Fish Kills in Ireland in 1994 and 1995

Abstract

In 1994, the downward trend in numbers of fish kills continued, the total for the year being 32. However, in 1995 a long spell of dry weather greatly reduced the flow in rivers in all parts of Ireland and the number of fish kills rose to 84, the highest since 1989. In 1994, farmyard effluents, silage and slurry together accounted for one third of the fish kills. Industrial effluents and enrichment both caused 19% of the total. Storm water runoff and cement spillage in building operations were the other identified causes. In 1995, enrichment was the most frequent problem, followed by agriculture. Inadequately treated sewage was implicated in five cases and waterworks effluent in two. In 17 cases the mortalities were associated with reduced water flows or high temperatures or a combination of the two. The dry summer in a number of cases revealed unsatisfactory levels of pollution which are usually masked by higher water flows such as occurred in 1994. The increase in farm-based problems suggested that some of the improved facilities for storage and treatment of farm waste which were made in the late 1980s may now be due for maintenance. Enrichment of lake systems, particularly those of the Erne and Shannon, has now established itself as the most serious threat to the condition of natural waters. Fish kills are an early warning of a situation which may develop and have far-reaching effects on economic interests far removed from the fishery itself.