Here's a slideshow made up of a lot more photos that I took on the Île d'Oléron in May 2008. The oyster farming area is on the marshy bay side of the island and is called Marennes-Oléron after the nearby mainland town of Marennes. The last photo in the slideshow is one that Walt took of an oyster dinner we had in our gîte on the island.
The oysters that are farmed in France are not a native European species; those are flat-shelled oysters (huîtres plates). The cultivated ones are "cupped" oysters (huîtres creuses — scientifically, Crassostrea gigas) from the Pacific Ocean (huîtres japonaises), which account for most of the production worldwide. They are hardier than the flat-shelled oysters (Ostrea edulis) that are native to French waters (called belons after a coastal river in Brittany).
French oyster-farming accounts for about 90% of total European oyster production, and very few French oysters are exported. The oysters are "raised" off-bottom, on tables or trestles that are covered by seawater at high tide and left high and dry at low tide. Often they are kept in mesh bags. Letting them grow on the sea bottom and then dredging for them is a less common practice than it used to be because bottom-dwelling oysters are more vulnerable to predators, including starfish, and diseases.
Before the oysters are put on the market, they are transferred to man-made salt ponds (claires) along the coast and left to fatten up for a few weeks. Leaner, less meaty Marennes-Oléron oysters are called fines de claires, and fatter, meatier oysters are called spéciales de claires. In France, oysters are almost exclusively served and eaten raw, on the half-shell.