Bonamia ostreae in the Native Oyster Ostrea edulis

Ireland has a long history of producing and harvesting native flat oysters, Ostrea edulis. At the start of the nineteenth century, almost every bay and harbour, around the coast had abundant beds of native oysters. Intensive dredging to meet the demands of the markets in Dublin and England depleted the stocks, so that in 1845 the government passed legislation to permit the formation of private oyster beds to improve the ailing stocks. According to the book on “Shellfish & Shellfisheries of Ireland” (Wilkins, 2004) Irish stocks began to collapse between 1850 and 1860. By the second half of the twentieth century, only the beds of Tralee Bay, Galway Bay and Clew Bay were still yielding a good return for local fishermen. \nThe arrival of the oyster parasite Bonamia ostreae in the mid 1980s was an additional blow to the Irish native oyster stocks. This report sets out to document the spread and the impact of the Bonamia ostreae parasite in Irish bays since the 1980s.