Fish Kills in Ireland in 1990

Abstract

The total of 52 fish kills in 1990 was a marked improvement over the previous year when 111 were reported. Although this result was no better than that for 1988, it represented a considerable achievement because 1988 experienced a wet summer with high water flows while 1990 was exceptionally dry. Because of the poor dilution of pollutants, low river flows are usually associated with an increase in the number of fish kills. All three traditional causes of fish kills, agriculture, industry and sewage showed a downward trend. These have all been subjected to a campaign of information and enforcement of the regulations. This has brought about an increased awareness of the hazards and major improvements have been made in reducing the risks of accidental spillages. In spite of these efforts, the problem remains very serious. Although so much better than the peak figures of more than 100 fish kills in a single year, the level of 50 is unacceptably high. The analysis of the year's results shows that agricultural sources continue to cause extremely serious damage. The problem lies partly in the fact that a single accidental discharge into a salmonid nursery river can kill many thousands of fish for as much as 20 kilometres downstream. If the downward trend of problems from agriculture and industry can be maintained, the greatest threat in water pollution is likely to be that of enrichment, above all the release of excessive phosphate into the environment. Two sources, fertilizer and domestic sewage, are implicated. The sewage element can be controlled by upgrading treatment plants wherever necessary. The reduction of phosphate runoff requires continued attention to the information campaign for farmers to explain the: need for extreme care in fertilizer application. Remedial action in this case increases farm profits since all the fertilizer which pollutes the rivers is lost to the land.