AN investigation is taking place into the deaths of hundreds of fish in Lough Derg on the Shannon.
Dead bream - the only fish species affected - were first noticed on the lake between Portumna and Killaloe during the Easter holiday weekend.
The Chief Officer of the Shannon Regional Fisheries Board, Mr Eamon Cusack, said the board is waiting for the results of an investigation.
First indications are that the problem is disease related as no other species is affected, he suggested. He said fewer fish had died in recent days. The board was continuing to monitor the situation with UCG, which was carrying out tests on the lake on behalf of the ESB.
Mr Cusack said the lake had no algae at present and was in reasonably good condition.
Local people are concerned at the implications of the fish deaths for tourism. Dead bream have been seen on the lake in isolated incidents over the past two years.
A water quality study on Lough Derg costing £80,000 has been carried out by the Environmental Protection Agency and Teagasc.
It concluded there has been a substantial deterioration in water quality over the past eight to 10 years. However, in comparison to other European countries, the standard is high.
Following that study, the Department of the Environment has put forward a series of schemes to clean the lough.
The schemes, which are costing £30 million, were this year approved for grant aid by the EU.
Lough Derg is worth over £10 million per year in tourism revenue, and it is estimated that with new investment this figure will rise to £20 million by 1999.