There were 111 fish kills in north west rivers and lakes from 1969-2022, Inland Fisheries Ireland has revealed.
Figures published in a major report show there were 61 in Donegal, 28 took place in Sligo and in Leitrim the figure was 22.
Brown trout and Atlantic salmon were the species worst affected, followed by roach and European eel.
The report shows that counties Cork and Cavan had the worst record, accounting for the highest proportion of kills.
While counties Roscommon and Westmeath had the lowest proportion.
The detailed study is the first comprehensive overview of related trends, locations, causes, and population recoveries over the 53-year period.
