Sonar implicated in whale stranding

SONAR STRANDING: A tour operator has expressed concerns about the increased use of sonar following the stranding of a number of Gray's beaked whales at Taupo bay.

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Dolphin tour operator John Chisholm of Mangonui, who watched last week’s stranding of three Gray’s beaked whales at Taupo Bay, says he has noticed a change in the behaviour of dolphins this summer and he is concerned that use of low frequency sonor could be disorientating whales and dolphins in the South Pacific.

Samples of two adult females and a juvenile Gray’s beaked whale were taken by Ngatiwai and AUT research officer Emma Beatson, before the dead whales were buried at Taupo Bay.

Department of Conservation officer Mita Harris says this species does not strand often.

The Gray’s beaked whale – mesoplodon grayi – lives in the Southern Hemisphere. Strandings of more than one beaked whale at the same time are said to be uncommon.

Hearing is a primary sense for whales, dolphins, and other marine species, and international evironmental groups have raised concerns about noise pollution at sea, including military sonar, oil-and-gas surveys, and noise from commercial ships.

It is argued that there is a link between the use of military sonar, which blasts vast areas of the oceans with underwater noise, and the stranding of cetaceans, particularly beaked whales.

Military active sonar systems put out intense sound to detect and track submarines and other targets.

International bodies, including the European Parliament and the International Whaling Commission have begun to address the problem, urging that nations work together. Low-frequency sonar, linked to a growing number of whale strandings worldwide, is said to travel hundreds of miles at intensities strong enough to affect marine mammals, causing them to abandon or avoid traditional habitats.

According to the the International Whaling Commission, evidence linking sonar to a series of whale strandings in recent years is ‘very convincing and appears overwhelming’.

Northland whale and dolphin expert Wade Doak says whether US Navy transmissions would affect our coast is a moot point. "But we don’t know. I wouldn’t dismiss it."

This month a federal court in San Francisco issued a preliminary injunction limiting the area in which the US Navy may train with the low-frequency sonar system SURTASS LFA – Surveillance Towed Array Sonar System Low Frequency Active Sonar.

The lawsuit was filed by a coalition of conservation organisations led by the Natural Resources Defense Council, which has embarked on a global campaign to regulate active sonar systems.

Scientists have testified that, under certain oceanic conditions, sound from a single LFA system could be detected across entire oceans.

The Royal New Zealand Navy does not use low frequency sonar.

- © Fairfax NZ News