ABSTRACT
The European flat oyster Ostrea edulis L., family Ostreidae, has a shape typical of a reclining species. The valves are subcircular to circular; the left valve is deeply concave and the flat right valve acts as a lid. The European oyster is a protandric hermaphrodite, changing sexes generally twice during a single season. Oysters can also be ambisexual to some extent, with male and female gametes present in adjacent follicles. The European oyster fishery in Maine and eastern Canada originated from intentional introductions in the 1940s and 1950s. Later, in the 1970s, additional European oyster populations were “introduced” as part of aquaculture raft culture operations and may have functioned as broodstock populations It is important to speculate on the origin and future of the new natural European oyster fishery in Maine. The danger of low temperatures necessitated a dual-site culture, in which oysters were moved to more marine sites for the winter, where higher water temperatures prevailed.
