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Assessment of the environmental impact of the treatment of sea lice with the pesticide SLICE® at aquaculture facilities in British Columbia

Pacific Regional Science Advisory Process

October 18 – 19, 2011
Sidney, B.C.

Chairperson: Andrew Ross


Sea lice are naturally occurring parasites found on salmon and other fish in Canadian and international waters. Farmed salmon are subject to infestation with sea lice, and there exists the potential for transfer of lice between farmed salmon and wild fish populations. Fisheries and Oceans Canada (DFO) recognizes the possibility that a heavy sea lice burden can affect the survivability of very young salmon. Consequently sea lice levels are carefully controlled on British Columbia’s salmon farms, thereby reducing the risk of infecting fish that live outside the farm. Current sea lice management strategies include fallowing (modifying production cycles to minimize farmed fish presence during key periods), harvest and preventative treatment of farms with anti-parasitic chemotherapeutants. The main chemical used to treat sea lice at farms sites in British Columbia is SLICE®, in which the active ingredient is Emamectin Benzoate (EB). The application of such treatments to manage sea lice levels at marine cage finfish sites can lead to the release of these chemicals into the broader environment through a variety of pathways (e.g. dissolution, particle transport and sedimentation). This presents the potential for chemical residence in the water column, accumulation in benthic ecosystems and exposure of non-target organisms. In recent years, DFO Science Branch has been engaged in research to investigate the fate and environmental concentrations of EB following the use of SLICE® at a number of finfish aquaculture sites in B.C. This research has been supported in part by the Program for Aquaculture Regulatory Research (PARR), an internal DFO program that funds research aimed at increasing the science knowledge base used to inform ecosystem-based environmental regulation and decision-making with regard to the aquaculture sector (Program for Aquaculture Regulatory Research (PARR)). DFO Fisheries and Aquaculture Management (FAM) Division has requested that a Regional Advisory Process be undertaken to report on the results of current DFO research on the fate of EB following SLICE® applications at marine cage finfish sites. A Science review is sought to corroborate the above-mentioned pathways, and Science Advice requested on the potential distribution and environmental interactions of EB in the vicinity of B.C. finfish farms.


The main objective of this Regional Advisory Meeting (RAP) will be to answer the general Question:
Does the current use of SLICE® in B.C. finfish farms result in the exposure of non-target organisms to levels of emamectin benzoate (EB) that could result in biological effects? The following working paper will be reviewed and provide the basis for discussion and advice on the specific questions outlined below.

Ikonomou, M.G. Environmental Fate and Potential Biological Effects of the Anti-Parasitic Chemo-therapeutant Emamectin Benzoate (active ingredient of SLICE®). CSAP Working Paper 2011/P14.

Specific questions to be addressed:
  1. Is emamectin benzoate (EB) detectable in water and sediment surrounding Finfish Farms and at distant Reference Sites in B.C. coastal waters?
  2. If so, what is the spatial and temporal distribution of EB in the vicinity of Finfish Farms following the application of SLICE®, and how does this compare with the Reference Sites?
  3. How does the EB footprint relate to local conditions (e.g. depositional vs. dispersive sites, pH), and can the distribution and decomposition of EB be effectively modelled?
  4. How do the concentrations of EB measured in water and sediment at Reference Sites and within 300 metres of Finfish Farms compare with those measured in non-target organisms (e.g. shrimp) and with those found, through toxicological studies, to result in biological effects?

The goal of the first day will be to review the findings of a recent study carried out by DFO Science to measure EB concentrations in water and sediment from Reference Sites and Finfish Farms before, during and after the application of SLICE®. Day 1 will also include a brief review of the analytical methodology developed for EB analysis, and of the available information concerning the toxicity of EB to benthic marine organisms. The goal of Day 2 will be to address as many of the aforementioned questions as possible, based on the available information, and to provide advice and recommendations regarding the use of SLICE® to control sea lice at aquaculture facilities in B.C.


Expected outputs include a CSAS Research Document, Science Advisory Report, and Proceedings.


Participants will be invited from DFO (Science, Aquaculture Management, Ecosystem Management), Environment Canada, Health Canada, First Nations, academic and non-government organizations, Aquaculture Pharmaceutical producers, and the Aquaculture Industry, based on the knowledge and expertise to be contributed through this advisory process.


Participation to CSAS peer review meetings is by invitation only.

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