ABSTRACT
Pacific oysters Crassostrea gigas were introduced to the coastal waters of France by mass importations beginning in the late 1960s, after the native oysters had declined in abundance dramatically, due mostly to effects of epizootic diseases. Countless millions of seed oysters were airlifted from Japan during the period 1968 to 1974, with hope of reestablishing the industry in such traditional French oyster growing areas as Arcachon, Oleron, Marennes, and La Trinité. Initial results of the mass transplantation were very encouraging. The introduced species survived, grew, and even reproduced in some protected coastal waters. By the mid-1970s though, indications of a severe problem with these immigrant oysters were appearing in some of the bays. They were exhibiting poor growth and grossly malformed shells. Shell abnormalities that made the oysters unsalable reached an intolerable level of 90% in the Bay of Arcachon in 1980 to 1982 — just as an example.
