Sea lice

RSPCA/RSPCA Assured position statement on the problem of sea lice:

  • We share people’s concerns regarding the very difficult challenge of sea lice. Sadly, there is currently no easy answer to solving this problem. Fish - whether farmed or wild - can suffer from sea lice in the same way that other farm animals and pets can suffer from parasites, such as mites and fleas, and need regular treatment
  • Reassuringly, the Scottish Salmon Producers Organisation (SSPO) recently reported that the number of sea lice affecting farmed salmon is at its lowest level in seven years (2020). However, this is not to say that it isn’t still a serious concern and it’s vitally important that all measures are taken to help reduce the risk of sea lice infestations
  • There is legislation in place that covers the management of sea lice - such as the Aquaculture and Fisheries (Scotland) Act 2007 - which all RSPCA Assured salmon members must adhere to 
  • The Act allows Marine Scotland Fish Health Inspectors to inspect sea lice records and assess the measures which are in place to prevent, control and reduce the numbers of parasites on farms. For example, adherence to the concept of Area Management Agreements and the synchronisation of treatments within these areas. If they are unhappy with any of the measures in place they have the power to insist upon enhanced inspections, issue advice, or implement enforcement action
  • In addition to complying with legislation, we require all RSPCA Assured salmon members to: 
    • Follow the National Treatment Strategy for the control of sea lice on Scottish Salmon Farms.  This is a robust framework for both counting sea lice and identifying when treatment interventions should take place. These provisions are contained in the Code of Good Practice for Scottish Finfish Aquaculture 
    • Draw up sea lice prevention and treatment programmes with their vet, which must be detailed in their Veterinary Health and Welfare Plan
    • Practise good husbandry, including fallowing, removal of dead and sick fish, and net cleaning.
  • But we want to go even further and are continually looking at new ways to help better manage the challenge of sea lice and improve the welfare of salmon. We are pleased to be part of a new working group for a project which will examine the effects of thermal delicing on fish health and welfare. The aim of the project - funded by SAIC (Scottish Aquaculture Innovation Centre) - is to further develop best practices for managing sea lice, whilst ensuring salmon welfare
  • We don’t claim that RSPCA Assured labelled salmon comes from farms that are always lice free. However, what we do claim is that it comes from farms inspected to 500 standards aimed at improving their welfare, and we are working with members and academics to find new ways to better manage the threat of disease and sea lice
  • As an animal welfare charity we believe we have a responsibility to be involved in trying to find solutions. Since the RSPCA and RSPCA Assured have been involved in the salmon industry, we have helped bring about many improvements to the welfare of farmed salmon and will continue to do so
  • If we walk away from the salmon industry because of the challenge of sea lice it could result in many millions of farm animals being reared to lower standards. And, as an animal welfare charity, we will not turn our back on helping improve the lives of farm animals.

What are sea lice?

    • Sea lice are naturally occurring external parasites which present a significant biological challenge to farmed Atlantic salmon (Salmo salar), similar to the way that fleas and mites affect pets such as cats and dogs
    • Sea lice attach themselves to fish using their mouthparts and feed on the outer layer of the skin 
    • Sea lice cause physical damage to the fish at the point of attachment and feeding, which results in abrasion-like lesions that vary in their nature and severity depending upon a number of factors, including the age and general health of the fish

How big a problem/challenge is sea lice in the salmon industry?

      • Sadly, sea lice can be a serious issue for farmed Atlantic salmon. Where there is an outbreak, sea lice can cause significant health and welfare problems for the fish. Where there is an outbreak, sea lice can cause significant health and welfare problems for the fish. However, the impression is often given that sea lice are a problem at all sea sites but, in our experience, this is not the case and they are in fact only a problem for a minority of salmon farms. There are some areas/sites where sea lice are not an issue, and chemical treatments have not been used for a number of years. This point was made in our written evidence to the RECC committee mentioned below and is quoted on p52 of the report.
      • According to the Scottish Salmon Producers Organisation (SSPO), the number of sea lice affecting farmed salmon is at its lowest level in seven years (2020)
      • To put this in context recent figures (September 2020) show that out of 211 seawater sites in Scotland (with 59 lying fallow), 23 of them experienced a sea lice problem which required treatment*. Therefore 15% of farms experienced a sea lice challenge. There is no data available relating to the severity of the issue on each site and how badly the welfare fish was affected prior to treatment.  
      • However, the relatively low proportion of farms affected is not to say that it isn’t still a serious concern and it’s vitally important that all measures are taken to help reduce the risk of sea lice infestations.

*Treatment would be triggered at the point of identifying either a half or one adult female louse per fish -this depends on the time of year.

How can sea lice be controlled?

        • Like parasites found on other animals, such as fleas on our pets, there is a range of control strategies that can be used by the aquaculture industry to help reduce sea lice infestation. 
        • Current methods of controlling sea lice include medicinal treatments, biological controls (such as the use of Cleanerfish) and the use of non-medicinal treatments, such as the Thermolicer and the Hydrolicer and freshwater treatments
        • Medicinal treatments - there are a number of authorised medicines used to control sea lice numbers.
        • These are administered either as a ‘bath’ or an in-feed treatment.
        • Biological treatments - increasingly, cleaner fish are being used to control sea lice. These fish, such as Wrasse and Lumpfish, feed on sea lice and are placed into salmon pens to eat the lice directly off the salmon
        • Non-medicinal treatments - recently, there have been a number of new technologies developed to control sea lice. These include physical cleaners, which brush the lice off the salmon*; the Hydrolicer, which uses jets of water to remove the lice from the surface of the salmon; and the Thermolicer which uses temp control to remove the lice
        • Freshwater treatments - Freshwater treatments involve bathing salmon in freshwater in the pen or in a wellboat.
        • It is done primarily to treat Amoebic Gill Disease (AGD). However, as sea lice do not survive in freshwater, any lice on the fish being treated for AGD using freshwater will die.

*we’re not currently aware of any members using the brush method.

What is the RSPCA/RSPCA Assured doing to address the problem of sea lice?

        • According to the Scottish Salmon Producers Organisation (SSPO) the number of sea lice affecting farmed salmon is at its lowest level in seven years (2020)
        • However, unfortunately, there is currently no easy answer to solving this problem.  Fish - whether farmed or wild - can suffer from sea lice in the same way that other farm animals and pets can suffer from parasites, such as mites and fleas, and need regular treatment
        • But it’s vitally important that all measures are taken to help reduce the risk of sea lice infestations
        • There is legislation in place that covers the management of sea lice - such as the Aquaculture and Fisheries (Scotland) Act 2007 - which all RSPCA Assured members must follow
        • The Act allows Marine Scotland Fish Health Inspectors to inspect sea lice records and assess the measures which are in place to prevent, control and reduce the numbers of parasites on farms. For example, adherence to the concept of Area Management Agreements and the synchronisation of treatments within these areas.
        • If they are unhappy with any of the measures in place they have the power to insist upon enhanced inspections, issue advice, or implement enforcement action
        • In addition to complying with legislation, we require all RSPCA Assured salmon members to: 
        • Follow the National Treatment Strategy for the control of sea lice on Scottish Salmon Farms.  This is a robust framework for both counting sea lice and identifying when treatment interventions should take place. 
        • These provisions are contained in the Code of Good Practice for Scottish Finfish Aquaculture 
        • Draw up sea lice prevention and treatment programmes with their vet, which must be detailed in their Veterinary Health and Welfare Plan
        • Practise good husbandry, including fallowing, removal of dead and sick fish, and net cleaning.
        • The RSPCA also published standards, in January 2018, relating to using wrasse and lumpsuckers – known as ‘cleaner fish’ - to help control lice on salmon.  These fish live with the salmon and eat the lice off them 
        • But we want to go even further and are continually looking at new ways to help better manage the challenge of sea lice and improve the welfare of salmon.
        • We are pleased to be part of a new working group for a project which will examine the effects of thermal delicing on fish health and welfare. The aim of the project - funded by SAIC (Scottish Aquaculture Innovation Centre) - is to further develop best practices for managing sea lice, whilst ensuring salmon welfare

What is the RSPCA’s view on the use of mechanical sea lice removal methods?

      • The RSPCA is examining and assessing mechanical sea lice removal methods to better understand the impact of these lice removal technologies on fish welfare
      • Technology in this area has been developing rapidly. Results from one company suggest that both the hydrolicer and the thermolicer are effective in removing adult lice in a way that appears to have minimal negative impact on the welfare of the fish, and with very low levels of mortality (0.03-0.12% for the thermolicer and 0.05-0.15% for the hydrolicer). The fish are also reported to return to normal swimming and feeding behaviour soon after the treatment, which suggests that the treatment did not negatively impact upon their welfare
      • At present these mechanical treatments are often brought in where more conventional medicinal treatments have proved to be unsuccessful, and where the alternative would be to leave the fish untreated which, in welfare terms, would be unacceptable as well as unlawful  
      • We are part of a new working group for a project examining the effects of thermal delicing on fish health and welfare. The aim of the project - funded by SAIC (Scottish Aquaculture Innovation Centre) - is to further develop best practices for managing sea lice, whilst ensuring salmon welfare
      • Sea lice are naturally occurring parasites - found on both wild and farmed fish - which feed on the salmon by attaching themselves to their skin and can cause a significant level of suffering if untreated
      • It’s not an easy issue to address but currently, in the absence of a concrete solution to eradicate lice, RSPCA Assured salmon farms can use mechanical lice removal methods as long as the process is carried out responsibly. The welfare of the fish must be a priority at all times and a full risk assessment must be carried out beforehand. The results of the treatment process, and any remedial actions required relating to the process to ensure the welfare of the fish, must be recorded.
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