BOURCEFRANC-LE-CHAPUS, France — For Thierry and Veronique Gillardeau, the oyster has become their world.

A member of the fourth generation of a family of oyster farmers, Thierry, 37, has brought an economics education to what has become the most famous name in oysters: Gillardeau.

The Gillardeau family’s small private company, founded 110 years ago here by the sea near La Rochelle and the Ile d’Oleron in western France, produces only “speciales,” oysters that are fleshier and, consequently, more expensive than the standard.

The Gillardeau name has become associated with fine oysters, rather like Hermes for neckties.

Thierry’s father, Gerard Gillardeau, 61, took over the business from his father, Jean, who ran it after his father, Henri, who began as an illiterate farmhand before turning his hand to oysters. Oyster farming then dominated the economy of the region, where the Charente and Seudre Rivers add their fresh water to the salt flats and estuaries.

Henri did well enough to build a large house opposite City Hall in this village of 3,500 people, a house he called “Ca m’suffit,” or “That’ll do.” Thierry and Veronique live there today.

Many of the neighbors still farm oysters “the way they did in the Middle Ages,” he said, by taking the seedlings to full growth in small oyster basins next to the sea, farming them in small, flat-bottomed boats and doing much of the work by hand. “They could be more profitable,” he said. “But the past is so important to them that they don’t want to change.”

That attitude makes the Gillardeau family something of an anomaly in a nation famously resistant to change, especially in how it produces food and wine.

In 1978, Gerard sought to expand beyond his village and found a partner in the huge wholesale market in Rungis, just outside Paris, a step that helped the Gillardeau company make a name for itself. For the past 15 years, sales have increased roughly 20 percent a year, Thierry said at a conference in May. As a private company, it does not reveal its accounts.

Unlike many other companies, Gillardeau buys seedling oysters that are 1 to 2 years old. That way it avoided most of the impact of the widespread death of younger French seedling oysters this year, believed to have been caused by a warm winter, heavy spring rains and possibly excess runoff of fertilizer and pesticides.

Maximum quality

To protect the future, Thierry bought 20 million seedlings unaffected by the blight at a premium in Ireland, where the company will raise them itself.

Gillardeau normally farms the 2-year-old oysters it buys for the next two years, coaxing them into a shape like a lemon and maximizing the quantity of the flesh by carefully adjusting the depth and salinity of the water. The company tries to keep its oysters from clumping together, putting 135 to 150 oysters in each of the plastic-screening sacks that can hold 1,000.

Workers with tractors turn the sacks every two weeks or so, to break the small shells that the oysters produce, to “stress” the oyster to eat more and to grow in the desired form. “You shape an oyster a little like a piece of furniture,” Thierry said.

Before a batch is packed, one Gillardeau or another makes sure to taste a few oysters. Theirs are less briny than many others’ — nuttier, fleshier, almost sweet.

Bernard Jaulin, 57, gave up oyster farming nine years ago with great regret. He is now remodeling a bar-restaurant he bought in nearby Fouras. “Now it’s different,” he said. “It’s bigger, more modern, more technological.” The local oyster beds, he said, “don’t give any more.”

Asked about Gillardeau, his eyes lighted up. “Have you tasted them? The taste is exquisite. They have that extra body,” he said, crunching his jaws.