Ganges river dolphin in danger of extinction
International Union for Conservation of Nature (IUCN) has branded it as a 'critically endangered' species.
The Ganges river dolphin, locally known as Shushuk, is facing serious threat of extinction due to increasing human intervention like water pollution, fishing and intrusion into their habitats..Already, the International Union for Conservation of Nature (IUCN) has branded it as a 'critically endangered' species.
"They live throughout the Padma, Meghna, Jamuna, Karanphuli and Sangu rivers and were frequently seen at ferry crossings but now the frequency of their visibility is falling," Dr Md Anwarul Islam, Professor of the Zoology Department of Dhaka University, told The Independent yesterday.
He said that the alarming rise of pollution in rivers posed a serious threat to the survival of Shushuk. "Pollution of the Buriganga river along with other rivers of the country has "driven" the dolphins away. They cannot adjust to the filthy dirt and have shifted to other areas on the lookout for fresh water. As Shushuks are mammals, they need to come out of the water frequently to take a breath", he said.
Experts feel that the climate change is having a profound effect on the Sundarbans mangrove forest and the 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", Jahangir said.
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 range from the 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 the 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.
Explaining the threat of fishing with small nets, also known as "current net", he said that when fishermen use fishing gears made of such nets to catch small fishes, Shushuks also get caught. Sometimes the fishermen cut the fins of Shushuks to save their nets and the innocent mammals cannot swim anymore.
He said that immediate measures to save the rivers from water pollution and restoration of the depth of rivers were needed to save Shushuk from becoming extinct."The Ganges river dolphin or Shushuk has a long beak, a stocky body, and large flippers. Its eye lacks a lens, and the dolphin is sometimes referred to as being blind, although its eyes do seem to function as a direction-finding device. It measures 1.5 - 2.5 m (4.9 - 8.2 ft) in length and weighs up to 90 kg", he said adding that it occurs only in fresh water in Bangladesh and India, where the rivers flow slowly through the plains, as well as in Nepal, where the dolphin can be found in relatively clear water and rapids.
The Ganges river dolphin lives not only in the main channels, but also, during the flood season, in tributaries and flooded lowlands. Currently, shushuk is found in the Ganges-Brahmaputra-Meghna and Karnaphuli-Sangu river systems of Bangladesh and India.
The linear extent of its distribution in the Ganges mainstream appears to have diminished by some 100 km (62 mi) since the 19thcentury, and even larger amounts of tributary habitat have been lost due to reduction in water flow below irrigation barrages. Its habitat is severely fragmented, and additional barrages continue to be built. "Construction of 50 or more dams and barrages within the Ganges river dolphin's historic range has drastically altered its habitat and fragmented the population" said Md Jahangir Alam, project director of the Bangladesh Cetacean Diversity Project (BCDP).
Jahangir who has been engaged in research on Shushuk for long years said approximately 3,500 km (2200 mi) of embankments have been constructed along the main channel of the Ganges and its tributaries. Embankments interrupt access to spawning habitat for floodplain-dependent fishes and eliminate eddy counter-currents where the dolphins spend much of their time, he added.
He said that in its latest survey in 2004, BCDP found 225 shushuk in the Sundarbans and 125 in the Karnaphuli river.
Dredging and the removal of stones, sand, and woody debris also compromise the ecological integrity of the riverine environments, especially in small tributaries.
Earlier, in 2001 a survey on distribution of Shushuks in each square kilometre river area found 0.76 individual in each km in the Karnaphuli-Sangu area, 1.4 individual/km in the Sangu below the Dohazari Bridge, 0.81 individual/km in the middle reaches of the Ganges mainstream, 0.24 individual/km in the middle reaches of the Jamuna, 0.30 individual/km in the Kalni-Kushiyara river, 1.5 individual/km in the Ganges River mainstream between Maniharighat and Buxar and 0.09 individual/km in the Sundarbans.
"They live throughout the Padma, Meghna, Jamuna, Karanphuli and Sangu rivers and were frequently seen at ferry crossings but now the frequency of their visibility is falling," Dr Md Anwarul Islam, Professor of the Zoology Department of Dhaka University, told The Independent yesterday.
He said that the alarming rise of pollution in rivers posed a serious threat to the survival of Shushuk. "Pollution of the Buriganga river along with other rivers of the country has "driven" the dolphins away. They cannot adjust to the filthy dirt and have shifted to other areas on the lookout for fresh water. As Shushuks are mammals, they need to come out of the water frequently to take a breath", he said.
Experts feel that the climate change is having a profound effect on the Sundarbans mangrove forest and the 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", Jahangir said.
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 range from the 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 the 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.
Explaining the threat of fishing with small nets, also known as "current net", he said that when fishermen use fishing gears made of such nets to catch small fishes, Shushuks also get caught. Sometimes the fishermen cut the fins of Shushuks to save their nets and the innocent mammals cannot swim anymore.
He said that immediate measures to save the rivers from water pollution and restoration of the depth of rivers were needed to save Shushuk from becoming extinct."The Ganges river dolphin or Shushuk has a long beak, a stocky body, and large flippers. Its eye lacks a lens, and the dolphin is sometimes referred to as being blind, although its eyes do seem to function as a direction-finding device. It measures 1.5 - 2.5 m (4.9 - 8.2 ft) in length and weighs up to 90 kg", he said adding that it occurs only in fresh water in Bangladesh and India, where the rivers flow slowly through the plains, as well as in Nepal, where the dolphin can be found in relatively clear water and rapids.
The Ganges river dolphin lives not only in the main channels, but also, during the flood season, in tributaries and flooded lowlands. Currently, shushuk is found in the Ganges-Brahmaputra-Meghna and Karnaphuli-Sangu river systems of Bangladesh and India.
The linear extent of its distribution in the Ganges mainstream appears to have diminished by some 100 km (62 mi) since the 19thcentury, and even larger amounts of tributary habitat have been lost due to reduction in water flow below irrigation barrages. Its habitat is severely fragmented, and additional barrages continue to be built. "Construction of 50 or more dams and barrages within the Ganges river dolphin's historic range has drastically altered its habitat and fragmented the population" said Md Jahangir Alam, project director of the Bangladesh Cetacean Diversity Project (BCDP).
Jahangir who has been engaged in research on Shushuk for long years said approximately 3,500 km (2200 mi) of embankments have been constructed along the main channel of the Ganges and its tributaries. Embankments interrupt access to spawning habitat for floodplain-dependent fishes and eliminate eddy counter-currents where the dolphins spend much of their time, he added.
He said that in its latest survey in 2004, BCDP found 225 shushuk in the Sundarbans and 125 in the Karnaphuli river.
Dredging and the removal of stones, sand, and woody debris also compromise the ecological integrity of the riverine environments, especially in small tributaries.
Earlier, in 2001 a survey on distribution of Shushuks in each square kilometre river area found 0.76 individual in each km in the Karnaphuli-Sangu area, 1.4 individual/km in the Sangu below the Dohazari Bridge, 0.81 individual/km in the middle reaches of the Ganges mainstream, 0.24 individual/km in the middle reaches of the Jamuna, 0.30 individual/km in the Kalni-Kushiyara river, 1.5 individual/km in the Ganges River mainstream between Maniharighat and Buxar and 0.09 individual/km in the Sundarbans.
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