Awareness of biodiversity
Status of biodiversity
Threats to biodiversity
Measures that safeguard biodiversity
Measures that mainstream biodiversity
Benefits derived from biodiversity and ecosystem services
Impacts on biodiversity outside of Ireland
Knowledge of Irish biodiversity
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Fish mortalities in rivers and lakes are reported as ‘kills’ if there is a strong suspicion that the cause of the mass mortality is pollution or otherwise unnatural. Mortalities due to natural causes, e.g. salmon and lamprey die naturally after spawning, are not considered kills. The primary cause of fish kills in Ireland is the deoxygenation of water brought about by anthropogenic inputs of organic matter resulting in excessive plant growth. Silt is a secondary driver of fish kills by clogging gills or smothering eggs and/or fry in spawning areas.
In the past 40 years, the number of reported fish kills has declined from a peak of 235 in 1986-1988 to a low of 72 cases in 2007-2009. Up until 2007-2009, agricultural activities was the most frequently reported cause of fish kills representing an average of 38.3 ± 5.3 % (± 95% CI) of cases per reporting period, compared to 18.2 ± 4.0 % for industry and 13.2 ± 4.6 % for other causes. However, in the latest reporting period, other causes including oil spillages, high water temperatures, or extended periods of low water flow, were the leading driver of fish kills representing 55.7% of reported cases.
To report a pollution event or a suspected fish kill, please contact Inland Fisheries Ireland here:
Further information on fish kills in Ireland can be found here:
Whether by accident or otherwise, fish kills can represent a breakdown in pollution control strategies in aquatic environments. This indicator focusses on the number of reported fish kills investigated by Inland Fisheries Ireland.