Extensive farming

Extensive farming entails that the larvae are caught from wild oysters. It makes large demands on the availability of natural larvae.
  Already in 200 B.C., larvae were caught in southern Europe by placing out bunches of twigs, and afterwards the collected larvae were placed in salt water ponds and given a continual supply of water and food. This technique is still used today, but the larvae collectors limewashed nowadays.
   In Norway there are natural conditions that enable farming using a special technique. There are many small, shallow and nearly enclosed bays, known as "polls", that during the summer became surprisingly warm. In the beginning of April, cages with the breeding oysters, are placed at a depth of between 2-3 metres, where the water is warmest. Between June and July, the larvae are collected on the bunches of twigs that hang at the same depth. In this way, oysters have been farmed in Norway since 1880.
   In Sweden, using imported larvae, oyster farming has been practiced for more than 100 years. Probably the most successful farming operation was between 1934-39 in the Stigfjord between Orust and Tjörn, but the second world war and cold winters have stopped the operation.

Intensive farming

Intensive farming entails that wild oysters are reproduced and grown in land based farms. The larvae are grown under good conditions that promote rapid growth and survival, and offer a suitable bedding for when the free swimming stage ceases. After a few months they are placed in the sea until they reach a commercial size, 7 cm in 3 years. At the Tjärnö Marine Biological Laboratory a project to try and farm oysters intensively is in progress, but at present, researchers need to find out more about the mechanisms that steer the survival of free swimming larvae. It appears that the composition of unsaturated fatty acids is decisive.

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Ancient food

European oyster

Giant Japanese oyster

Other specie

Royal dish

Varying catches


Extensive farming

Intensive farming

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Bo Johannesson | Martin Larsvik | Lars-Ove Loo | Helena Samuelsson