Three Dutch and one German shrimp processing firms have ben fined a total €28.7m for cartel forming, with the biggest fine – €27m – going to Heiploeg.

The European Commission investigation found the companies had for years fixed the prices of North Sea shrimps, leading to too-high prices for consumers.

In a statement, competition commissioner Joaquín Almunia said: ‘It is astonishing to see in what kind of detail North Sea shrimp traders in their frequent contacts with each other discussed commercially sensitive information concerning their business.

‘And it is even more astonishing taking into account the sector had already received a clear warning via the previous conviction of some traders by the Dutch competition authority.’

Between them, the four firms controlled some 80% of the European North Sea shrimp market. Heiploeg, based in the small town of Zoutkamp in Groningen, is European market leader.