Pacific Oyster invasion threatens Irish ecology

Invasive Pacific oysters on the Irish coast are now thriving outside of their original farmed colonies, a study has shown.

Dr Stefano Mariani of the University of Salford led a year-long project to genetically compare members of the wild and farmed colonies.

Pacific oysters, native to Japan and Korea, were introduced to Europe in 1966 to replenish overfished native stocks. But Dr Mariani concluded that the ‘feral’ oysters were genetically different enough to be considered separate colonies.

The potential impact of a feral species spreading across the Irish coast unchecked is enormous. “Now the Pacific oyster is with us, the far-reaching consequences of its establishment are still debatable, but just controlling aquaculture is no longer an effective means to reduce its further spread”, said Dr Mariani.

Management at Lough Foyle, where the farms are situated, has focused in the past on containing oysters. The researching student, Judith Kochmann, now believes more extensive controlling measures are required.

The introduction of a feral species has consequences both for local conservation groups and industry in the area, according to Dr Mariani. But he believes that controlling feral colonies is no longer enough, attitudes must change as well. “We may enjoy our oysters with Guinness or champagne, but we should now think more deeply about our insatiable need for more and more easy-to-access commodities.”