Study attempts to save endangered river dolphins

Intensive activities of sand mining and fishing, coupled with various forms of pollution are driving the Gangetic dolphin from its larger habitat in the Brahmaputra River into its tributaries and closer to extinction, an ongoing study has found.

A Goan marine zoologist, Manoj Borkar and experts from the University of Gauhati have jointly initiated a field study in the country’s biggest river and some tributaries to assess the danger to the dolphin’s habitat.

“The exploratory survey is aimed at understanding the ecology and conservation status of the freshwater mammal,” says Borkar.

There are only four obligate freshwater dolphin species in the world. One is in India, while other relatives are in the Amazon River (the dolphins are called Boto here), Yangtze River in China (Baiji) and the Indus River in Pakistan (Bhulan). According to conservative estimates, the global population is said to be less than 2,000 individuals.

The decline in the river dolphins’ numbers set an alarm worldwide. The International Union for Conservation of Nature (IUCN) revised the conservation status from vulnerable in 1991 to endangered in 1996.

“The distressing change induced me to propose a joint study to S K Borthakur, professor at the University of Gauhati, and he readily agreed,” Borkar says.

The union ministry of environment and forests (MoEF) has also realized the extreme danger to river dolphins in the Ganga and Brahmaputra. “The Gangetic dolphin is high on the conservation priority and MoEF has elevated it to the status of the national aquatic animal, though the fact itself is little known,” says Borkar.

Referred variously, depending on the region-‘sihu’, ‘susu’ and ‘hihu’ in North India-the dolpin was initially the state animal of Assam, and rightly so.

“During my childhood, I would see lots of dolphins on the banks of the Brahmaputra in Guwahati, but now you can’t see a single one,” Borthakur told TOI from Assam.

The habitat of the peculiar mammal has been drastically altered and it is nowprimarily found only in small numbers in a few states. These include Bijnor in Uttar Pradesh, Chambal in Madhya Pradesh, Vikramshila sanctuary in Bihar and Brahmaputra River in Assam. As of now, the distribution in the Brahmaputra itself is restricted.

“The sightings are easier in the tributaries, especially a stretch of Kulsi River, but there may be hardly 30 individuals there,” says Borkar.

The pollution levels in the Brahmaputra River and massive human intervention has affected the dolphin’s larger habitat. “They are very sensitive to pollution and the spill of sewage and other urban wastes has disturbed their habitat,” says Borthakur, a reputed ethnobotanist.

The Gangetic dolphin is regarded as an intelligent mammal with discreet communication skills, emitting a whistle-like sound. “Unlike its marine cousin or relative, by virtue of its small size and pinkish grey shade of the body, extremely reduced dorsal fin and vestigal eyes, the river dolphin is almost blind,” Borkar says.

Full report: Times of India

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