Invasive Species Sea Bream Spreads in Southern Sweden
Sea bream, an invasive plant species, has been causing concern in Southern Sweden as it continues to spread in large parts of the region, including Östergötland, Västmanland, and Västra Götaland. The sea and water authority has reported that the plant has even reached Lake Mälaren.
The issue of sea bream in Hökerum, northeast of Borås, is not new. It was discovered in the Viskan river about fifteen years ago, and since then, the municipality of Ulricehamn has been trying to find funds to combat its spread. Jan-Erik Magnusson, a resident of Hökerum and part of the community association involved in the initial prevention efforts, recalls installing rubber mats many years ago to prevent the spread of sea bream.
Sea bream, which has small water lily-like leaves and bright yellow flowers, appears innocent but has proved to be harmful to the environment. Once attached, it forms a carpet-like layer on the water’s surface, preventing sunlight from reaching the bottom and suffocating other plant life, such as water lilies. This effect is clearly visible in Hökerum, where sea bream has become a significant issue.
To combat the growth of sea bream, the County Administrative Board in Västra Götaland recently laid out aluminum frames in the Viskan river. These frames are covered with a canvas that shades out the light, ultimately causing the sea bream to die. Anna Dimming, the coordinator for aquatic invasive species at the County Administrative Board, expects the frames to remain until next summer to ensure their effectiveness.
Kenneth Karlsson, a summer house owner in Hökerum, applauds the initiative taken by the County Administrative Board. He believes the frames are necessary because the growth of sea bream has become uncontrollable and threatens access to the river.
The use of frames to control sea bream has proven effective in other counties. However, it is a relatively expensive method, with each frame being quite costly. Therefore, early detection and prevention are vital to minimize costs. The frames are expected to be moved downstream once the desired results are achieved.
Jan-Erik Magnusson, a retired green area manager in Hökerum, also expressed concern about the spread of sea bream and emphasized the importance of addressing the issue before it gets out of hand.
Currently, sea bream does not appear on the EU regulation of invasive species. However, the Sea and Water Authority and the County Administrative Board have invested funds to combat its spread. The Norwegian Sea and Water Authority has submitted a proposal to the government office to include sea bream on a national list of invasive species, which would enable clear prohibitions and systems for supervision.
As the battle against sea bream continues, it is crucial to find effective and cost-efficient methods to prevent further spread and protect the ecosystem of Southern Sweden’s waters.