Public Release: 

Why Are The Fish Sick? Local Tip Suspected

Swedish Environmental Protection Agency

What is causing the extensive damage to fish in the small Swedish lake "Molnbyggen" . In order to determine the cause the Swedish Environmental Protection Agency (SEPA) has stepped in to work with the municipality of Leksand in Central Sweden. It is believed that endocrine disrupting substances, leaked from a nearby landfill are to blame.

The damage was discovered by local people four years ago. This led to an extensive study by a group of researchers from the Institute of Applied Environmental Research at Stockholm University. They found that up to 30 per cent of the fish in the lake showed signs of damage, including open wounds and fin deformations. However, the most pronounced biological effect was the underdeveloped ovaries found in female fish, affecting reproduction. The ovaries in female perch were 80 per cent decreased compared to female perch in a control lake. Some male fish also suffered hormonal damages.

It is not yet clear which substance or substances are involved, but evidence points increasingly to a public landfill site located 3-4 kilometres from the lake Molnbyggen. SEPA and the local authority have decided to carry out a thorough investigation of the problems.

"We are stepping in to help Leksand municipality, partly to trace the substances as quickly as possible. But also to determine what consequences the environmental damage in Molnbyggen can have for other landfill sites in the country", says head of section Björn Södermark at SEPA.

"The results from Molnbyggen can also provide important information in our current work with waste treatment and disposal, including new general guidelines and tighter regulations for landfill disposal," he adds.

Head of the environmental health department in Leksand, Olle Bergfors, comments: "We are positive towards the Environmental Protection Agency stepping in to support our investigation. So far, the local authority has invested SEK 1 million in the project. With their help, we hope to get a broader picture as well as a quicker answer."

SEPA has already commissioned a study of hydrological conditions in the landfill site and there is strong evidence that a small amount of leakage is seeping through the topsoil layer. This supports the suspicion that the landfill is to blame.

The current investigation has been divided into ten separate studies. In one study, researchers will carry out further investigations into what might cause the disturbances in the fish. One theory is that pesticides could be the cause. Another project will therefore concentrate on looking into the use of such products by local businesses, drawing up a list of possible pollutants. These will then be analysed in leakage, lake water and sediment and tested on the fish.

Other studies include alternative handling of the leakage from the landfill site, controlling and stopping leakage, a survey of the landfill site and a general description of leakage and sediment, information to the public and scientific review.



  • Olle Bergfors, head of environmental health department, Leksand municipality; project leader. Tel: +46- 247-80329
  • Fredrika Norman, project leader, Swedish Environmental Protection Agency, Tel: +46- 8-698 1224,
  • Björn Södermark, head of department, Swedish Environmental Protection Agency, Tel: +46-8- 698 1141,
  • Lennart Balk, ass. prof., Institute of Applied Environmental Research, +46-8-674 7721, 070-4470008,

Press Service:

Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.