On the eve of World Water Day, WWF warns that Asia's river dolphin populations are in severe decline due to polluted waters, dams and entanglement in fishing nets and has launched an initiative to save some of the world's most threatened mammals.

According to the global conservation organization, this is all the more worrying as river dolphins are key indicators of a river's health and of the availability of clean water for the people living along its banks.

WWF lists industrial, agricultural and human pollution, as well as the use of dams, which restrict the dolphins movement as some of the major threats facing the aquatic mammal. Accidental catches by fishermen are also contributing to the decline of dolphin populations.

River dolphins are the watchdogs of the water, said Jamie Pittock, Director of WWF's Global Freshwater Programme. The high levels of toxic pollutants accumulating in their bodies are a stark warning of poor water quality. This is a problem for both dolphins and the people dependent on these rivers.

Latest evidence shows that the Yangtze River dolphin is particularly threatened with only 13 individuals left in Chinas largest river. Another study by WWF-India revealed that there are fewer than 2,000 Ganges River dolphins along the 6,000km stretch of the Ganges and Brahmaputra river system. A similar number of Irrawaddy dolphins remain in Asia-Pacific waters. While in Pakistan, there are no more than 1,100 dolphins scattered in five populations.

River dolphins swim in some of the worlds most densely populated river basins, including the Ganges and Indus river basins, where one tenth of the worlds people live.

Clean water is not only vital for the survival of the river dolphin, but also for the quality of life for millions of the worlds poor, added Jamie Pittock. Conserving biodiversity and alleviating poverty reduction are inextricably linked.

WWF is working with authorities and local people along the Ganges, Yangtze and Indus rivers to improve water quality and dolphin habitat. For example, through the WWF River Dolphin Conservation initiative, local communities are being encouraged not to pollute the river with household detergents and to prevent toxic run-off by using natural fertilizers, such as cow manure. In the Ganges, such an initiative has increased dolphin numbers from 22 to 42 over the past decade along a 164km stretch of the river.

With one of the UNs Millennium Development Goals (MDGs) being to halve the number of people without safe water supplies and sanitation by 2015, WWF is calling on governments, local communities, water management agencies and investors to protect areas of high biodiversity to ensure that they provide clean water for people and nature.