Marennes Oléron oysters enjoy the same attention as Bouchot mussels and have become part of the heritage of Charente-Maritime.
Unlike sea oysters, Marennes Oléron oysters spend their whole lives growing on oyster beds ('claires') or are moved there to complete their maturing process.
It is this specific way of rearing the oyster that allows it to gradually take on all of its distinctive characteristics over the course of the maturing process. Marennes Oléron oysters are not as bitter or salty as their counterparts from the sea, and have a better capacity to retain water (because they are not always covered by the sea), which means they keep better.
However, this way of breeding oysters does not only have an effect on their flavour or how long they stay fresh, it also boosts the growth of the oyster's flesh and shell, and actually improves the quality of the shell (the outer surface remains untouched by parasites and the inner surface is covered with mother-of-pearl). Other consequences of this breeding technique are the natural purification of the oyster and the greening of its gills.
Once in the oyster bed, the degree to which the oyster is transformed can be controlled, enabling breeders to obtain various types of this produce: 'Fine de Claire' oysters (rich in water, with exquisite flesh and a balanced flavour), 'Fine de Claire verte Label Rouge' oysters (displaying the natural greening that takes place in the oyster bed), 'Spéciale de Claire' oysters (both round and voluminous), and 'Spéciale Pousse en Claire Label Rouge' oysters (with plump, firm, crunchy, ivory-coloured flesh, and a pronounced flavour).