The oyster farming takes place on the Eastern Scheldt Estuary (called “Oosterschelde”), of which the centre is the town of Yerseke (population about 6,000 as of 2004.) This area is the only place in the Netherlands where oysters are grown and harvested commercially, aside from a small area in the Wadden sea in the northern part of the Netherlands.
The sea farming plots are owned by the state and rented out by oyster farmers who seed and raise the oysters in their allotted plots. The oysters are harvested with a dredger. Oysters below 2 oz (60g) are returned to the water to keep on growing. The oysters retained are transferred to concrete ponds with sea water constantly pumped through. This helps to clear the oysters of the mud and grit inside them. After a few days, the oysters are then sold to markets.
Several varieties of oysters are raised:
Gigas Oysters have long, irregularly-shaped shells, and are hard to open. They belong to the Pacific (Crassostrea gigas) species of oysters, so they are most often referred to as “Pacific” oysters. They need 3 years of growth to reach marketable size.
Fine de Claire Oysters
Fine de Claire Oysters eat an algae which is somewhat blue in colour, giving the same colour to the oysters. They have an aftertaste that is almost sweet. They are also cultivated along the French coast. These oysters also belong to the Crassostrea gigas species of oysters.
The flat oysters raised in Zeeland are actually Bélon oysters (Ostrea edulis), originally brought in from Riec-sur-Bélon, France. Flat Oysters need 4 to 5 years of growth to reach market size, about 70 to 100g.
The larger Pacific Oysters represent the majority of oysters being raised in Zeeland. Though they are regarded as too large and tough to be eaten raw “on the half shell”, as gourmets prefer to eat oysters, they are popular with consumers because their bigger size makes them easier to grill or bake. And, more importantly, they are immune to the Bonamiasis disease which wiped out the Flat Oyster populations in the recent past (see History.)
Zeeland Flat Oysters sell for 5 times the price of Zeeland Pacific Oysters, so they are separated out from the others at harvest.
To open flat oysters: wrap in cloth, hold in hand with the hinge pointing at your thumb. Insert knife inside the oyster, move towards the hinge.
To open Pacific oysters: wrap in cloth, place on table or counter, put knife right into hinge, and twist to break the hinge.
Oyster fishing on the Oosterschelde coast took off in the 1800s. By the 1860s, though, overfishing caused the natural stocks to collapse.
The Dutch government decided to lease out plots of what had previously been public seabeds, with a view that the renters would cultivate oysters and look after the stocks better. Leasing began around 1870, with the first harvest of cultivated Flat Oysters occurring in 1875. Though the oyster stocks sprang back, an unfortunate side effect was that many of the local fisherman were put out of business, because the plots were leased by companies or individuals with enough money to procure the plots.
By 1906, the Dutch also instituted quality and safety controls on the oysters being harvested.
The Flat Oyster populations in Zeeland were decimated by a severe winter in 1962 – 63. In 1964 Pacific oysters were introduced “temporarily”, until the Flat Oysters had a chance to recover. It was assumed that the Pacific Oysters wouldn’t be able to breed in the colder water of the Netherlands.
By 1976, however, it was found that the Pacific Oysters had not only adapted, but that they were reproducing on their own in the wild. Importation was halted, and by 1982, the Pacific Oyster population had exploded and firmly established itself. The Flat Oyster population received another crippling blow in the early 1990s with the introduction of Bonamiasis disease by contaminated French oyster seed, to which the Flat Oysters were susceptible. The Pacific Oysters were immune.
In 1989, roughly comparable numbers of 5,373,000 Flat Oysters and 5,309,000 Pacific Oysters were harvested. After the outbreak of the Bonamiasis disease, however, in 1992 only 138,000 Flat Oysters were harvested, compared to 10,485,000 Pacific Oysters.
Pacific Oysters are now competing and winning against even cockles and mussels. They are called “wild oysters”, because are doing very well even without cultivation.
The latest figures available (2002) show 754,000 Flat Oysters harvested, compared to 27,891,000 Pacific Oysters.
Researchers in the Wadden sea area (northern coast of the Netherlands) are working on developing disease-resistant Flat Oysters.
Literature & Lore
“The importer tells us that mussels are found abundantly along the shores of western Europe, but are so irregular in size that they present a packing problem. By farm-raising, the mussels can be grown to the exact size desired. Every year the mussel firmers visit the rich, natural beds along the Dutch shores and dredge for the young to use for their seed. These are taken to the Province of Zeeland and scattered over mussel banks in deep waters leased from the government. Once again, before harvest, the mussels are dredged and scattered on new locations for a final fattening. It takes from one to two years for the mussel to reach the desired processing size…
Dutch mussel beds are inspected by government bacteriologists at regular periods, and this shellfish goes to market as our oysters do with certificates of purity.” — Paddleford, Clementine (1898 – 1967). Food Flashes Column. Gourmet Magazine. June 1950.