Seven lakes in Bymarka in Trondheim municipality forms an island population for further spread of the blacklisted carp fish roach (Rutilus rutilus) to new locations in central Norway. Further spread to the Trondheim and Malvik municipalities main drinking water source (Jonsvatnet) are considered large and real. In 2013 a dense population of roach was detected in Vikerauntjønna, a lake located only 250 m from the drinking water source. Vikerauntjønna was treated with rotenone in the autumn of 2014. There is concern that the roach can affect water quality adversely.
Rotenone treatment is considered as the only measure which could remove roach from the lakes in Bymarka. The treatment will remove the current threat to the drinking water supply, while it will prevent the spread of unwanted species across the region and contribute to conserving natural fish stocks and biodiversity.
The following seven lakes in Bymarka have roach: In Ila watershed: Kobberdammen, Baklidammen and Theisendammen. In Leirelva watershed: Kyvatnet, Lianvatnet, Haukvatnet and Sølvskakkeltjønna.
The Norwegian Veterinary Institute, Environmental and Biosecurity Measures, will eradicate roach from Bymarka using the rotenone solution CFT Legumine. The Norwegian Veterinary Institute is responsible for finance, planning, processing and reporting.
Project manager
Partners and funding
Trondheim municipality