An algal bloom in Dingle Bay in Co Kerry is leading to an ecological disaster in marine terms, according to a sea fisheries officer and marine expert.
The Marine Institute, which carried out a survey of the area, also said the naturally occurring bloom was one of the most severe ever to hit the area, but said it was confined in the bay. Fish-kills were being reported continuously all around the bay from Kells, Rossbeigh and Cromane.
Satellite images of the "red tide" of the microscopic plankton species called Karenia mikimotoi bloom, which began in the northwest in mid-June, show it extending up to 100km from the Irish coast. Affected areas include the Donegal coast, where the absence of prawns has been reported, and the Mayo and Galway coasts.
The bloom struck the Dingle Bay area over a week ago. High cell counts were reported in Ventry, Dingle harbour, Glenbeigh and Cromane. Pockets farther south were also hit. It has now wiped out stocks of turbot, plaice, young cod, conger eel and brill.
There are reports that significant numbers of farmed shellfish, particularly cockles and some mussels destined for the French market, have been destroyed, with the Glenbeigh area one of the worst affected.
"We are now talking about huge marine dead zones," said Kevin Flannery, sea fisheries officer with the Department of the Marine.
Stocks of young turbot and plaice and the hardier mullet have been hard hit in the estuaries, particularly on the south of the bay.
Along with flatfish, finfish and shellfish, lug worms, crabs and starfish are dying from the low oxygen and mildly toxic bloom.
However, Fungi, the Dingle dolphin, and other larger marine animals are safe. Lobster is also unaffected, fishermen reported yesterday, but the flatfish that gather around the lobster pots are dying in the pots.
Department of the Marine officials urged the public not to pick or handle wild shellfish in the area. None of the affected farmed shellfish was allowed into the market, and the bloom, which appears reddish-brown, was not harmful to humans, they said.
According to the Marine Institute, Karenia mikimotoi was first identified on the east coast of the US in 1957 and was first recorded in Europe in 1966 when it bloomed in Norwegian coastal waters.
It was first recorded in Irish coastal waters in 1976 when it bloomed extensively on the southeast coast. Subsequent blooms were recorded each year between 1978 and 1982 and again each year between 1990 and 1995.