Largest fish kill of the year linked to very high temperatures

A severe algal bloom and very high water temperatures are likely to have caused the fish kill in Co Cavan. 

The largest fish kill of the year has been linked to “very high” water temperatures recorded during the recent heatwave.

Inland Fisheries Ireland (IFI) estimates in excess of 5,000 fish may have died in the fish kill incident at Barnagrow Lake in Co Cavan.

A member of the public alerted environmental and fisheries officers to the incident on Tuesday. Species such as bream, roach, perch and pike are among those killed.

“Unfortunately, this is a very significant fish kill affecting several year classes of coarse fish,” Milton Matthews, director of the north-western river basin district with IFI, said.

During the recent heatwave, “very high water temperatures” were noted at several angling locations, he said, and in the days preceding the fish kill at Barnagrow Lake, a severe algal bloom was noted by IFI staff.

[This] together with very high water temperatures recorded locally, which were 22C, likely resulted in this serious fish kill event due to reduced oxygen levels in the water. 

Fish samples have been taken from the lake and removed for further analysis.

Members of the public are encouraged to report fish kills or sightings of fish under distress by calling Inland Fisheries Ireland’s confidential hotline number on 1890 347424, which is open 24 hours a day.