In excess of 1,000 fish were killed in the Ballygowan River near Claremorris in Co. Mayo after it was polluted by an effluent that is suspected to be of agricultural origin, according to Inland Fisheries Ireland (IFI).

An investigation into the “significant” fish kill is underway and water samples have been taken for analysis. Officers from IFI were first made aware of the incident Friday, June 8.

The river in question, which flows into Lough Mask, is one of the prime spawning tributaries of the Robe River.

In a statement, the IFI said: “It is believed that the fish kill was the result of effluent of agricultural origin, although the precise source has not as yet been identified. Local reports noted fish, primarily wild brown trout, in an agitated state in the river on Tuesday evening, June 5.

“The stream where the mortalities occurred currently shows no sign of enrichment, and it is therefore probable that some polluting matter of a transient nature passed through the river and has since dissipated downstream.”

It is estimated over 1,000 wild brown trout from zero to four years of age have been removed dead from the river – while other fish mortalities included stone loach and crayfish.

Due to the extent of the damage caused, it is feared that it will take some years for the affected stretch to make a full recovery.

‘Water levels are at an all-time low’

Currently, water levels are at an all-time low and water temperatures are getting very high for trout and salmon, according to head of operations at IFI Greg Forde.

Continuing, he said: “These factors combined can mean that a small amount of polluting matter can have devastating results.

IFI is calling on all farmers and silage contractors – in particular – to be extremely careful in the current conditions to ensure that no effluent is released near drains, streams and rivers, and that silage clamps are properly bunded.

“Extreme care should be taken when spreading slurry to avoid all water courses in order to protect our valuable natural rivers and streams.”

The public can contact the IFI to report incidents or suspicions of illegal fishing to its confidential hotline number by calling: 1890-347424.