15 July 2005

Tagged great white shark swims 7000 km into uncharted waters and back

A GREAT white shark tagged in the Neptune Islands has swum 7000 kilometres to Rockhampton in Queensland and back to the Neptune Islands in less than a year.

The shark was one of two tagged in March as a prelude to the tagging program in November when four sharks were tagged which are now providing scientists with information on regular trips between the nearby islands, the Head of the Bight and central Spencer Gulf.

The satellite tags placed on the back of these sharks by Australia's science agency CSIRO may have shattered the myth that great white sharks habitat one particular beach terrorising the locals.

CSIRO scientist Barry Bruce said the tag attached to the shark known as Bruce gave its last transmission to orbiting satellites back in November when the shark was in Bass Strait.

"We knew he spent the winter off Rockhampton, then a few months off New South Wales before heading down to Bass Strait in November," Mr Bruce said.

"We were wondering whether he would head back to South Australia."

While shark Bruce's electronic tag had expired, a chance spotting off the Neptune by local charter boat operator Rolf Czybayski who assists with the tagging program has helped complete the puzzle.

Shark Bruce was seen from the deck of the Calypso Star on January 9 and 10 revealing his 7000-kilometre round trip to the tropics.

Barry Bruce said it was not clear what food source attracted the shark to Queensland but that it was more evidence that even large sharks between three to four metres in length had very diverse diets.

"If anything, they are more reliant on things other than seals and this disproves the common thought held by all observers and scientific literature," he said.

The other shark tagged at the same time as Bruce known as Lulu has also not been heard since October but spent most of her time in Western Australia between Esperance and Albany.

This opportunism and willingness to travel vast distances in short periods is backed up by the four male sharks also between three and four metres tagged in November.

The sharks are being tracked now with weekly paths posted on the CSIRO website with a one-week delay and there have been some very interesting developments in recent weeks.

Sam C has now come back from the Head of the Bight following the exact track of one of the other tagged sharks known as Michael who also swam back and who in recent weeks was still in the area.

"This is a classic highway they are going up and down," Mr Bruce said.

Then in another case of follow the leader, Sam C swam off in a northerly direction to central Spencer Gulf in an area roughly off Franklin Harbour, the exact same location the shark known as Rolf headed and was last heard from.

Mr Bruce said he was not that concerned to have not heard from either Rolf or the other tagged shark known as Bomber over recent weeks, as the tags sometimes temporarily stopped transmitting and depended on the sharks surfacing for some time.

Source: portlincoln.yourguide.com.au


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