Toxic chemical spill likely cause of one of largest fish kills in history of the State

An estimated 50,000 fish species have been wiped out along the River Blackwater and some of its tributaries in North Cork

The fish kill, originally confined to the rivers between Banteer and Killavullen bridge, is spreading fast. Picture: Facebook/Conor Arnold

A toxic chemical spill now seems the most likely cause of what is claimed to be one of the largest fish kills in the history of the State.

The recent kill, estimated by local angling clubs to have so far claimed the lives of more than 50,000 fish species along the River Blackwater and some of its tributaries in North Cork, was initially believed to be due to the rapid spread of a bacterial infection.

However, Inland Fisheries Ireland (IFI) and the Marine Institute are now examining if the deaths of the huge number of fish in the region could also be due to a viral infection, but did say in a statement that it could well be as a result of “an environmental irritant.”

When asked by the Irish Examiner to clarify what that meant, IFI admitted that it could be a toxic chemical spill.

This matches the findings of an independent senior scientist brought in to evaluate the kills by trout and salmon clubs in the impacted areas.

Sue Mitchell, a senior scientist who is EU-accredited for her work, reported to the clubs that after carrying out numerous tests on the local waters, she had come to the conclusion that the likely cause of the major kills was down to “run-off” from an industrial chemical spill, or agricultural spill.

Her findings were presented at a meeting held in Mallow attended by local angling groups, which was attended by minister of state for fisheries and the marine, Timmy Dooley; IFI acting CEO Suzanne Campion; and senior officials from IFI and the Environmental Protection Agency (EPA).

Conor Arnold, who owns a fishery stretch on the Blackwater in Castletownroche, had sought the report from Ms Mitchell, on behalf of the angling clubs, which he delivered at the meeting.

Mr Arnold said the fish kill, originally confined to the rivers between Banteer and Killavullen bridge, is spreading fast.

“Fish are now not feeding in the Blackwater tributaries as well, such as the Ross stream in Killavullen, the Clyda river in Drommahane and the Awbeg flowing through Castletownroche [and Doneraile] and a number of small streams adjoining them,” he said.

“They are not feeding because they can’t see, and therefore they are likely to die.”

The decimation of aquatic life along the Blackwater Valley includes game fish such as salmon and trout, and coarse fish such as roach, dace, eels, and the small stickleback.

Very endangered species such as the EU-protected freshwater pearl mussel and lampreys are also said to have been wiped out along a 40km stretch of the Blackwater and its feeder rivers and streams.

IFI said in a later statement that lesions on the fish indicated an “environmental irritant” which caused problems to ‘the gills, skin and eyes’ of the dead fish.

The fishery protection authority added that to date, the EPA has not raised concerns about water quality along the main river and its feeder tributaries, but said more water quality results will be available in due course.