«FOREWORD This Code of Practice (CoP) represents the culmination of months of effort by a dedicated number of individuals from within the industry and ...»
What are the risks associated with diving?
Divers encounter high-risk organic material on a daily basis. This material and all their equipment pose a risk of transferring disease.
How can the risk associated with diving be minimised?
• Remove organic material from all suits and equipment;
• Immerse suits and equipment in fresh water containing iodophor (minimum 100mg/l free iodine) for 20 minutes or heat treat by immersing equipment in clean fresh water so that the gear is maintained at a temperature higher than 55 °C for at least 5 minutes;
• Rinse thoroughly with clean fresh water;
• These specific disinfection routines for divers must be implemented and should be audited and documented by site staff on each occasion.
6. HARVESTING OPERATIONS What are the risks associated with harvesting operations?
Risks are from proximity to infected farms, harvest stations or slaughter houses and from the movement of infected live or dead fish, contamination with blood, body fluids and offal, equipment and personnel.
How can these risks be minimised?
• Separation distances. Production units must not be sited within 5km or one tidal excursion (whichever is greater) of a harvest station or, in the case of processing plants, unless effluent disinfection has been installed.
• Containment and disinfection. It is a requirement under the Welfare of Animals (Slaughter and Killing) Regulations 1995 that fish must be dead or deeply unconscious when their gills are cut. Compliance also reduces blood splashing which is beneficial from a disease containment perspective. Gill cutting must take place on a facility where the blood water can be caught and disinfected. This may mean using guttering and bins particularly when slaughtering at sea. The use of covers to reduce volume variations caused by rain is
required when these processes occur in the open. At the end of each day, all equipment requires disinfection according to the SDP2.
• Risk of escapes. Before commencing harvest at sea or transporting fish from a farm to a harvest station, the cage net should be examined for holes or signs of weakness. This should be carried out before crowding the fish. The method of crowding the fish and removing them to the slaughter point should be assessed for risk and contingency arrangements made to prevent fish escaping. Examples of the types of contingency arrangements are the establishment of a ‘safety net’ system to catch fish escaping from the lifting method (braille bags should not be operated outside the area of containment) and a hand net to recapture fish lost at sea from the killing table.
• Uplifting and transportation of harvested fish. Risk reduction measures should be directed at preventing
• Loss of harvest bins at sea by maintaining rafts in good repair, having contingency arrangements for poor weather conditions, ensuring harvest bins are properly loaded and secured and using harvest bins which are buoyant and therefore recoverable;
• Cross-infection by having a clear identification system in place for those harvest bins originating in high risk areas (for example, the use of colour-coded harvest bins) and ensuring that all harvest bins are subject to the SDP2 prior to re-use.
Plastic pallets should be used where possible and the use of wooden pallets phased out by treating them as ‘single-use’ only.
• On-site harvest stations. Additional risks associated with on-site harvesting arise from transfer of equipment and personnel between sites, and the vulnerability of some sites to adverse weather conditions. The
following risk reduction measures are specific to this type of harvesting operation:
• Rafts made of wood or other materials not readily disinfected should be avoided;
• Contingency arrangements for deteriorating weather should be in place before commencing harvest.
Rigorous procedures should be established to minimise the likelihood of damage from rafts, and equipment moored alongside cages. Blood water containment equipment should be covered to prevent the ingress of rain water.
• Harvest station at sea. Additional risks arise from the movement of live fish and the maintenance of a population of live fish at the station. Risks may be reduced by having permanent harvest equipment and containment methods, and by siting such stations in sheltered locations.
• Use of wellboats to move fish to harvest stations should be in accordance with this Code of Practice;
• The use of transport cages for moving fish from farm to harvest station should be limited to transport of fish through safe water over short distances within zones;
• To avoid attracting wild fish, there should be no feeding at a harvest station;
• Fish must never be transferred from a harvest station back to a production site.
• Shore-based harvest stations. The principal risks associated with this method of harvest are in the uplifting and movement of live fish and the disinfection of a large quantity of water from the wellboat. These facilities must make provision for disinfection of wellboat water or its safe disposal at sea.
7. PROCESSING OPERATIONS What are the risks associated with processing operations?
Reception and off-loading Risks include spillage in off-loading bays, either in routine tipping of harvest bins or in accidental ‘catastrophic’ release, for example, where a harvest bin bursts or falls. There may also be contamination of personnel (workers, visitors and/or passers-by) and contamination of vehicles which leave the site.
Effluent management, including blood water Contamination of personnel, equipment or vehicles by blood water or wash water leads to spread of disease, as does seepage of potentially infected material to ground water or water courses.
Waste solids Risks are associated with access by and contamination of vermin (for example, birds and rodents). The use of waste material as bait (for example, in creels) could lead to infection of new areas and/or the contamination of protective clothing.
Equipment and vehicles leaving the processing plant There is a risk of contaminated equipment, harvest bins or pallets (particularly wooden ones) being carried on vehicles leaving the facility. Spread of disease could also occur through the contaminated wheels and decks of lorries, and via workers leaving with contaminated clothing.
How can these risks be minimised?
Risk reduction methods:
• Off-loading bays must be equipped with a waterproof apron, draining to a collection point and should be surrounded by a bund or similar structure;
• Roofing over reception areas is recommended to avoid the problem of rainwater run-off becoming contaminated. Drainage from dirty areas must feed into a disinfection facility;
• Sprays or wheel baths must be available to treat vehicles leaving a site;
• Full protective clothing must be provided for staff and should be retained on the premises. The provision of disposable protective clothing should be considered where possible. Laundering of clothes should be at a temperature that will inactivate ISAV (at least 55°C for longer than five minutes). Rubber overalls need to be disinfected in a soak bath;
• Plastic pallets should be used whenever possible. The use of wooden pallets should be phased out. When wooden pallets have been used, they should be for ‘single use’ only;
• Site boundaries must be clear and access to dirty areas restricted;
• Processing areas dealing with high-risk material must be identified and restricted. All surfaces must be waterproof and amenable to disinfection, and drainage from dirty areas must feed into a disinfection facility;
• Waste solids must be ensiled before disposal.
What can be done to minimise the risks from escaped fish?
The conclusions and recommendations of the Farmed Fish Escapes Working Group3 must be followed.
• In addition, cage security inspection must be implemented immediately ISA is suspected or confirmed on a site, and a net inspection programme with increased frequency is followed until all fish are removed from the cages.
• Additional safety measures to prevent escapes must be implemented whenever ISA infected or suspected stocks are being moved.
• Particular effort must be directed at attempts to recapture escaped sexually mature salmon in line with any recapture methods proposed by the Farmed Fish Escapes Working Group.
9. OTHER BIOLOGICAL VECTORS OF ISAWhat are the risks from other ISAV vectors?
Fish. It has been suggested that sea trout may well be a natural reservoir of ISAV. Many species of non-salmonid fish have been examined and in Scotland ISAV has been detected in eel caught in fresh water and in saithe caught within a cage. While no evidence yet exists of infection in wrasse, the use of wrasse should be treated with caution.
Sea lice. Sea lice of both species (Lepeophtheirus salmonis and Caligus elongatus) have been demonstrated to transfer ISAV infection. The mobility of pre-adult and adult sea lice is well known and there may be a significant risk of transmitting ISA between sites.
Birds. The main risks from birds include passive viral transfer through body contact or the dropping of infective material and regurgitation of partly digested food.
Marine mammals. The biggest risk is thought to be from escapes resulting from nets damaged by predators.
How can these risks be minimised?
• The risk from wrasse will be reduced if use is restricted to those caught within the salmon farm’s hydrographically defined area.
• Synchronous sea louse treatments should be used without prejudice to environmental safety throughout a hydrographic area;
• There should be full enclosure of sea cages during bath treatments;
• Farmers should conduct weekly on-site lice inspections to select optimal timing;
• Regular compound resistance testing should be carried out;
• Post-treatment lice inspection should be carried out to verify efficacy of treatment;
• The use of hydrogen peroxide or other non-effective compounds should be minimised.
The risk of passive transmission of ISAV by birds should be minimised by:
• Attention to measures designed to exclude birds from direct in-cage contact;
• Good hygiene routines in handling mortalities;
• Good feeding practice which minimises wastage.
• The risk of damage to nets by seals should be minimised through the use of appropriate deterrent measures, for example, suitable net strength, acoustics and predator mesh.
10. AREA MANAGEMENT Management Areas and agreements within them are based on simple, yet fundamental aspects of the oceanographic conditions found in Scottish waters. They are able to take into account specific local conditions, and can also be applied widely to the entire Scottish industry. They should be adopted as the basis for dealing with outbreaks of any waterborne disease, as well as forming the basis for a sustainable and planned approach to managing the industry in the future. However, they must first be scrutinised on a case-by-case basis to take into account local conditions and planned occupancy of farms.
Guidelines on how to set up management agreements are given in the Final Report of the Joint Government/ Industry Working Group on Infectious Salmon Anaemia (ISA)1, but there are certain fundamentals that can be defined in this Code of Practice.
• Single year classes. Modern farming techniques mean that smolts can be transferred to sea water in virtually any month of the year and it is therefore important to define what is meant by a ‘single year class’. Figure
10.1 shows how the various combinations of S2 and S1 inputs should be managed to ensure a fallow period within a reasonable space of time. Subsequent stocking of S2 and S1s or vice versa is possible under these regimes.
• Fallowing. Dates should be agreed between all parties and should be obligatory.
• Health status of new smolts. There should be agreement on the quality of smolts to be stocked into a Management Area, which may include: physiological status of smolts; use of vaccines; and tests for specific pathogens.
• Good husbandry practices. These will be agreed by the participants but will include: adherence to stocking density limits; stock inspection; daily dead fish removal; veterinary input; proper disposal of dead fish (by ensiling in the first instance); net changing regimes; general hygiene and site cleanliness.
• Exchange of information. Information exchange may include: veterinary reports; mortality rates; timing and types of medicines used; and mutual inspections for assurance purposes.
• Tailoring an Area Management Agreement (AMA). In drawing up an AMA farmers may find that their situation does not easily fit into the template and that they will require a tailored Area Management Agreement. For example, to enable synchrony, farmers may agree to grow each other’s fish, or, in the absence of notifiable disease, farmers may choose to use a shorter fallow period of 4-6 weeks, or, in a case where a farm cannot fit into the required regime, it may have to close and efforts made to mitigate the loss.