Wind changes may explain why gemfish disappeared

AAP General News (Australia)
04-10-2000
Wind changes may explain why gemfish disappeared

A climate conference in Hobart has heard the mysterious disappearance of gemfish from
off the New South Wales coast in the past 10 years may have been caused by changes in
wind patterns.

Up to 5,000 tonnes of gemfish a year, worth about $12 million, were caught in the area
in the 1970s and 80s -- but the fishery suddenly collapsed in the early 1990s.

However, CSIRO fish ecologist RON THRESHER says while over-fishing played a part, a
weather pattern that follows a 10-year cycle is a key reason for the disappearance of
the popular-eating species.

Dr THRESHER has told the Tasmanian conference that surface-dwelling gemfish larvae
rely on strong westerlies to stir up nutrients so they can reproduce successfully.

The winds in turn rely on the position of bands of high and low pressure that divide
the easterlies of the north from the westerlies of the south.

As the band moves south, the westerlies die and fish like gemfish, abalone and Bass
Strait scallops collapse.

Dr THRESHER says other species, such as the stripey trumpeter, and flathead, are also affected.

The ecologist says there should be some gemfish recovery when the cycle changes -- but
he doubts it'll ever become a commercial stock again.

AAP RTV dw/sub/jn

KEYWORD: FISH (HOBART)

2000 AAP Information Services Pty Limited (AAP) or its Licensors.