Salmon under threat from new killer bug

Published on Sunday 1 February 2004 00:00

THE king of fish is facing a new threat. A deadly parasite that could devastate stocks of wild Atlantic salmon is on the verge of spreading to Scotland.

The gyrodactylus salaris (GS) parasite has already wiped out wild salmon in at least 20 rivers in Norway and has infected fish in Sweden, France, Denmark and Germany.

Now fisheries experts fear that visiting anglers could bring the parasite back into Scottish waters, with serious consequences for both the salmon and the communities that rely on the income they bring in.

Fishing for salmon is a mainstay of the economy along the banks of rivers such as the Tweed, the Tay and the Dee.

The Scottish Executive will tomorrow launch a campaign to warn returning anglers to thoroughly clean their fishing equipment to prevent GS infection.

Allan Wilson, the deputy minister for the environment, said: "If the GS parasite were to be introduced into our waters, entire river systems could quickly become infected, with serious consequences for valuable freshwater stocks of salmon.

"It is possible that the parasite could be brought in on fishing equipment or clothing, so it is vital that anglers who have been fishing abroad are warned of the dangers and reminded of the precautions they should take to ensure that their fishing equipment is not contaminated."

The parasite, which has no effect on humans, is a serious fish disease affecting the gills, skin and fins of salmon and some other freshwater species. It occurs naturally and harmlessly on wild salmon in Finland and Russia, but is believed to have spread to Sweden and Norway where fish have no in-built immunity.

Wild salmon stocks have now been lost completely from a large number of Scandinavian rivers. Tests have revealed that British salmon stocks are equally susceptible. Once the parasite infects a river system, it is difficult to eradicate. The whole catchment area has to be chemically treated, an expensive method with no guarantee of success.

Experts say the parasite is very hardy and so may inadvertently be introduced by anglers. It can survive for several days in damp bags or on the surface of wet fishing equipment. Anglers returning from fishing abroad are being urged to ensure their equipment is disinfected with commonly available chemicals.