Just when SVT Gävleborg went on a test fishing trip in the sea off Gårdskär, no butter balls were found, but Linda Calamnius who is a marine biologist and project manager at the County Administrative Board of Gävleborg is still worried about the results of the previous test fishing.
- It is an extreme find in our waters, says Linda Calamnius
What can these fish do?
- They compete with native species and can get up in freshwater and maybe eat salmon and trout rum.