Indus River dolphin were evaluated as ‘endangered’ with extinction as was the Yangtze finless porpoise. The Boto, though still found throughout a large range in the Amazon and Orinoco Rivers is evaluated as vulnerable and the freshwater tucuxi is currently lacking data and has not been assessed.

The future of freshwater dolphins and porpoises appears to be bleak unless action is taken immediately to reduce the pressure on their freshwater ecosystems. They face unprecedented threats through the exploitation of freshwater river systems by people, causing high incidental mortality of dolphins and porpoises. In order to prosper, freshwater dolphins and porpoises ironically require the same conditions as people who use the river, namely, a healthy, flowing, living river.