Thursday, December 08, 2005

Tagging may help find out if great white sharks are able stalkers

GREAT White sharks may soon be tracked along the metropolitan coastline using sonar or satellite technology.Fisheries Director Will Zacharin yesterday revealed a feasibility study was being conducted into the initiative, which would also ultimately involve Victoria, Tasmania and Western Australia.

The technology could enable experts to tell if a single rogue shark has been responsible for recent attacks off Adelaide's coast.

Shark expert Andrew Fox said: "Tagging them so they can be positively identified is about the only way of telling if the same shark has come back to the same area."

Satellite tagging had already proven successful in a scientific study conducted by the CSIRO last year in which four Great White sharks were tracked after they were tagged at the Neptune Islands, 80km south of Port Lincoln.

Sonar tagging had also been a success at the Neptunes with underwater sonar buoys recording the movements of tagged sharks over two years.

"We are looking at expanding a tagging program across southern Australia," Mr Zacharin said.
"The project is being developed. It will be a combination of satellite and acoustic tags."

New technology had made the tags more reliable and longer lasting with some now lasting more than two years.

Future testing would involve placing sonar tracking stations at various locations - including along the metropolitan coastline - to monitor a tagged shark's location.

"It is already done at the Neptunes on a small scale, but we are looking at expanding that program considerably. We are rapidly assessing the technology, the feasibility and the cost," Mr Zacharin said.

He revealed that since January 1 there had been 44 shark reports to the Fishwatch hotline.
Many had been confirmed, but others had been unfounded or were dolphins or seals.

He said the increased public awareness of sharks and the willingness to report sightings was partly attributable to the volume of calls to the hotline. The latest was an incident involving a Great White off Middle Beach, north-west of Adelaide, last week in which a shark mouthed a boat's outboard motor after eating a berley bag used to attract fish.

Shark expert Rolf Czabayski said yesterday such interaction was inevitable because of the methods used by fishermen to attract fish.

It would be "impossible to tell" if the shark sighted off Middle Beach last week had frequented the metropolitan coastline previously, he said. Many sharks he had encountered had similar wounds and markings near the mouth.


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