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Research Document 2022/055

“Clean, Drain, Dry, and Decontaminate” treatments and protocols to prevent the introduction and spread of aquatic invasive species

By Weise, A.M., Simard, N., Massé-Beaulne, V. and Hill, J.M.


Aquatic invasive species (AIS) pose a significant threat to Canadian fresh, estuarine, and marine waters and threaten Canada’s biodiversity, economy, and society. To prevent the introduction and spread of AIS by water-based commercial and recreational activities, many government and non-government organizations encourage owners and operators to voluntarily Clean, Drain, and Dry (CDD) their watercraft, trailers, and equipment. In some cases, an additional Decontamination step may be applied (CDD+D) which has species-specific treatment parameters to achieve AIS mortality and/or removal. To date, a comprehensive evaluation of the effectiveness of CDD+D protocols used in Canada for marine and freshwater AIS has not been conducted. This research document provides a review, by species, of effective decontamination treatments identified in the scientific literature and suggests treatment guidelines aimed to kill the greatest number of target AIS taxa. The effectiveness of recommendations in existing freshwater and marine CDD+D protocols used in AIS management across Canada or abroad were also assessed. Lethal decontamination treatments for AIS of interest from different functional and taxonomic groups (e.g., bivalves, gastropods, zooplankton, macrophytes, macroalgae, crabs, and tunicates) were evaluated and included physical (e.g., hot water spray/immersion, pressure washing, air-drying, and freezing) and chemical (e.g., sodium hypochlorite, acetic acid, quaternary ammonium compounds, salt water, Virkon©, brine, and hydrated lime) sprays/immersions or a combination of these. The scientific literature showed that several decontamination treatments can be lethal for AIS but only if applied for specific exposure times and conditions. Recommendations in government or state protocols mostly echoed the scientific literature and underline that CDD campaigns should continue to be supported across the country. In some cases, when additional decontamination is required, (e.g., a watercraft is at high risk of transporting AIS), temperature, pressure, and/or chemical treatments may need to be adjusted to ensure 100% mortality of a greater number of target AIS. Although numerous species- or environment-specific decontamination treatments were identified as effective at killing or removing AIS, no single decontamination treatment was applicable to all freshwater and marine AIS or to all watercraft and equipment. The results from this study will help develop national CDD+D recommendations and provide advice to Fisheries and Oceans Canada’s regulatory programs and to the Canadian public.

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