Seismic survey will harm dolphins and whales, say greens

PUBLISHED : Sunday, 22 March, 2009, 12:00am
UPDATED : Sunday, 22 March, 2009, 12:00am

A seismic survey about to begin in the waters of Southeast Asia will harm and possibly kill dolphins and whales, green groups say.

Hong Kong celebrated its first known sighting of a humpback whale last week. But the groups warned that the arrival of the Marcus G. Langseth survey vessel could endanger already threatened marine mammal populations in the region.

Organisers of the Taiwan Integrated Geodynamics Research survey have defended the programme, which aims to better understand the fault lines around the island that cause earthquakes and occasionally deadly tsunamis.

Samuel Hung Ka-yiu, director of the Hong Kong Cetacean Research Project and chairman of the Hong Kong Dolphin Conservation Society, questioned the need for the survey, which would see the Langseth towing high-powered air guns firing pulsed sounds at high volume at the seabed. 'In our region a lot of cetaceans are endangered so we need to be very careful we don't harm them any more than necessary,' he said.

Because of the suspected link between surveys and injury to marine mammals, permission from the American government was required.

Documents supporting the application for a permit suggest that in shallow water the sound of the air guns detonating will be at a level of 190 decibels - equivalent to standing next to the space shuttle launch pad during takeoff - out to 2.2km.

Mitigation measures include having spotters permanently on duty and ramping up the noise incrementally to give the animals a chance to move out of the area.

A spokeswoman for the survey organisers, Columbia University's Lamont-Doherty Earth Observatory, said: 'There is no documentation that links our operations to harming marine life.'

Recent research showed marine mammals did not begin to experience hearing damage until noise levels were 190 decibels or louder. 'Animals are exposed to sounds no louder than 180 decibels,' she said.

The observatory had taken the concerns seriously, she said, and had redrawn its survey plan so most of the work would be in deeper water, where sound dissipates much faster.

Lee-Ann Ford, president of Linking Individuals for Nature Conservation, said: 'In the case of the pink dolphins, they have no small islands or other barriers to hide from the noise. That level of exposure threatens the entire population with sound levels that can result in serious injury [such as deafness] or death.'

Naomi Roase, senior scientist at Humane Society International, said the observatory's lack of marine-mammal experts was putting the region's cetacean population at risk.