The dolphin census going on in the Sundarbans area is indicating that the number of the mammals in the mangrove forest rivers is dropping and the experts are blaming climate change and withdrawal of fresh water from upstream.

Experts think rise of salinity in the coastal rivers, poor flow of fresh water in the Ganges river system and growing commercial activities in and around the Sundarbans are threatening the iconic animal.

The census team was lead by the eminent wildlife expert Monirul H Khan. His two-member team has completed their work in most areas of the Sundarbans. The department of forest is carrying out the census with support from the United Nations Development Programme (UNDP). 

Dolphins are among the world's most endangered mammals as per the International Union for Conservation of Nature (IUCN) red data book. Dolphin experts have been pushing the government to announce parts of the Sundarbans rivers as dolphin sanctuaries as the mangrove forest is the world's largest single habitat of freshwater cetaceans.

Even the sanctuary areas are not protected. In some areas, one side of a river is marked as protected while the other half is not. Fishermen fish in one side of the river there.  Although dolphins are not usually captured with intent, every year dozens of dolphins get entangled in fishing nets and die. They are also threatened by pollution of water transports operating in the Sundarbans.

Poor flow of fresh water from upstream, blamed on the upper riparian country, is increasing salinity of river water, resulting in dolphins disappearing, experts said. They said just a few years ago, dolphins could be sighted in all major rivers of the country. But now they can only be seen in some large rivers, like the Padma and the Karnaphuli.

source: The daily Star