About The Species
Ganges river dolphins are one of six freshwater dolphins in the world. Their closest relative is the Indus river dolphins. However, they are the oldest among these, having evolved 16-23 million years ago. They are blind and occupy the waters in the Indian subcontinent – the Ganges-Brahmaputra-Meghna-Kanaphuli-Sangu river systems.
Current status and distribution
Almost 80% of the Ganges river dolphins inhabit the Brahmaputra and Ganga river basins in India. Dolphin ranges into most of the large tributaries in the Ganga Basin: Chambal, Ramganga, Yamuna, Gomti, Ghaghara, Rapti, Gandak and Kosi. In the Brahmaputra Basin includes Tista, Adadhar, Champamat, Manas, Bhareli, Subansiri, Dihang, Dibang, Lohit, Disang, Dikho and Kulsi rivers.
Surveys have confirmed extirpation of populations from many of the tributaries in the last 10-20 years, viz., Son, Ken, Betwa, Punpun and Barak.
The numbers of these Ganges river dolphins were reported to lie somewhere around “tens of thousands” in the 19th century, which were reported to have dropped to lie between 4000 and 5000 towards the end of the 20th century. Currently the estimate lie between 3000-4000 individuals.
Biology and evolution of dolphins
Platanista fossils have been found in the marine environment. However, after the marine dolphins evolved and took over, Platanista adapted to the fresh water systems and occupied the waters of the Indian subcontinent – the Ganges-Brahmaputra-Meghna-Karnaphuli-Sangu river systems.
Threats and concerns
Threat assessment is crucial to draw a strong conservation action plan for the Dolphins and the associated species. It has been found that exploitative fishery practices, hunting dolphins and other human activities are causing mortalities in the target species as well as degrading the stability of the population of these species.
Associated aquatic fauna
Ganges river dolphin habitats coincides with the habitat of multiple species such as fishes, birds, turtles and otters.
Water and air quality
River Ganges and Brahmaputra are the two primary habitats of Gangetic river dolphins in India and, both the rivers have different sources of pollution.