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Dieren en planten

Bivalves   Oysters   Flat oyster   Pacific oyster   Bivalves   

Flat oyster


up to 15 centimeters


white to grayish




disease, parasites, people



  • Dut: Platte oester
  • Lat: Ostrea edulis
  • Eng: Common European oyster (European flat oyster)
  • Ger: Europäische Auster
  • Fren: Hußtre
  • Dan: Flade østers
Flat oyster, foto fitis, sytske dijksen

Flat oyster

There are very few wild flat oysters around anymore. They have become rare due to disease and competition with the Pacific oyster. The oyster shells on the beach are usually remnants from very old animals, dead already for many years. The shell has a rather regular shape, in contrast to the Pacific oyster which can have all kinds of sharp protrusions. The flat oyster is edible. For some people it is only a slimy bunch of salt but, according to oyster-lovers, it is the most delicious thing ever.

On Texel

There were oyster farmers on Texel up to the beginning of the 20th century. Texel oysters were famous in the 19th century. The flat oyster disappeared in the entire wadden region in the past century due to freezing temperatures and disease.

  • Distribution and habitat

    The flat oyster lives on hard surfaces down to depths of 80 meters. In the Dutch seas, the flat oyster has become more or less extinct due to overfishing, diseases and competition with other species, such as the Japanese oyster.

  • A sickly mollusc

    Oyster farmers often have to deal with diseases among oysters. Until 1995, there were always a large number of deaths somewhere caused by the one-celled parasite Bonamia ostreae. This disease appeared in the beginning of the 1980s in the oyster stock in the Oosterschelde and eventually destroyed most of the oysters in the Grevelingen. The disease was probably imported along with oysters from Brittany, which in turn were infected by imports from California.

    In 1996 and 1997, the death rate due to Bonamia ostrea appeared much less than in previous years. A different disease broke out in May 1996, killing many oysters once again. This time, the flowering of the harmful algae Hexabita was most likely the cause. In 1998, the disease caused by Bonamia ostrea appeared 3.5 times more often than in 1997.

    These kinds of illnesses are not only harmful for the oysters on aquaculture beds. Wild oyster populations also decline strongly from harmful algae.

  • Oyster farming in Zeeland
    oesterbedden in Zeeland, 1912, foto fitis, sytske dijksen (de Prins)