New Hope for Threatened Freshwater Dolphins in Asia

The Government of Bangladesh recently declared three new wildlife sanctuaries for endangered freshwater dolphins in the world's largest mangrove ecosystem -- the Sundarbans, according to the Wildlife Conservation Society (WCS) whose conservation work helped pinpoint the locations of the protected areas.

The sanctuaries, which were officially declared on January 29, will protect the last two remaining species of freshwater dolphins in Asia: the Ganges River dolphin and the Irrawaddy dolphin. Although there is no global population estimate for either species, both have disappeared from major portions of their range. However, both species occur in the Sundarbans in sufficient numbers, which may serve as a global safety net for preventing their extinction.

The three wildlife sanctuaries safeguard 19.4 mi (31.4 km) of channels with a total area of 4.1 sq mi (10.7 sq km). The locations and sizes of the sanctuaries in the Sundarbans were determined according to a study conducted by WCS and Bangladesh Forest Department. The study found that the habitat of Ganges River and Irrawaddy dolphins were clumped in waterways where human activities are most intense.

The dolphins are threatened by fatal entanglements in fishing gear, depletion of their prey from the enormous by-catch of fish and crustaceans in fine-mesh "mosquito" nets used to catch fry for shrimp farming, and increasing salinity and sedimentation caused by sea-level rise and changes in the availability of upstream freshwater flow.

News of the declared sanctuaries is particularly welcome considering the recent extinction of the Yangtze River dolphin whose last confirmed sighting was in 2002. 

Freshwater dolphins are among the most threatened wildlife on earth because their habitat is highly impacted by human activities, including dam construction and unsustainable fisheries. In addition to conserving globally important populations of freshwater dolphins, the new wildlife sanctuaries in the Sundarbans will provide protection for other threatened aquatic wildlife including the river terrapin, masked finfoot and small-clawed otter.

Bangladesh has been recognized as a "hotspot" for cetaceans, the scientific grouping of dolphins, whales and porpoises. In April 2009, the Wildlife Conservation Society announced the discovery of the world's largest population of nearly 6,000 Irrawaddy dolphins in the country. A portion of this population shares habitat with the endangered Ganges River dolphin, whose range extends all the way upstream to the shadow of the Himalayas in Nepal.

Starting on February 18, 2012, WCS, through its Bangladesh Cetacean Diversity Project, will bring a boat-based dolphin exhibition called the "Shushuk Mela" to local communities bordering the Sundarbans mangrove forest. This month-long traveling exhibition will raise awareness about the new wildlife sanctuaries and engage local fishermen and other community members in discussions on adaptive management needed to ensure human-dolphin coexistence.