GUWAHATI, Dec 9 – The Gangetic river dolphin (Platanista gangetica), known as shihu in Assamese, is on the verge of getting wiped out – thanks to hunting, accidental killing, habitat loss and food shortage. Once enjoying a wide distribution in the Brahmaputra and most of its tributaries, the Gangetic river dolphin in Asom now finds itself restricted to just three rivers – the Brahmaputra, the Subansiri and the Kulsi. The past few decades saw a rapid decline in its population, which, according to a survey conducted by conservation group Aaranyak in 2005, stands at just 250.
“We recorded 197 dolphins in the Brahmaputra, while 26 and 27 were found in the Subansiri and the Kulsi respectively,” Dr Abdul Wakid of Aaranyak, who is also the programme coordinator of its Gangetic Dolphin Research and Conservation Programme, told The Assam Tribune. The break-up yielded 39 calves, 47 sub-adults and 164 adults.
The survey covered 856 km of the Brahmaputra, 99 km of the Subansiri, and 76 km of the Kulsi. “We identified 82 locations in the Brahmaputra, 11 locations in the Subansiri and eight locations in the Kulsi as the existing dolphin habitats,” Dr Wakid said.
The supposed medicinal properties of dolphin oil and also its use as fish bait, the widespread use of mono-filamentous gill nets, and the lack of awareness about the urgent need to protect this elusive mammal have been largely responsible behind the steep decline of the river dolphin.
“Of the killing of minimum 14 dolphins in 2005, 12 were victims of accidental killing through gill net entanglement and two were confirmed cases poaching. Dolphins often get entangled in gill nets while attempting to catch fish from nets,” Dr Wakid said. However, though termed as accidental, such killings are sometimes intentional as fishermen use dolphin oil as fish attractant.
As part of its efforts to initiate measures to give the dwindling dolphin population a much-needed boost, Aaranyak, together with IIT-Guwahati, is working on a suitable alternative for dolphin oil. “We are trying to find out the chemical properties of dolphin oil so that an alternative could be developed,” Dr Wakid said.
Experts also believe that the ongoing Lower Subansiri hydro-electricity project at Gerukamukh and the proposed dam on the Kulsi at Umkiyam (Meghalaya) will have an adverse effect on the dolphin. Moreover, OIL’s proposed seismic survey in the Brahmaputra is also feared to cause serious disturbance to the dolphin. The State Forest Department has already moved the Union Ministry of Environment and Forests against taking any hasty steps without proper scientific study.
It is estimated that the Gangetic dolphin evolved some 20 million years ago. Its distribution is restricted to the Ganges-Brahmaputra-Meghna and Karnaphuli river system of India-Nepal-Bangladesh. Its current estimated global population is alarmingly low at less than 2,000.
Being at the apex of the ecological pyramid of the Brahmaputra river system, the Gangetic dolphin helps in maintaining equilibrium of the river ecology, and its presence indicates a healthy ecosystem of the river. It is called the ‘freshwater tiger’, as it plays the same role the tiger does in the terrestrial ecosystem.
Dolphins prefer deep water but the rapid deforestation in the riparian zones of the rivers and in the highlands of Assam and Arunachal Pradesh has been creating siltation in the riverbed, resulting in lowering of water depth. According to experts, this has led to considerable loss of habitat for the endangered animal.
Experts feel that regular survey and monitoring of the dolphin population apart, habitat management, implementation of action plan by stakeholders concerned including the Forest Department, advocacy work with governments for designating more protected areas for the dolphin, preparing guidelines for government agencies involved in riverine and waterways development, formation of dolphin rescue squads for accidentally-trapped dolphins, and campaigns for awareness and education must be taken up as a priority to save this highly-intelligent aquatic mega fauna from extinction.
