In Norway, the Atlantic salmon parasite Gyrodactylus salaris was introduced through transfers of salmon and trout from Sweden in the 1970’s and quickly became the most acute threat to wild salmon in the country, capable of extirpating entire river populations in four to six years. 

The parasite eventually spread to 50 rivers and Norwegian authorities began a campaign to eradicate the parasite by denying it a host. Live gene banks and milt banks were established and entire rivers were treated with rotenone, removing all wild salmon. Among the largest was the Rauma River, which was treated in 2014 and subsequently declared parasite free.
 

To date, of the 50 rivers infected with Gyrodactylus salaris, 32 have been declared parasite free and salmon have been reintroduced, 11 others have been treated and are awaiting final analysis while seven rivers remain infected. Through the use of rotenone, the eradication of Gyrodactylus salaris in Norway is possible.