The Government of Bangladesh recently declared three new wildlife sanctuaries for endangered freshwater dolphins in the world’s largest mangrove ecosystem – the Sundarbans. The sanctuaries, which were officially declared on January 29, will protect two species of freshwater dolphins: 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 that it 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 the Bangladesh Forest Department and published in the journal Oryx in 2010. 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 freshwater river flow. It is hoped that the new wildlife sanctuaries in the Sundarbans will also provide protection for other threatened aquatic wildlife including the river terrapin, masked finfoot, and small-clawed otter.