(West Australia) Defence department says whale noises interfere with submarines

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Lowdown on noisy whales

The West Australian

28/10/2002

http://www.thewest.com.au/20021028/news/state/tw-news-state-home-sto76663.ht

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By Carmelo Amalfi

 

 

DEFENCE Department money will be used to count blue whales in WA's

underwater grand canyon west of Rottnest because their noise interferes with

submarine communications.

 

WA researchers are heading to the deep waters to track blue and pygmy blue

whales which congregate to feed in the canyon each year from December to

May.

 

Perth Canyon - also called the Perth Trench and Rottnest Trench - is about

30km west of Rottnest. It cuts into the continental shelf, dipping from

depths of 200m near the coast to a vast, 4km-deep plain shared by the

endangered whales and submarines on exercise.

 

Over coming months, the WA study group will visit the canyon to track whales

feeding on swarms of krill and other crustaceans.

 

The team, funded by the Defence Department and Environment Australia, hopes

to define the canyon's importance to blue whales and predict when, where and

how many whales congregate as a way to avoid close encounters with

submarines. Program manager Rob McCauley said the navy was serious about its

environmental obligations.

 

" The blue whales interfere with their own operations, " he said. " They make

enormous amounts of noise that can mask (submarines') underwater acoustic

activities. "

 

Dr McCauley said the project evolved from reports of blue whale sightings

along the south coast.

 

Combined with previously suppressed Russian data on WA whale catches, former

WA Museum director John Bannister persuaded the International Whaling

Commission in 1994 to fund two voyages along the southern coast to look for

blue whales, which are about 30m long. One ship sailed south out of

Fremantle, skirting the canyon, and ended up in Portland, Victoria, without

spotting a whale. The second vessel headed directly west off Fremantle and

spotted up to five a day.

 

Dr McCauley said aerial and passive acoustic surveys and small boat studies

carried out in 1999 and 2001 confirmed the canyon was a favoured habitat for

the pygmy blue whale.

 

This sub-species, which reached about 25m in length, were sighted nearly all

year round off Exmouth, Geraldton and Jurien Bay.