Inland Fisheries Ireland says it’s pursuing a definite line of inquiry into the cause of a major fish kill in Kiltimagh, Co Mayo last week.
The environmental agency is still analysing samples from the Glore River near Kiltimagh on Friday.
500 juvenile salmon and trout were found dead along a 2km stretch of the tributary of the River Moy.
Greg Forde, head of operations at IFI is very concerned for the safety of one of the most important salmon rivers in Ireland.
