Fish Kill Cause Still Unknown

20 March, 2003

The cause of two recent fish kills at Fraser Island is still not identified despite extensive scientific tests.

About 400,000 small threadfin leatherjackets died in two recent fish kills at Fraser Island, the first resulting in fish washing up along the entire east coast of the island and the second, mainly centring around the north-east beaches.

Department of Primary Industries Queensland Fisheries Service (QFS) principal scientist John Beumer said laboratory results did not support either biotoxins or a virus as the cause.

“Initially we thought it could be biotoxins in the inshore environment. Toxic algae produce biotoxins which may lead to fish being poisoned,” he said.

“However, the tests have ruled out both of these possibilities and at this stage it seems unlikely we will find out the cause.”

Dr Beumer said human activity had also been ruled out as only a single species of fish was affected.

“Fish kills caused by poor water quality, pesticide run off and similar activities are generally characterised by a wide range of species being affected,” he said.

Dr Beumer said leatherjackets were also involved in another major fish kill on Fraser Island in 1998.

He said there was also no specific cause identified as being responsible for that incident.

Dr Beumer said a species related to the leatherjacket from the inshore waters of Hawaii was also known to have regular large-scale fish kills.

“The cause behind these fish kills has been identified as a lack of available food following large numbers of fish migrating inshore over a short period of time,” he said.

“In open water situations such as off the ocean beach at Fraser Island, the cause of fish kills often remains a mystery but we are still waiting some final test results to see if they shed any further light on the matter.”

Department of Primary Industries Media Unit
GPO Box 46 Brisbane Qld 4001 Ph 07 3239 6380
DPI Call Centre 13 25 23 (weekdays 8 am to 6 pm)

Further information: John Beumer (07) 3224 2238
Communications Officer: Liz Smith (07) 3224 7757

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