THE latest fishkill on the River Lee is the third such serious incident in the South Western Regional Fisheries Board area in the past few months. About 80,000 salmon and trout have been killed by pollution already this year.
Last Thursday, the ESB salmon hatchery at Carrigadrohid, which is used to restock the Lee, was left with only 15,000 salmon parr, out of a stock of 90,000, after a sudden depletion in water quality.
Experts at the Aquaculture Development Centre in University College, Cork, are now examining some of the dead fish to determine whether lack of oxygen in the water or an algal toxin was responsible for the kill. It is thought that a toxin is the more likely cause.
Last April, more than 1,000 salmon, brown trout and sea trout were killed on the Milltown River near Dingle, Co Kerry.
In June, some 3,000 salmon and trout were killed on the River Martin, near Blatney, Co Cork, when a farmer left a slurry hose running in a marshy area above the river. The slurry leached into the Martin and then affected the adjoining River Shournagh, which in turn flows into the Lee.
The slick of slurry drifted into the Lee below the main water treatment plant for Cork, threatening the city's water supply. However, the ESB released thousands of gallons of water from its dam at Inniscarra into the Lee valley, diluting the slurry and averting closure of the plant. The farmer, who allegedly has been identified, faces prosecution by the fisheries board.
The hatchery kill means the restocking programme on the Lee has been seriously set back. The parr were hatched last December and were scheduled to be released to the sea in March/April of next year. They were due to return to the Lee in 1998/1999 as mature fish.
It is unlikely that the ESB will replenish the stocks with fish from other hatcheries as this would interfere with the genetic profile of fish native to the Lee.
The policy on the rivers Martin and Shournagh is also not to restock for similar reasons, and it could take years before the native fish population has been restored in these systems.
The ESB is obliged under legislation to carry out a restocking programme on the River Shannon, but in the case of the rivers Lee, Liffey, Erne, and the Clady Crolly system in Donegal, it does so voluntarily.
The Carrigadrohid hatchery is one of the largest and most successful in the State and while there have been pollution incidents in the past the latest one is regarded as the most serious in its history. In terms of monetary value, the fish would not have been worth more than £6,000, according to an ESB spokesman, but when looked at from the point of view of conservation the loss is much more damaging and long term.
Under the 1987 Water Pollution (Amendment) legislation, the maximum fine for pollution on summary conviction was increased from £250 to £1,000 and to £500 from £100 for every day on which the contravention continues.
The maximum penalty on conviction on indictment was increased from £5,000 to £25,000 and from £500 to £5,000 for each day of the contravention. This fine, applicable in the higher courts, also provides for an alternative prison sentence of five years.