Research Document 2025/011

Mitigation Measures to Reduce the Risk of Introduction and Spread of Aquatic Invasive Species through Shellfish and Macroalgal Movements

By Massé-Beaulne, V., Simard, N., Bernier, R.Y., Pearce, C.M. and Therriault, T.W.

Abstract

Aquatic Invasive Species (AIS) that are introduced or spread to ecosystems beyond their natural range can threaten Canada’s biodiversity, economy, and society. Shellfish and macroalgal movements are considered to be an important vector for the introduction and spread of AIS in marine ecosystems. To date, a comprehensive evaluation of the effectiveness of treatments that could be used in Canada to kill or remove marine AIS from shellfish and macroalgae being moved and their impacts on those species has not been conducted. Thus, a wide variety of treatments are currently in use without national guidance or consistency. A literature review was undertaken to document the effectiveness of existing treatments to kill/remove AIS and their impacts on moved shellfish and macroalgal species. Effective treatments for AIS from different taxonomic groups (tunicates, bivalves, gastropods, crustaceans, sea stars, macroalgae, polychaetes, bryozoans, sponges, hydrozoans) were evaluated and included physical (pressure washing, air drying, freshwater, heat) and chemical (chlorine-based compounds, acetic acid, citric acid, brine, hydrated lime, Virkon®) sprays/immersions or combinations of these. Treatment impacts on moved species (mussels, oysters, scallops, macroalgae) were also evaluated. Numerous physical and chemical treatments were identified as being effective at killing or removing various AIS and several treatment options were also identified that have no/low impacts on moved shellfish species. Very little information was found for cultured macroalgae transfers. Although a few treatment options were applicable to a large number of AIS, no single treatment was found to be applicable to all AIS while maintaining shellfish survival. Given the context-dependency of treatment options, additional research is needed to develop national standards to mitigate AIS movements associated with shellfish and macroalgal movements in Canada.

Research Document 2025/011 (PDF, 1,843 KB)

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