New hope for Irrawaddy dolphins
A new study has shown that approx 6,000 Irrawaddy dolphins are alive and swimming in Bangladesh waters. Researchers found the dolphins living in the freshwater regions of Bangladesh's Sundarbans mangrove forest and nearby waters in the Bay of Bengal.
The largest known populations of Irrawaddy dolphins to date have numbered in the low hundreds or less and until this new Bangladesh population was found, figures from the International Union for Conservation of Nature (IUCN) estimated the Sundarbans population to be around 450. The discovery of a new population is an important finding as scientists and conservation groups do not know how many Irrawaddy dolphins remain across south and south-east Asia and this particular species, were listed in 2008 as "vulnerable" on the IUCN's "red list" of endangered species due to declines in known populations. The results of the study were announced recently at the world's first international conference on marine mammal protected areas in Maui, Hawaii, and published in the Journal of Cetacean Research and Management.
Scientists estimated the numbers of the new Bangladesh population using a technique called distance sampling – taking a boat along plotted grid lines and counting the numbers of animals seen, accounting for how many are above or below the surface and whether the same animal has been counted twice. The team covered 1,000 sq km of water during the survey in 2004.
However the dolphins are still under threat and are becoming increasingly threatened by accidental entanglement in fishing nets. Declining freshwater supplies also pose a threat – from upstream water diversions such as dams and by rising sea levels caused by climate change that will see the loss of freshwater habitats. Conservations groups are now asking Bangladesh authorities to establish a sanctuary for the dolphins in the Sundarbans mangrove forest. There is plenty of food in the area for the animals to eat but what is now needed is to restrict fishing in the area to protect the dolphins.
The Irrawaddy dolphin grows to some 2-2.5 metres in length (6.5-8ft) and lives in large rivers, estuaries, and freshwater lagoons in south and south-east Asia.
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