The Food Safety Authority of Ireland (FSAI) has expressed concern about an increase in algal blooms which has caused the temporary closure of over 30 bays and sea areas where shellfish are being cultivated.
The unusually high number of harbours, estuaries and bays subjected to harvesting bans is being linked to rises in water temperature, and may be due to the additional influence of increased nutrients, notably nitrates and phosphates which usually arise from sewage and/or agricultural wastes. Where these conditions occur, algae are likely to proliferate, causing a "bloom".
The Irish Shellfish Association (ISA) has called for more research into the causes, and a more frequent monitoring programme to allow bays to reopen when safe to do so. Otherwise, farmers in the £40 million shellfish industry stand to lose heavily this year, it warns.
Some 130 bays, estuaries and sea areas under shellfish cultivation are tested by the Marine Institute weekly for toxins, linked to a group of phytoplankton known as dinoflagellates. The particular bloom associated with current closures, dinophysis, is naturally occurring. Although it is not harmful to the shellfish, the toxin can cause diarrhetic shellfish poisoning in humans who may have consumed the seafood.
Most of the areas are under mussel cultivation, and recommended closure is usually taken in conjunction with the local health board. Toxicity can occur at any time of year, and periods of closure can vary considerably. However, one area in Bruckless, Co Donegal, has been closed for most of the year, according to the FSAI's director of operations, Mr Alan Reilly.
Bays, estuaries and sea areas currently closed to shellfish-harvesting under the Marine Institute's shellfish biotoxin testing programme include: CurraunAchill island, Co Mayo; Adrigole, Co Cork; Ardgroom, Co Cork; Arranmore and several sites near, Co Donegal; parts of Bantry Bay, Co Cork; Bruckless, Co Donegal; Cahirciveen, Co Kerry; Castle townbere, Co Cork; Cromane, Co Kerry; Dingle harbour, Co Kerry; Gearhies, Co Cork; Glengarriff, Co Cork; Gweedore, Co Donegal; Killary, Co Mayo; Kilmac allogue, Co Kerry; Mountcharles, Co Donegal; Mulroy Bay, Co Donegal; Roaringwater Bay, Co Cork; Sneem, Co Kerry; Whiddy, Co Cork; Ventry, Co Kerry.
The shellfish and finfish industry has grown substantially since the late 1970s, and so the impact of blooms is far more serious, although the current type are not those responsible for Red Tide, which has severe health implications for humans. Some scientific research suggests global warming may be increasing the frequency of the blooms.
Mr Richie Flynn of the ISA says his members would like to see twice-weekly monitoring for biotoxins, to allow areas to be opened up immediately when cleared to do so.
"The big worry is for those shellfish-farmers who are hit by September storms before they have a chance to harvest, when it may be perfectly safe to do so," he said yesterday. The decision to close was based on a precautionary approach, he said, with some areas safe for harvesting again within a week.
The FSAI advises consumers to buy shellfish from reputable dealers, and to make sure that any cooked mussels have open shells before consuming. "Mussels that stil have closed shells should be discarded," it said. The FSAI helpline for inquiries on food safety issues is 1890-336677.
