Way of life


The flounder mates at a depth of between 20-40 metres from February to May in the southern and south-eastern North Sea. In the western Baltic they mate even deeper, 40-100 metres, and require a salinity of at least 1%. At lower salinities the eggs sink to the bottom and often go to waste. The female lays between 400000 and 2 million eggs. Egg size varies between 0,8-1,4 mm (the larger being in brackish water) and are pelagic. Hatching takes place after 5-7 days at a temperature of about 10°C. Before falling to the bottom in shallow water, the larvae grow from 3 mm to between 7-10 mm. At the age of one year the flounder is about 4 cm long around Bornholm and about 13 cm in the Kattegatt. Independent of size, the males became sexually mature after 3 years and females after 4 years.


The majority of flounders turn their right side upwards, but up to a third can be left-sided. In areas where the flounder mates at the same time as the plaice, mutations occur that are less hoarse than the flounder and with red spots that are not as apparent as on the plaice.
    The flounder is fished with ordinary nets, hoop nets and purse seines. It is usually sold fresh or smoked. Several countries have imposed fishing restrictions pertaining to size and season.

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What it eats



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