Inland Fisheries Ireland (IFI) says it is investigating a serious fish kill incident at Barnagrow Lake near Shercock in Co Cavan, within the Annalee River and Upper Erne catchment area.

Environmental and fisheries officers from the North-Western River Basin District were alerted to the incident by a call from a member of the public this past Tuesday (27 July).

And the State agency responsible for the protection and conservation of freshwater fish and habitats estimates that there could be in excess of 5,000 fish mortalities, including species such as bream, roach, perch and pike.

Fish samples have been taken from the lake and removed for further analysis. Initial investigations indicate that a severe algal bloom, combined with high water temperatures and low oxygen levels recorded in Barnagrow Lake, are the likely causes of the incident.

Dr Milton Matthews, director of the North-Western River Basin District with IFI, said: “Unfortunately, this is a very significant fish kill affecting several year classes of coarse fish and is the largest reported fish kill nationally to date in 2021.”

He added: “During the recent heatwave, very high water temperatures were noted at several angling locations, with temperatures of over 26 degrees [Celsius] for example recorded in Lough Sheelin, Co Cavan.

“In the days preceding the fish kill at Barnagrow Lake, a severe algal bloom was noted by Inland Fisheries Ireland staff, which together with very high water temperatures recorded locally, which were 22 degrees [Celsius], likely resulted in this serious fish kill event due to reduced oxygen levels in the water.”