Farming was the most significant reported cause of fish kills in Ireland from 1969 to 2022, accounting for 23% of overall causes, a report has found.

Inland Fisheries Ireland (IFI) published a new report on 2,107 fish kills which occurred in Irish rivers and lakes over the 53-year period.

The report revealed that the most common known cause of fish deaths was agriculture, followed by eutrophication, industrial, municipal, mining, construction and other activities.

Separately, IFI records show that almost 19,000 fish died in 30 recorded fish kill occurrences between January 2023 and July 2024.

Fish mortalities included Atlantic salmon, trout, eel and lamprey of all ages.

Municipal sources

The report also found that fish kills occurred in every county since 1969.

The highest percentage of fish kills attributed to municipal sources - a cause which has more than doubled since 2007 - was recorded in Co Laois, followed by Cork, Cavan, Dublin and Tipperary.

Counties Cork and Cavan had the highest proportion of fish kills, while Co Roscommon and Co Westmeath had the lowest in the period from 1969 to 2022.

Rivers were the most impacted waterbody type (81%), followed by lakes (12%) and artificial waterbodies, such as ponds and canals (5%).

Lead author on the new report and eastern region director at IFI Dr Ronan Matson said: “Fish kills caused by pollution are heartbreaking for local communities. Many of these lethal events are needless, avoidable and criminal.

"The ripple effect of ecological damage on biodiversity is long-lasting - at a time of rapid environmental change. Best practice must always be adhered to in all works in or near watercourses."

IFI staff deploy an emergency response to any fish kill incident. It is crucial that any signs of concern are reported immediately to its 24/7 number, 0818 34 74 24.

The Department of the Environment, Climate and Communications is currently carrying out a review of inland fisheries legislation.

Existing sanctions are being examined and it would include a potential update of penalties in respect of fishery, environmental and other offences.