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Guidelines on Defining Potential Exposure and Associated Biological Effects from Aquaculture Pest and Pathogen Treatments: Anti-Sea Lice Bath Treatments (Part II)

National Peer Review – National Capital Region

March 13-15, 2013
Saint John, NB

Co-Chairs: Jay Parsons and Ingrid Burgetz

Context

Sea lice are naturally occurring marine ectoparasites that attach to the skin and feed on the mucus, blood and surface tissues of salmon and other species of fish.  Sea lice species occur on both the east and west coast; however, there are differences in sea lice behaviour and parasite-host population dynamics observed between these two environments.  Minor sea lice infestations are generally not harmful, but damage to surface tissues can occur as sea lice abundance on the fish increases.  Heavy sea lice loads have the potential to develop and subsequently affect the fish’s physiology, behaviour and increase the risk of death due to osmotic shock, blood loss or secondary infections.  As such, salmon aquaculture operators require means for controlling sea lice abundance within net pens.

Controlling sea lice abundance on farmed salmon reduces production losses or the risk of increasing infestation levels on surrounding wild salmon and other aquatic resources.  Generally, integrated plans for fish health include measures to control sea lice abundance through husbandry practices (e.g., single year class stocking, and fallowing); the use of non-chemical approaches (e.g., light traps in development, cleaner fish, etc.); and the use of chemotherapeutants (pesticides and drugs).

Chemotherapeutants are administered as either in-feed drugs or pesticides applied in bath treatments in tarped or skirted cages or via wellboats.  In Canada, there are no fully registered bath treatments for sea lice, but some products are available to provincial authorities via emergency registrations.  All applications for pesticide registration to Health Canada’s (HC) Pest Management Regulatory Agency (PMRA) under the Pest Control Product Act undergo a rigorous Environmental Risk Assessment (ERA) to assess risks to the environment and non-target organisms.  PMRA’s ERA uses available research and ERAs conducted by other countries.  In addition, DFO’s Program for Aquaculture Regulatory Research and Aquaculture Innovative Market Access Program, and the Government of New Brunswick have funded research on the toxicity of treatments on non-target organisms and the dynamics of product dispersion to support PMRA’s ERAs.  Since 2010/11, Paramove® 50 (active ingredient: hydrogen peroxide) was the most frequently used bath treatment in New Brunswick and Newfoundland.  Pesticides available under emergency registration are determined by the PMRA to pose acceptable risk to non-target organisms if used according to label directions.  Environment Canada (EC) is responsible for preventing the deposition of deleterious substances in waters frequented by fish (Fisheries Act s. 36(3)).  The definition of ‘deleterious’ requires scientific data to provide a reference to be used by DFO Fisheries and Aquaculture Management, HC, PMRA, and EC.

Regardless of the chemotherapeutant application method, chemical is released into the aquatic environment and then dissipates through various mechanisms such as degradation, binding to organic material, partitioning to sediments, among others, where it can potentially affect other organisms.  The release of any chemotherapeutant into the aquatic environment contravenes s. 36(3) of the Fisheries Act unless the deposits are authorized by regulation.  DFO’s Aquaculture Management Directorate (AMD) is developing regulations, Aquaculture Activities Regulations (AAR) under s 36(3) of the Fisheries Act to manage the use of chemotherapeutants to control fish pathogens and pests affecting farmed finfish and the environment.  The purpose of this peer review process is to provide scientific advice to support the development of regulations and PMRA’s ERA for pesticide registrations.

Objectives

In order to meet the objectives of the proposed AAR, AMD requires peer-reviewed science advice on exposure and biological effects of sea lice bath treatments on non-target organisms to support AAR implementation and policies that protect wild aquatic resources, as well as facilitate PMRA’s review of sea lice pesticides.

A Canadian Science Advisory Secretariat (CSAS) peer review process (Part I) was held November 1-2, 2011 in St. Andrews, NB as the first step of a two-step national peer review process. The objective was to assess current knowledge and research undertaken to date to define potential exposure and biological effects on non-target organisms, focusing on the Bay of Fundy.  Key conclusions from Part I were:

  1. Water plume transport distances vary with ocean currents, tides, and mode of treatment (cage vs wellboat);
  2. American lobster, a commercially important species, was consistently more sensitive to therapeutants than Crangon and Mysid shrimps tested, and;
  3. In lab studies, effects on non-target organisms differed with the pesticide being applied:  Paramove® 50 (active ingredient: hydrogen peroxide) was the least toxic and AlphaMax® (active ingredient: deltamethrin) was the most toxic tested.

The CSAS national peer review process (Part II) will add to the outcomes of Part I but be broader in scope and include other regions of Canada.  Part II will focus on the questions below:

  1. What are the general factors that influence the exposure of non-target organisms to bath treatments (wellboat, skirt, and tarp applications) and how does the relative importance of these factors vary under different salmon-production environments?

    A literature review of the fate and transport dynamics and dispersion, analysis of dispersion and dilution of pesticide treatments, and dispersion model results are required.
  2. What are the known biological effects (lethal, sub-lethal and/or behavioural) of hydrogen peroxide, azamethiphos, cypermethrin, and deltamethrin on key non-target organisms?

    A literature review of toxicological, physiological, and behavioural effects on specific non-target organisms at different levels, treatment frequency and chemical regimes, along with results from the Program for Aquaculture Regulatory Research from 2009-12, are required.
  3. How does pesticide concentration and duration (or persistence) relate to dispersion patterns at known biological effect concentrations over various environmental conditions?  How do these relate to the non-target organisms’ life-cycle and migratory/spawning dynamics?

    This will require modelling of results from (1) and (2) and life-history knowledge from the scientific literature on the non-target species used in research.
  4. Can the dispersion models be applied to other salmon farming areas in Canada and other non-target species?

Expected Publications

Participation

Notice

Participation to CSAS peer review meetings is by invitation only.

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