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Research Document - 2014/002

A review of potential environmental risks associated with the use of pesticides to treat Atlantic salmon against infestations of sea lice in Canada

By L.E. Burridge and J.L. Van Geest


This research document was one of three documents prepared as part of a DFO Canadian Science Advisory Secretariat (CSAS) process held 13-15 March 2013, in Saint John, NB. The purpose of the process was to evaluate the current knowledge relating to the exposure and biological effects of pesticide bath treatments on non-target organisms in order to provide peer-reviewed science advice to DFO's Aquaculture Management Directorate and identify knowledge gaps and research needs. This advice is required to inform the development of regulations and policies under Section 36 of the Fisheries Act related to aquaculture pest and pathogen management and will also support Health Canada's environmental risk assessments related to the emergency registrations of pesticides. This paper reviewed the biological effects of four pesticide formulations, three that have been available via emergency registration: Salmosan® (active ingredient: azamethiphos), AlphaMax® (active ingredient: deltamethrin), and Paramove 50® (active ingredient: hydrogen peroxide) and one which is used in other jurisdictions and interest had been expressed in using the product in Canada, Excis® (active ingredient cypermethrin). Of these products only Salmosan® and Paramove 50® are currently being used as bath treatments to control sea lice in farmed salmon in Canada. In general, the effects on non-target organisms varied with the formulation being applied with lobster being the most sensitive species tested. The degree of toxicity was therapeutant specific with Paramove 50® being the least toxic of the three formulations tested, while AlphaMax® was the most toxic. Sublethal effects of repeated or long-term exposure of lobsters to Salmosan® are presented showing that repeated exposure may affect reproduction and shipping quality may be affected by long-term exposure. Data on the effects of these pesticides on Pacific non-target species is rare.

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