Gyrodactylus Salaris Threat

Gyrodactylis on a salmon

The Scottish Executive has announced plans for dealing with Gyrodactylus salaris should it arrive on our shores. Gs is so lethal to our Atlantic salmon in its self however the consequences of the eradication treatment are even more devastating to life in a river system. The following extract from the Scottish Executive Working Group web page briefly describes what the threat is and how dangerous is. It also sets out the terms of reference for the Working Group which are chilling in that they will include the compulsory slaughter of all wild fish in an infected water system.

Extract from: http://www.scotland.gov.uk/Uploads/Documents/GsConplan.pdf*

*(you may need to download adobe reader) or click here

'Gyrodactylus salaris is a parasite which infects the skin, gills and fins of salmon, trout and some other types of freshwater fish. The parasite is less than a half millimetre in size, and is barely visible to the naked eye and can cause serious damage to some strains of Atlantic salmon. The parasite is very hardy and may be introduced by fishermen as it is capable of surviving for several days in damp conditions such as plastic bags, wet angling equipment and on the surface of dead fish. Gyrodactylus salaris occurs naturally in the Baltic rivers of Finland and Russia, where the native fish are tolerant to the parasite and normally any infection causes them no harm. In areas where the parasite does not occur naturally, salmon trout and other freshwater fish have little or no tolerance.

In Norway between 1970 and 2002 salmon stocks on 44 rivers have been infected as a result of infection by Gyrodactylus salaris. Means to eradicate the parasite are very costly. The Norwegian remedial work is very destructive and this work has involved treating whole catchment areas.

At present the UK is free from this parasite, and in order to ensure that it remains so, a Working Group has been formed. This group will also look at the various ways in which the parasite can be contained and eradicated, should it ever appear in the UK. A news release giving notification of this was issued on 31 August 2005.

The group has the following terms of reference:


  • Develop preventive measures at home and abroad to exclude GS from Scotland
  • Produce a contingency plan to contain and where possible eradicate the parasite should it be introduced to Scotland
  • Identify the personnel who would form the skeleton of a control organisation and the preparation and training they require such as secondment to Norway.
  • Consider other options for intervention including employment of the Norwegian company VESO and recommend accordingly
  • Where control is impractical, to make recommendations for measures to minimise the spread of Gs and mitigate its impact on freshwater fish and the wider economy.
  • Identify and develop proposals for new statutory controls, including necessary powers for compulsory slaughter of wild fish, prohibiting abstractions of water during a river treatment, provision of alternative water supplies for watering livestock and movements of live fish.
  • Identify research needs for the identification of Gs, containment and control measures such as determining the efficacy of disinfectants and investigation of the chemistry of Scottish rivers in preparation for the use of aluminium sulphate
  • Investigate with representatives of Scottish smolt producers the questions of the industry providing gene bank facilities for use in restocking rotenone treated rivers.

The announcement on the 8th of December 2006 means that a contingency plan is now in place however the necessary draconian measures cannot be implemented until the Scottish Parliament amend the Aquaculture and Fisheries (Scotland) Bill.

Modern transport makes it easy for anglers to fish all over the world. This globalisation of angling makes the transmission of foreign parasites as easy as jumping on a jet. For this reason we must take extraordinary precautions on our return from fishing trips to areas where Gs infestation is suspected. These precautions include meticulous sterilisation of all fishing gear used in the trip including clothing.

It is not just the angling fraternity that must be meticulous, anyone participating in water sports e.g. canoeist, must ensure that they apply the same procedure for sterilising their gear.

The following extract from the Association of Salmon Fishery Boards describes the measures you must take to ensure that your equipment is safe to use on your return from a foreign fishing trip.

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

'DRYING AT MINIMUM TEMPERATURE OF 20 DEGREES CELSIUS FOR AT LEAST TWO DAYS HEATING FOR AT LEAST ONE HOUR AT A TEMPERATURE ABOVE 60 DEGREES CELSIUS DEEP FREEZING FOR AT LEAST ONE DAY, OR IMMERSION IN A SOLUTION SUITABLE FOR KILLING GS 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%). IT IS RECOMMENDED THAT ALL EQUIPMENT SO TREATED SHOULD BE ACCOMPANIED BY A VALID CERTIFICATE FROM THE RELEVANT FISH HEALTH REGULATORY AUTHORITY IN THE COUNTRY OF ORIGIN OR AT THE POINT OF ENTRY INTO GB.'

The Scottish Executive Rural Affairs Department, in conjunction with the Department for Environment, Food and Rural Affairs, has produced a code of practice to avoid the introduction of GS into Great Britain. It is strongly recommended that this is consulted, and a copy is available on the Fisheries Research Services. Hard copies of the code of practice may be obtained from FRS by calling +44 (0) 1224 876544'

It is essential that you follow this advice because it could be you who brings devastation to these shores. The horrors of foot and mouth are still clear in our minds. An infestation of Gs in this country would be the aquatic equivalent. Just to paint the picture in bold, visualise standing on the banks of your favourite river after the rotenone treatment has been applied. Every fish in the entire river killed, yes every fish from source to sea. For this reason the authorities are investigating having smolt producers provide a gene bank so that infected rivers can be restocked. With Gs the cure does involve killing the patient!

 

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