Epidemiology And Control - Parasite Management and Control

One of the most challenging problems in aquaculture is the treatment of parasites using chemotherapeutants that are both appropriate for use in the aquatic environment and non-toxic to the host or the consumer at efficacious doses.

The most economically important disease problem of marine-farmed salmonids worldwide is caused by the sea lice, Lepeophtheirus salmonis and Caligus spp. These lice are parasitic copepods which cause serious damage and mortality to salmonids in marine cages in e.g. Scotland, Norway, Chile, Ireland and Canada. A long term programme of collaborative research with the pharmaceutical industry and the aquaculture indusry has resulted in a number of useful licensed products for treatment, including the most effectively used SLICE (Schering Plough) which was developed through our work conducted at the Institute's Marine Environment Research Station at Machrihanish, Argyll Novel chemotherapeutants are also being selected and tested against a number of pathogens including the severely pathogenic ciliate protozoan Ichthyophthirius multifiliis commonly known as "white spot", in conjunction with the trout production industry.

Concurrent with the investigation of novel chemotherapeutants, work is being carried out to investigate the possibility of alternative control methods. These include biological control methods and vaccine development. Collaborative work is being carried out to develop a vaccine against salmon lice (Lepeophtheirus salmonis) on farmed salmon.

Epidemiological studies and risk analyses we have conducted have resulted in new advice on changes in management practices designed to keep parasite populations under control. These have been very effective in managing, for example, sea lice and Argulus infections. We have also developed new tools to predict the risk of parasite establishment at different sites across England and Wales. These spatial models integrate a wide range of environmental and biological data and are used to advise government policy on contingency planning and fish health monitoring.

Selected References

  1. Taylor, N.G.H., Sommerville, C. & Wootten, R. (2006) The epidemiology of Argulus spp. (Crustacea: Branchiura) infections in stillwater trout fisheries. Journal of Fish Diseases, 29, 193-200.
  2. Shinn, A.P., Wootten, R., Côté, I. & Sommerville, C. (2003) The efficacy of selected bath and oral chemotherapeutants against Ichthyophthirius multifiliis Fouquet, 1876 (Ciliophora: Ophyroglenidae) infecting rainbow trout (Oncorhynchus mykiss Walbaum). Diseases of Aquatic Organisms, 55, 17-22.
  3. Stone, J., Boyd, S., Sommerville, C. & Rae, G.H. (2002) An evaluation of freshwater bath treatments for the control of sea lice, Lepeophtheirus salmonis (Kroyer), infections in Atlantic Salmon,Salmo salar L. Journal of Fish Diseases, 25, 371-373.
  4. Stone, J., Roy, W.J., Sutherland, I.H., Ferguson, H.W., Sommerville, C. & Endris, R. (2002) Safety and efficacy of emamectin benzoate administered in feed to Atlantic salmon, Salmo salar L., smolts in freshwater, as a preventative treatment against infestations of sea lice, Lepeophtheirus salmonis (Kroyer). Aquaculture, 210, 21-34.
  5. Tucker, C.S., Norman, R., Shinn, A.P., Bron, J.E., Sommerville, C. & Wootten, R. (2002) A single cohort, time delay model of the life cycle of the salmon louse (Lepeophtheirus salmonis) on Atlantic salmon Salmo salar. Fish Pathology, 37, 107-118.
  6. Shinn, A.P., Wootten, R. & Sommerville, C. (2000) Novel chemical control methods Ichthyophthirius multifiliis (Fouquet, 1876) (Ciliophora). Acta Parasitologica, 45 (3), 270.
  7. Stone, J. & McLean A. (2000) Setting up GCP trials in fish (Chapter 8) In: Veterinary Clinical Trials from concept to Completion. Dent N. & Visanji R. (Ed) Interpharm Press, Englewood, USA.
  8. Stone, J., Sutherland, I.H., Sommerville, C., Richards, R.H. & Endris, R.G. (2000) The duration of efficacy following oral treatment with emamectin benzoate against infestations of sea lice, Lepeophtheirus salmonis (Kroyer), in Atlantic salmon Salmo salar (L.) Journal of Fish Diseases, 23, 185-192.
  9. Stone J., Sutherland I.H., Sommerville C., Richards R.H., Varma, K.J. (2000) Commercial trials using emamectin benzoate to control, Lepeophtheirus salmonis (Krøyer) and Caligus elongatus (Nordmann), infestations in Atlantic salmon, Salmo salar L. Diseases of Aquatic Organisms, 41, 141-149
  10. Stone, J., Sutherland, I.H., Sommerville, C., Richards, R.H., Varma, K.L. (2000) Field trials to evaluate the efficacy of emamectin benzoate in the control of sea lice Lepeophtheirus salmonis (Krøyer) and Caligus elongatus Nordmann, infestations in Atlantic salmon Salmo salar (L.). Aquaculture, 186, 205-219.
  11. Stone, J., Sutherland, J.H., Sommerville, C., Richards, R.H. & Varma, K.J. (1999) The efficacy of emmamectin benzoate as an oral treatment of sea lice, Lepeophtheirus salmonis (Krøyer), infestations in Atlantic salmon, Salmo salar. Journal of Fish Diseases, 22 (4) 261-270
  12. Sommerville, C. (1998) Parasitic Diseases of Fish. In “The Biology of Farmed Fish” (eds Black, K. & Pickering, A.). Sheffield Biological Sciences, Vol. 1 Sheffield Academic Press.
  13. McAndrew, K., Sommerville, C., Wootten, R. & Bron, J.E. (1998) The effects of hydrogen peroxide treatment on different life-cycle stages of the salmon louse Lepeophtheirus salmonis (Krøyer, 1837). Journal of Fish Diseases, 21, 221–228.
  14. Gibson, D.R. & Sommerville, C. (1996) The potential for viral problems related to the use of wrasse (Labridae) in the farming of Atlantic salmon. In: “Wrasse: Biology and use in Aquaculture”. (Eds. Sayer, M.D.J., Treasurer, J.W. & Costello, M.J.), 240–250.
  15. Andrade-Salas, O., Sommerville, C., Wootten, R., Turnbull, T., Melvin, W., Arnezaga, T. & Labus, M. (1993) Immunohistochemical screening and selection of monoclonal antibodies to the salmon louse Lepeophtheirus salmonis (Kroyer, 1837). In: “Pathogens of Wild and Farmed Fish: Sea Lice” Boxshall, G. & Defaye, D. (eds.) Ellis Horwood Ltd., 323-331.
  16. Roth, M., Richards, R.H. & Sommerville, C. (1993) Preliminary studies on the efficacy of two pyrethroid compounds resmethrin and lambdacyhalothrin, for the treatment of sea lice (Lepeophtheirus salmonis) infestations of Atlantic salmon (Salmo salar). In: “Pathogens of Wild and Farmed Fish: Sea Lice”. Boxshall, G. & Defaye, D. (eds.) Ellis Horwood Ltd., 275-289.
  17. Bron, J.E., Sommerville, C., Wootten, R. & Rae, G.H. (1993) Fallowing of marine Atlantic salmon, Salmo salar L., farms as a method for the control of sea lice Lepeophtheirus salmonis (Kroyer, 1837). Journal of Fish Diseases, 16, 487-493.
  18. Bron, J.E., Sommerville, C. & Rae, G.H. (1993). Influence of treatment with dichlorvos on the epidemiology of Lepeophtheirus salmonis (Kroyer, 1837) and Caligus elongatus Nordmann, 1832 on Scottish salmon farms. In: “Pathogens of Wild and Farmed Fish: Sea Lice”. Boxshall, G. & Defaye, D. (eds.) Ellis Horwood Ltd., 263-274.
  19. Roth, M., Richards, R.H. & Sommerville, C. (1993) Current practices in the chemotherapeutic control of sea lice infestations in aquaculture - a review. Journal of Fish Diseases, 16 (1), 1-26.
  20. Roth, M., Richards, R.H. & Sommerville, C. (1993) Current practices in the chemotherapeutic control of sea lice infestations in Aquaculture. A review. Journal of Fish Diseases, 16 (1), 1-27.
  21. Bron, J.E. & Treasurer, J.W. (1992) Sea lice (Caligidae) on wrasse (Labridae) from selected British wild and salmon-farm sources. Journal of the Marine Biological Association of the U.K., 72, 645-650
  22. Jones, M.W., Sommerville, C. & Wootten, R. (1992) Reduced Sensitivity of the salmon louse Lepeophtheirus salmonis to the organophosphate Dichlorvos. Journal of Fish Diseases, 15, 303-310.
  23. Roth, M. & Richards, R.H. (1992) Trials on the efficacy of azamethiphos and its safety to salmon in the control of sea lice. In: “Chemotherapy in Aquaculture: from Theory to Reality.” Micher, C. & Alderman, D.J. (Eds.) Office International des Epizootes, Paris, 212-218.