Noisy waters

Published: Wednesday 15 April 1998

It was long suspected that communication among whales suffered due to the use of sonar by the world's navies. Alexandros Frantzis of the University of Athens has recently come out with his findings that say whales may be suffering "collateral damage" due to sonar waves from naval vessels as they use their own form of sonar to navigate and hunt. They also use sonar-like low frequency sound for communicating with each other. This is commonly known as whale song. Frantzis has studied Cuvier's beaked whale off Greece's west coast. Whales either get stranded individually or -- sometimes -- as a group. Normal mass strandings occur when a group of whales follow a leader that misnavigates. But in May 1996, Frantzis saw 12 beaked whales stranded as individuals along a 40-km beach in the duration of two days. This is very rare. Sure enough, Frantzis found that a NATO (North Atlantic Treaty Organisation) vessel was in the area at the time, testing a sonar that produces extremely loud, low-frequency sound. The maximum out put was 230 decibels. Jumbo jets do not go over 100 decibels. Frantzis found that three similar strandings in the Canary Islands were also linked to military manoeuvres ( The Economist , Vol 346, No 8048).

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