Uses chlorine to clean the river Driva of the salmon parasite Gyrodactylus salaris – news Møre og Romsdal – Local news, TV and radio

The parasite Gyrodactylus salaris has plagued life in Norwegian salmon rivers since 1975. Then infected salmon from Sweden were released into Norwegian rivers, lakes or freshwater fish production facilities. The parasite then spread to salmon fry in 50 Norwegian rivers. Today, only the Drivavassdraget and the Drammensvassdraget are infected. After several decades of treatment, the Norwegian Environmental Protection Agency believes that the battle against the deadly parasite may soon be won. The gyroparasite attaches itself to salmon fry and can wipe out an entire population. Photo: Kjetil Opstad Harms only the parasite This week the treatment of the river Driva begins with a hitherto unused method: Chlorine. – It is very exciting and spectacular. We are now starting the treatment of the penultimate region with gyro in Norway, says Jarle Steinkjer, project manager at the Norwegian Environment Agency. The great advantage of chlorine is that it does not harm anyone but the parasite, neither fish nor benthic animals. In comparison, the widely used rotenone treatment kills all life with gills. Usually used for drinking water The authorities have spent a staggering one billion kroner to overcome the parasite. For almost ten years, researchers from the Norwegian Institute for Water Research (NIVA), the Veterinary Institute and the Norwegian Institute for Nature Research have collaborated to develop the chlorine method. Chlorine is usually used to treat drinking water, and the chlorine content in the river is no higher than in the drinking water in Oslo. One teaspoon per 5,000 liters of water is enough to eradicate gyro from the students. – We are not aware that anyone else has ever done this. We use a treatment method for drinking water in a new way, says Anders Gjørwa Hagen, project manager at NIVA. From the very beginning of the 80s, attempts have been made to eradicate the parasite with chemical treatments. Anders Gjørwa Hagen, Helge Bardal and Jarle Steinkjer have succeeded with chlorine. Photo: Eirik Haukenes / news Spreading widely A report from the Norwegian Institute for Natural Research concludes that the work to eradicate the parasite in infected rivers is a great and unique success, both nationally and internationally. In the Drivavassdraget, streams and several neighboring rivers are also to be treated, but not all are suitable for chlorine treatment. – We are starting in parallel with rotenone treatment of the rivers Usna and Vatnefjordselva, and several small pupils in the fjord system, says Helge Bardal, project manager at the Veterinary Institute. Will release fry Over one hundred people participate in the work. At the same time as the fight, work is being done to ensure that the genes of the sea trout and salmon are taken care of. The goal is for Driva to return to what it once was. – We must release salmon and sea trout here until probably well into the 2030s, says Bardal. Helge Bardal is project manager at the Veterinary Institute. Photo: Eirik Haukenes / news



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