A team of Japanese scientists, in collaboration with researchers in India, will undertake a study of Irrawady dolphins, inhabiting the Chilika lake in Orissa, using acoustic technology.

This is the first time that a study using such technology is being conducted in the country, Ajit Patnaik, chief executive of the Chilika Development Authority, said.

Prof Tamaki Ura of University of Tokyo, who would be leading the study team, said that small cetaceans like dolphins and porpoises emitted sonar pulses which they used for navigation and spotting of prey.

Specially designed hydrophones (an underwater acoustic device) caught these sounds as 'clicks' of a specified duration and bandwidth, he said adding such technology had been used in Japan [Images] and China on bottlenose dolphins and finless porpoises.

The India-Japan research team would use such customised hydrophones to track these 'clicks' which were emitted in a
confined beam.

Such technology was used to observe the behaviour of Chinese river dolphin 'baiji' which used its sonar pulses for
finding prey, Ura said.

Irrawady dolphin, the only known marine mammal in the Chilika lagoon, was also at the top of the food chain.

The overall health of the lagoon's ecosystem was indicated by the status of these dolphins, Patnaik said adding
if their number was growing, it could be said that the lagoon's eco-system was thriving.

In view of the ongoing efforts of CDA to improve the eco-system, use of advanced and automated technology could
assist in the survey of the dolphins, Ura said.

The Japanese team, led by Ura, would bring along the two survey technologies and would be assisted by Prof R Bahl of
IIT, Delhi and Dr Sandeep Behera of Worldwide Fund for Nature, Delhi.

The 5-hydrophone system was proposed to be used for initiating underwater observation of irrawady dolphins in
Chilika.

It was expected that movements of several dolphins in a group could be independently monitored, he said.

Chilika is believed to have about 80 such dolphins most of which could be viewed near Satapada in Puri district. Ura said a miniature acoustic data logger --12 centimetres in length and 2 centimetres in diameter -- would also be tested. The system was expected to provide not only the migration timing but also the rough number of animals that pass by the data logger system.

Ura would be assisted by Dr Tomonari Akamatsu, Harumi Sugimastu, Junichi Kojima, Hideyuki Takahashi, Takashi
Sakamaki and Tomoki Inoue.