The Owenmore River in Sligo and its tributaries have been closed for all fishing due to the ongoing outbreak of disease in the salmon population.
It’s estimated that well over 900 salmon are now confirmed dead in the nearby Ballisodare River.
The State has closed the system until further notice.
A multi agency investigation into the cause of the deaths is ongoing.
Inland Fisheries Ireland has reiterated that it's conducting a full environmental analysis within the catchment in an effort to investigate whether water quality issues may be a factor.