Dolphins of Bangladesh Confront Changing Waters

Climate change is having a profound effect on the Sundarbans mangrove forest and adjacent coastal waters in Bangladesh, a globally important hotspot for threatened dolphins and porpoises. As sea levels rise in the Bay of Bengal from global warming, saltwater is encroaching into the mangrove forest and open estuarine habitat offshore is shrinking. Upstream water diversion in India is putting further strain on freshwater supplies. Without enough fresh water to flush away sediments, smaller channels in the Sundarbans are gradually becoming clogged with silt. As a result, critical habitat is dwindling, along with populations of fishes vital to the food security and economy of Bangladesh.

Challenges

The waterways of the Sundarbans are the meeting place of two freshwater-dependent cetaceans, the Ganges River and the Irrawaddy dolphin. The former is a purely freshwater species that ranges from Himalayan tributaries to the Sundarbans, while the latter lives in the coastal waters of the Bay of Bengal. These cetaceans rely on a delicate balance of saline and fresh water, moving upstream and downstream according to the seasonal flood cycle. With a decline in fresh water flow and the rise of sea levels, the downstream range of Ganges River dolphins and offshore range of Irrawaddy dolphins are both shrinking. These changes in marine habitat also affect Indo-Pacific humpback dolphins and finless porpoises living just outside the range of Irrawaddy dolphins. These species also depend on the ecological productivity of estuarine waters.

Goals

  • Establish a protected area network for cetaceans in Bangladesh, in order to better grasp the ecological impacts of climate change and declining freshwater supplies. This will also help us implement effective strategies to manage human-wildlife adaptation.
  • Incorporate the needs of local human communities for freshwater, fish, and crustaceans into cetacean protection plans.
  • Apply studies of the impacts of freshwater decline and sea level rise on cetaceans in Bangladesh to other areas where marine species face the same threats.

What WCS is Doing

WCS is working with the government of Bangladesh to establish a protected area network for cetacean diversity as a conservation hedge against the impacts of global climate change, declining freshwater supplies, and unsustainable fisheries. Our work is participatory, proactive, and addresses local and global threats. It is also sensitive to the needs of local people.

Beyond the Sundarbans and adjacent coastal waters, WCS recently discovered a rich variety of deep water cetaceans in a submarine canyon called the Swatch-of-No-Ground, located just 25 miles from the mangrove forest. Recent studies examining the impacts of climate change on these species indicate that the canyon’s highly productivity, cool waters could serve as a vitally important refuge for them. WCS is now working to include the Swatch as part of the protected area network.

From the Newsroom

Bangladesh Helps Threatened Dolphins Stay AfloatFebruary 14, 2012

The Government of Bangladesh declares three new wildlife sanctuaries for Ganges River and Irrawaddy dolphins. A WCS collaborative study with the Bangladesh Forest Department helped pinpoint the locations of the new protected areas.

Looking for a Good Catch? Ask the Irrawaddy DolphinAugust 4, 2006

A novel partnership between fishermen of the Ayeyarwady River in Myanmar and an endangered river dolphin guarantees a good catch for the fishermen. By establishing a protected area along a stretch of the river, the government of Myanmar is helping to safeguard this unique cultural tradition.

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