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Gyrodactylus salaris

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Gyrodactylus salaris

Gyrodactylus salaris is a parasite which infects the skin, gills and fins of salmon, trout and some other types of fish in fresh water. It is less than half a millimetre in size, so small that it is barely visible to the naked eye. Despite this, it can cause serious damage in some strains of Atlantic salmon.

It can be transferred by fishing and canoeing equipment.

The Trust is extremely concerned about the potential for fish disease to render our rivers ‘no-go' areas for anglers, canoeists and other river users, not to mention the effects widespread disease would have on the fish population itself. To try and raise awareness of the problem the Trust, in Partnership with the Environment Agency, has produced warning signs [link to pdf of G.salaris warning board] that you will see around the catchment.

If you would like some of these boards (they are free!) to mount on your section of river please contact us.

Information on the Disease and how to avoid being the one that brings it in

Taken from Keep Fish Disease Out leaflet published by the Environment Agency and DEFRA

Disinfection procedures

Fishing Equipment

All fishing equipment should be thoroughly cleaned and then treated to kill any parasites by either:

  • Drying at a minimum temperature of 20°C for at least two days, or
  • Heating for at least one hour at a temperature above 60°C, or
  • Deep freezing for at least one day, or
  • Immersion in a solution suitable for killing Gyrodactylus salaris for a minimum of ten minutes.
  • Chemical solutions which have been used successfully include Virkon* (1%), Wescodyne* (1%), sodium chloride (3%), sodium hydroxide (0.2%).

*these chemicals are available from agricultural chemical suppliers. The use of trade names is for illustrative purposes only and does not signify endorsement of any particular product.

Canoeing Equipment

All canoeing equipment should be thoroughly cleaned and then treated to kill any parasites by either:

  • Submerging boats, spraydecks etc in SEAWATER for at least 10 minutes (ensuring there are no air pockets)
  • Drying at a minimum temperature of 20°C for at least two days, or
  • Heating for at least one hour at a temperature above 60°C, or
  • Deep freezing for at least one day, or
  • Immersion in a solution suitable for killing Gyrodactylus salaris for a minimum of ten minutes. Chemical solutions which have been used successfully include Virkon* (1%), Wescodyne* (1%), sodium chloride (3%), sodium hydroxide (0.2%).

*these chemicals are available from agricultural chemical suppliers. The use of trade names is for illustrative purposes only and does not signify endorsement of any particular product.

Why should I be worried?

The effects of the disease are so serious that salmon stocks have now been lost completely from more than 20 Norwegian rivers, with the particular races of salmon in the affected rivers being lost forever. Gyrodactylus salaris does not occur in UK rivers but experiments carried out in Norway have shown that our salmon, like those of Norway, are killed by the parasite. It is therefore essential that the parasite is not introduced into UK waters.

REMEMBER IT ONLY TAKES ONE INFECTED FISH TO START AN EPIDEMIC

What can I do to prevent G.Salaris infecting the Tyne?

This parasite is very hardy and may be inadvertently introduced by fishing, canoeing and any other equipment used in infected waters (e.g. Norway).

It is capable of surviving for several days in damp conditions such as plastic bags, wet angling equipment (e.g. bags, waders, landing nets, lines), wet canoeing equipment (e.g. spraydecks, boats, cags, throwlines) and the wet surface of dead fish (e.g. bait fish). The parasite can also survive on other fish species including the eel.

For further information please visit the Environment Agency web site and the Fisheries Research Services web site