RESEARCH - Research Summary

Environmental Integrity Theme

Research Summary

Sea lice infection has been regarded as a major factor limiting the production potential of salmon and sea trout stocks. Sea lice infection can result in changes in behaviour and physiology of Atlantic species such as sea trout, Arctic char, and Atlantic salmon. However, relatively little work has been carried out to ascertain the effects of sea lice on species natural to the Pacific coast of Canada.

In addition, as First Nations live in areas that may be optimal for fish farming but also depend on and value marine resources in these areas, it is important that First Nations are included in the management and assessment of the effects of fish farming. Many First Nations will not allow the expansion of fish farming in their territories without first quantifying the risks of sea lice transfer from farmed to wild salmon.

The main goal of this project is to provide a tool that will predict the risk of sea lice infestation to wild fish stocks from potential farming activity. The first step is to determine the risk that various sea lice infestation levels represent to the health of wild salmonids (smolts and adults). This will be achieved by pursuing three primary research objectives.

1. Determining the impact of sea lice infection levels on the swimming and reproductive ability of four Pacific salmonid species native to British Columbia: Laboratory research indicates that sea lice infected Coho smolts show similar stress and physiological responses as those reported for Atlantic salmon, from part of a previous AquaNet project. Additional species to be tested include Chinook, Pink salmon and Steelhead trout;
   
   
2. Effect and source of sea lice on wild migrating fish stocks: Complimentary studies carried out in the field are providing information on natural sea lice infestation levels and migration paths. The stable isotope ratio in sea lice collected from farmed Atlantic salmon and wild Coho stocks were examined. In addition, sea lice collected off commercially reared Atlantic salmon in the Pacific Ocean were compared to the ratio of sea lice from farmed Atlantic salmon in the Atlantic Ocean. The research could successfully differentiate between sea lice sampled from wild salmonids and farmed salmonids, and between sea lice found on the same species of commercially reared salmonids from different areas. The use of stable isotopes will be further explored to assess whether they provide an accurate method for tracing the origin of newly settled infectious stages of sea lice on wild and farmed salmon in the Pacific. In addition, the feasibility of quantifying horizontal sea lice transmission between salmon farms and passing wild salmon, and vice versa will be ascertained; and
   
   
3. Model development and evaluation: The final component of the study is to construct a risk assessment model to assist the farming industry, government, First Nations and other community groups to help assess the potential impact of farming activity to sea lice infestation levels in wild salmonid species. The extensive information gained from this and a previously funded AquaNet project (information on migratory speed and path relative to physical conditions within the fjord, probability of infestation levels at various locations along the migratory path) combined with complimentary information from a European Union project examining the relationship between farming activity and the subsequent risk, will be integrated into an existing model for Atlantic salmon to predict the risk of infestation from sea lice in areas with and without farming activity. The goal is to build locally calibrated models that describe sea lice population dynamics, and to predict the consequences that these parasites have on the stock of wild salmon. The model will significantly advance the industry’s ability to effectively position aquaculture farms, and minimise any potential for contributing to increased sea lice burdens in wild salmonid populations. The model for Atlantic salmon has been completed and the model for Pacific salmon will be completed in 2004/05.
   

Network Investigators

R. Scott McKinley, Faculty of Agricultural Sciences, The University of British Columbia, Vancouver, BC
Bengt Finstad, Norwegian Institute for Nature Research, Trondheim, Norway
John Burka, Dept. of Anatomy and Physiology, Atlantic Veterinary College, University of PEI, Charlottetown, PE

Publications

Bjørn, P.A., Finstad, B. & McKinley, R.S. 2004. Salmon lice on wild and escaped farmed Atlantic salmon in south-western Norway. ICES J. Mar. Sci., submitted.

Butterworth, K.G., Lee, W. and McKinley, R.S. 2004 Carbon and nitrogen stable isotopes: a tool to differentiate between Lepeophtheirus salmonis from different salmonid host species? Aquaculture, 241(1 - 4): 529 - 538.

Thorstad, E.B., Økland, F., Finstad, B., Sivertsgård, R., Bjørn, P.A., and McKinley, R.S. 2004. Migration speeds and orientation of Atlantic salmon and sea trout post-smolts in a Norwegian fjord system. Environmental Biology of Fishes. (In Press)

Wagner, G.N., McKinley, R.S., Bjørn, P.A., and Finstad, B. 2003. Physiological impact of sea lice on swimming performance of Atlantic salmon. Journal of Fish Biology 62: 1000–1009.

Wagner, G.N., and McKinley, R.S. 2004. Anaemia and salmonid swimming performance: the potential effects of sub-lethal sea lice infection. Journal of Fish Biology 64: 1–12.

Wagner, G.N., McKinley, R.S., Bjorn, P.A. and Finstad, B. 2004 Short-term freshwater exposure benefits sea lice-infested Atlantic salmon. J. of Fish Biology (2004) 64, 1593-1604.