Hear the dolphins sing
- Japanese water acoustics technology on Brahmaputra
Guwahati, Jan 5: Japanese underwater acoustics technology, used for detection of Gangetic dolphins, is now being planned for the Brahmaputra.
Aaranyak, a biodiversity conservation society of theNortheast, which had earlier conducted two surveys in 2005 and 2008, now plans to use Japanese technology to increase the detection of dolphins.
“Direct sighting has been useful but we would like to increase the detection as all dolphins cannot be sighted visually. The underwater acoustic device or hydrophone, which measures the clicking sounds emitted by the dolphins, can helpin detection,” said Abdul Wakid, International Union for Conservation of Nature (IUCN) dolphin specialist and programme head of Gangetic Dolphin Research and conservation programme of Aaranyak.
Sound frequencies produced by dolphins are picked up by hydrophone and observers on land can view the real time location displayed on a PC over a wireless connection.
The third survey, to be held on the Kulsi, Subansiri and Brahmaputra mainstream is being planned before the monsoon.
The state forest department has to give its permission before the survey can be conducted.
The Gangetic river dolphin (Platanista gangetica gangetica) is primarily an inhabitant of the Ganga and Brahmaputra river systems of India and Bangladesh. At present there are less than 2,000 dolphins surviving in the world.
The species has been declared a national aquatic animal by the Centre on October 5, 2009.
Wakid has been working on Irrawaddy dolphins in Chilika lake with Tomonari Akamatsu, an acoustic expert from the National Marine Fisheries Research Institute, Japan, as well as an IUCN recognised cetacean expert. The acoustic technology has been testedon the Ganga and Chilika lake and the results have been good.
The Peter Scott Fund of IUCN, which had helped carry out the dolphin survey on the Brahmaputra in 2008, had said in its report that there is a planned collaborative project between the Japanese and Indian teams to deploy refined acoustic devices in the river.This objective will hopefully be fulfilled in the near future.
Brahmaputra river system in Assam has been identified as one of the last habitats of the species by scientific communities. Although there was a gradual decline of the species in last few decades, currently the population has shown an increase. In the 1993, 1997 and 2002 surveys, altogether 266, 218, and 198 dolphins were recorded in the Brahmaputra mainstream.
However, in the 2005 and 2008 surveys, Aaranyak has recorded 197 and 212 dolphins respectively on the same river stretch (Assam-Arunachal border to India-Bangladesh border).
A community-based dolphin conservation network has been formed under the Gangetic Dolphin Research and Conservation Programme to monitor important dolphin habitats. The mortality rate of the species has declined from 16 deaths in 2008 to five in 2009 because of intensive monitoring.
“Management authorities, organisations working for conservation and local communities need to work more closely, collaboratively and effectively, since the threat factors (accidental killing through fisheries entanglement, poaching) on dolphins are still very intense,” Wakid said. Wildlife expert Anwaruddin Choudhury feels though the population has stabilised, poaching is still a concern.