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Port Lincoln TimesAustralian News    2/04/2005 20:58:27

Stan Gorton

The Australian tuna industry is questioning the models and systems used to calculate fish numbers after southern bluefin tuna continues to be listed as being overfished.

The Bureau of Rural Sciences annual report into the sustainability of Commonwealth fisheries released this month identified tuna as being overfished.

While conservation groups such as the Humane Society International continue to call for southern bluefin to be protected as an endangered species, the Australian tuna industry said it was disappointed with the report's conclusion.

Even though the report was based on the Commission for the Conservation of Southern Bluefin Tuna (CCSBT) latest figures presented at a conference in Korea last year, tuna industry spokesman Brian Jeffriess said the figures could be wrong.

The CCSBT 2004 report on stock status results suggest there is approximately a 72 per cent chance that current catches will lead to a lower spawning stock biomass in 2020, but he said the problem was that the models were based on flawed data.

Declining tuna prices and increasing fuel costs meant Japanese long-liners were discarded all but the best fish and not recording their total catch meaning the data did show all the tuna that was being encountered at sea, according to Mr Jeffriess.

"Logic suggests there are more fish being encountered by these long-liners than is being reported," he said.

Acoustic tagging and other research off Western Australia also pointed to stock declines, but again Mr Jeffriess took issue with the methodology used.

The Humane Society meanwhile viewed the Bureau of Rural Sciences and CCSBT findings as back up to its argument that a more conservative approach needed to be taken with the species.

"For 15 years the Australian fishery has not reduced its pressure on southern bluefin tuna despite the seriously depleted state of the stock," HSI wildlife and habitat program manager Nicola Benyon said.

Provisions exist within Australia's SBT Management Plan to allocate a quota below that agreed at the international commission and it was high time the Government exercised this option, she said.

Tagging data from the Great Australian Bight shows record numbers of fish to tag.

Good weather meant 9085 tuna were tagged off the West Coast in December and January, while 7800 fish were tagged off WA this season.

But CSIRO fisheries biologist Dr Clive Stanley said it was somewhat concerning that taggers could only located fish at Nuyts and Yatala reefs, when in the past fish had been present at several other inshore lumps.

While Mr Jeffriess said scientists should take into account the experiences and opinions of long-term fishers, Dr Stanley said tagging data had to be analysed over the long-term and it was too soon to pick up trends for the Bight.

Another local fishery classed as overfished was the school shark.