Japanese use sub to track down whales

[Guest guest]

New Scientist June 30, 2001 This Week, Pg. 25

 

Find that whale!

 

Peter Hadfield (Tokyo)

 

A seagoing robot can home in on particular species

 

AN UNMANNED submarine has been developed by Japanese marine

engineers to automatically track down and follow pods of

whales and shoals of tuna. While its inventor insists the

vessel is intended for research, it is likely to alarm

conservationists worried that it might help Japan's

controversial " scientific " whalers locate their prey.

 

The 3-metre-long seagoing robot has four underwater microphones

or hydrophones mounted on the " wings " that control its

motion through the water. From differences between sounds

picked up by each hydrophone, an on-board computer works

out where the sound is coming from. And by comparing the

sound with stored recordings of various types of whale or

tuna, it can home in on a particular species.

 

Once the sub has located a target, it can automatically follow a shoal

or

pod at a leisurely 1 to 2 knots (2 to 4 kilometres per

hour) for 10 hours. In field tests near Japan's Kerama

Islands in March, researchers led by Tamaki Ura of the

Institute of Industrial Science at Tokyo University

successfully used the sub to track a pod of humpback whales.

 

The tests began when hydrophones hanging from the research

ship located a distant pod of whales. The sub then dived to

about 50 metres and switched off its electric motors so

that they would not drown out the whales' faint song. " The

submarine automatically followed the sound and after an

hour and a half came within 50 metres of the whale, " says

Ura.

 

The sub is intended for research, not hunting, Ura

insists. Asked if it might be used in Japan's scientific

whaling programme in Antarctic waters, which critics say is

a cover for the commercial exploitation of minke whales, Ura

said: " I know very little about the minke whale, so I can't

answer. " It's hard to track sea creatures using

conventional diving equipment because it either has to be

manned, or tethered to research ships. " For intensive

observation of whales, it is necessary to follow them

closely as they dive, " says Ura. Next, he plans to create a

version of the sub geared for surveying underwater

volcanoes. The system for tracking whales and tuna will be

presented at an international sea mammal symposium in

Vancouver in November. See: http://www.newscientist.com