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10,000 Southern Bluefin Tuna Taggedff

14 April 2004 Australia

Researchers tagging southern bluefin tuna in the Great Australian Bight are not having any trouble locating fish to tag although weather conditions have affected fishing.

Commonwealth Scientific and Industrial Research Organization (CSIRO) scientists working for the Commission for Conservation of Southern Bluefin Tuna (CCSBT) so far this year have already tagged just over 5000 tuna off Fowlers Bay and a further 5000 tuna off Western Australia.

And tagging was due to recommence in South Australia on April 5.

CCSBT executive secretary Brian Macdonald said it was overly simplistic to say the numbers being encountered meant the species was now plentiful.

Much more scientific analysis of the data was needed, with one positive being that of the 20,000 tuna tagged so far by the commission in recent years, only about 350 had been caught in purse seine nets.

The fact that not many of the tagged fish are being recovered leads researchers to speculate the overall stocks must be relatively healthy as opposed to the worst-case scenario where all the tagged fish were showing up in the nets.

But again more research into the data was required before a conclusion could be reached and the purse seine fishing tag returns did not prove anything scientifically.

”We can't really draw any conclusion from purse seining because the scientists say it concentrates the fishing effort and so is not representative,” Mr. Macdonald said.

The goal every year is to tag about 9000 tuna off South Australia and 6000 tuna off Western Australia, with researchers returning to the Great Australian Bight this month to complete the rest of the tagging work.

Fishing company AFE are providing the vessel and crew to take the researchers out to the Bight and to pole the tuna using traditional methods.