The most popular oyster in Europe is the European flat oyster, which is the only oyster variety naturally found in Norway. In addition, the Pacific oyster has been found along the south coast of Norway and in the country of Hordaland. The flat oyster is found in waters heated by the sun and in shallow waters northwards to Trøndelag. A water temperature of about 15 degrees is necessary for the oyster to change from male to female. The oyster builds up roe and milk from spring to the spawning period in the late summer, but only spawns if the temperature is high enough. The eggs are fertilized inside the shell, and the larvae stay inside the shell the first week before leaving the mother. When they leave, they swim freely until they attach themselves to the bedrock where they will remain. Larvae are also produced in hatcheries, or in a combination of hatcheries and oyster tanks. The European flat oyster can live for more than 20 years, although the normal lifespan is between 8 and 10 years.
Norway harvests only small quantities of wild oysters, and these are harvested by divers or with rakes with landing nets. Oysters are in season year-round, but are considered to be at their best from autumn to spring.
Flat oyster is sold as following products:
Plankton, microalgae, organic materials
Oysters are especially rich in:
- Protein that builds and maintains every cell in the body.
- Vitamin D, necessary to balance calcium in the body, which maintains and strengthens the bones.
- Vitamin B12, which is important for the body to produce new cells, including red blood cells. Vitamin B12 can contribute to preventing anaemia.
- Selenium, an important element in an enzyme that fights harmful chemical processes in the body.
More nutritional data can be found at www.nifes.no/en/prosjekt/seafood-data