Irawaddy dolphins discovered in Bangladesh
Updated
Researchers have found the world's largest population of rare Irrawaddy dolphins in the rivers and coastal mangroves of Bangladesh.
The shy grey dolphin was thought to be found only in small -- and often critically endangered populations across Asia, but this find gives new hope to the survival of the species. However, conservationists warn that global climate change and declining supplies of freshwater coming into the Bangladesh delta could threaten the Irrawaddy dolphin.
Presenter: Liam Cochrane
Speakers: Rubaiyat Mansur Mowgli, Guide; Brian Smith from the Wildlife Conservation Society
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COCHRANE: At the mouth of the Ganges River, lies the world's largest stretch of mangroves, the heritage-listed Sundarbans Reserve Forest. While on shore it's the home for the rare Bengal tiger, the area of mangroves and coastal waterways is teeming with dolphins and porpoises. For years, local guide Rubaiyat Mansur Mowgli showed tourists the thin-snouts of Ganges dolphins up river and, further towards the sea, the finless porpoises and Indo-Pacific humpback dolphins. But in between, in the mix of fresh and salty water, lived another seldom-seen species - the Irrawaddy dolphin.
Mr Mowgli became the principle researcher of a study mapping the Irrawaddy population and after five years of careful spotting says almost 6,000 Irrawaddy dolphins live along Bangladesh's coast.
MOWGLI: And this was amazing because all of the other populations of those species are very small, less than 100 individuals - in the Philippines in Malampaya Sound, and in Vietnam, Cambodia, Lao in the Mekong river, and in Indonesia - all these countries have Irrawaddy dolphins but in very small numbers, the total for the country is very small compared to ours.
COCHRANE: In contrast to these small pods of dolphins, the study in Bangladesh found 450 creatures just in the Sundarbans mangrove reserve and another 5,400 scattered along the coast. It seems the Bangladesh delta has just the right combination of brackish water and deep holes in which the Irrawaddy dolphins thrive. But, like in other countries, Bangaldesh's dolphins are threatened by fishing.
MOWGLI: The immediate population threat that we can identify is the entanglement with gill nets. There is a lot of gill net fishing going on in the coastal waters of Bangladesh and sometimes the nets are like 2km long and the dolphins cannot pick them up.
COCHRANE: The other possible threats to the Bangladesh's dolphins are ones that affects Bangladesh's humans population too - less fresh water and rising seas. Brian Smith works for the Wildlife Conservation Society on a program to conserve dolphins, porpoises and whales in Asia.
He says the dolphins' habitat risks being squeezed - from one side by rising sea waters due to global warming, and from the other side by rivers running thicker with sediment, which is caused by diversions upriver in the Ganges for irrigation and navigation.
As a result, the Irrawaddy dolphins could act as a kind of 'canary in the mine' for the changing waterways.
SMITH: We've really found that they're quite informative in terms of the impact of both climate change and declining freshwater supplies, especially in the Sundarbans, because the Sundarbans Mangrove Forest is really where the fresh water meets the sea.
COCHRANE: Mr Smith also says that just because a thriving population of Irrawaddy dolphins has been found in Bangladesh, doesn't mean we should forget efforts to conserve them and their fragile habitats.
SMITH: You know as a conservation biologist I spend a lot of time what I call 'ambulance-chasing', when things become down to critically low levels. Once the populations become depleted to such an extent its very difficult to save them, so I think its equally important to put our emphasis on really conserving population where we still have good numbers.
