The leech-like parasite, Gyrodactylus salaris is a salmon killer. It naturally occurs in Russia, Finland and Sweden where it seems to do relatively little harm to salmon. However where it has spread to Norway it has caused devastation to the salmon stocks which appear to be genetically ill-equipped to tolerate its affects. It is very likely that the UK/Ireland salmon population would be similarly affected and it is therefore a very major threat.

Avoiding infected rivers is of paramount importance, and this applies to all river users, not just fishers, but canoeists and even bathers. The 46 rivers in Norway that are infected or have been infected are listed below, however the famous Norwegian salmon rivers such as the Tana, Namsen, Gaula and the Orkla have not been infected, and rightly have strict controls in place whereby visiting anglers must have their equipment disinfected (usually with Virkon) before fishing. Is it time we put these measures in place on our rivers? The only effective treatment of an infected river (known to date) is the complete poisioning of all fish life.