The South-Western Regional Fisheries Board yesterday reported the first fish kill in the region this summer.
Up to 1,000 young fish, including young salmon parr, trout, eel and other species, were found dead on a tributary of the River Bride, upstream from Béal na Bláth in Co Cork. The kill took place on Monday.
A two-mile stretch of the river has been affected. The Bride is a tributary of the River Lee.
The chief executive of the fisheries board, Mr Aidan Barry, said it was investigating the incident but was satisfied the pollutant was silage effluent.
He appealed to farmers to be extra vigilant in light of the recent wet weather and to inspect silage and slurry holding facilities. The period between June to the end of August is the worst for fish kills.
"As well as asking for extra vigilance because of the higher water content in silage this year, I would also appeal to farmers to inspect silage tanks," Mr Barry said.
Over the past five years, a certain style of silage tank in use since the 1970s in the region was found to give problems, he said. The tanks concerned had wooden or rubber bungs at the bottom, designed for ease of cleaning and emptying purposes. However, often when these tanks filled, the bung was forced out and the silage spilled.
"These tanks should not be in use now," Mr Barry said, urging farmers to use concrete tanks without such holes.
Of 216 reports of an environmental nature investigated by the region's fisheries board during 2001, almost one-quarter concerned slurry and silage spills.
A survey of 417 farms in six river catchments during the year resulted in 204 warning letters, issued mainly because of inadequate slurry and silage effluent holders and over-flowing tanks which had the potential to pollute.
Development and roadworks carried out by local authorities and land-owners are also potential sources of major pollution.
During 2001, three fish kills were recorded in the region between mid-July and September.
One was caused by farm effluent, one by river drainage and the third related to problems specific to the lake concerned.