Friday, September 22, 2006

Tagging provides great info on sharks

THE white pointer Columba tagged off Pearson Island in June this year has provided researchers with an insight into the scope the sharks travel.

The shark swam straight for the Western Australian coast.

Commonwealth Scientific and Industrial Research Organisation (CSIRO) marine researcher Russell Bradford said it was the first shark that had been tracked by satellite that had moved north along the WA coast.

"We have known for some time that white sharks move up the WA coast as far as the Carnavon-NW Cape region but we do not know why they do this, nor do we have a good detailed track of how they get there," Mr Bradford said.

The 3.5 metre Columba was the only white shark that was tagged by the CSIRO researchers in the June project and follows on from 10 taggings by the CSIRO since 2000.

In November 2004 four great white sharks were tagged and their travels posted on the internet.
It added to information found from six other sharks tagged by the CSIRO since 2000.

Three of the November-tagged sharks swam along the coast past Venus Bay and Streaky Bay to get to the Great Australian Bight.

Another shark swam the opposite direction along the middle of Spencer Gulf just northwest of Wardang Island.

The travels of the four sharks, named Bomber, Michael, Sam C and Rolf for three months over summer can still be viewed on the CSIRO website.

Two sharks tagged in March in the same year were found to go their separate ways, one swam to the Great Barrier Reef for the winter before returning to the Bass Strait while the other headed west and ended up between Albany and Esperance.

Mr Bradford said it would be exciting to watch Columba's movements over the next few weeks to see where she went and if she stopped to give clues as to why this species of shark moved to the northern WA waters at this time of year.

"This track is also consolidating our picture that white shark movements are not random but follow patterns with visits common to particular places at particular times of year - with some sharks appearing to follow common routes when they travel."

Eventually the researchers will use the information found through shark tracking to minimise interactions between sharks and people.

Mr Bradford said there was currently no tracking of sharks on Eyre Peninsula.


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