Japanese team instal hydrophones to study Irrawaddy dolphins

Bhubaneswar, Feb 5: An eight-member Japanese team, led by Prof Tamaki Ura of University of Tokyo, has successfully installed an improved design of five Hydrophone cross array system with high resolution to study the underwater behaviour of the endangered Irrawaddy dolphins in Chilka lake.

The system deployed at a selected water site with a RF-LAN connection to the base station at Chilka Development Authority(CDA) office at Satpada would now monitor the underwater movement of Irrawaddy dolphins inside the lake.

Prof Ura, who visited the lake on January 28 and stayed for a week to instal the hydrophone cross array system, told newsmen here yesterday that the new system would now monitor the swimming and other underwater behaviour of the dolphin besides their migration in the lake.

He said last year the team had installed a single horizontal line array along with a data logger and successfully monitored various locations of the concentration of the dolphins.

This time, Dr Ura said an improved design had been installed for high resolution of 360 degree coverage of the underwater movement of the Irrawaddy dolphins.

He said a controllable video camera had also been installed on the water site for visual monitoring and as a result the acoustic data would be recorded on the on side computer to be retrieved periodically for detailed analysis of the movement and underwater behaviour of the Dolphins so far unknown to the scientists.

Dr Ura said a single hydrophone could record signals up to one MHz but the five-hydrophone cross array system with high resolution would be useful for recording signal up to 2MHz. The system device, he further said, would not only study the behaviour of the dolphin, but also provide ample findings on their migration and also their rough population inside the lake.

The Japanese team had conducted static and dynamic tests of the acoustic technology during January 28-February 03 the result of which would be known only after analysing the data.

Dr Ura said the dolphins emit sonar pulses which they used as echolocation tool for finding prey and also for navigation. These sound pulses appear as ''click'' of specified signal and bandwith and could be observed with specially designed under water acoustic device.

He said there are indications that the dolphins were shifting to the outer ring of the core area and more prominently found in the narrow channel of the lake. The hydrophone, installed inside the water of Chilka, would now also study the traffic and the migration of the marine species, from Muggermukh to new mouth round the year.

UNI