Research Document 2017/006

National Risk Assessment of Recreational Boating as a Vector for Marine Non indigenous Species

By Simard, N., Pelletier-Rousseau, M., Clarke Murray, C., McKindsey, C.W., Therriault, T.W., Lacoursière-Roussel, A., Bernier, R., Sephton, D., Drolet, D., Locke, A., Martin, J.L., Drake, D.A.R., and McKenzie, C.H.

Abstract

The National Aquatic Invasive Species Committee (NAISC), a federal-provincial-territorial committee that reports to the Canadian Council of Fisheries and Aquaculture Ministers (CCFAM), submitted a request to DFO Science for science advice related to the potential risk that the recreational boating vector poses to freshwater and marine systems in Canada with respect to the introduction and spread of non‑indigenous species (NIS).

This research document assesses the relative risk posed by recreational boating as a vector for NIS in marine systems on both the East and West coasts of Canada. It includes information on the level of infestation of NIS (Regional NIS Background) in different Canadian and international ecoregions serving as a source for Canadian waters, the probability that boats will be fouled by NIS (Boat Infestation Probability), information on boat movements (Arrival Probability), and environmental similarity between source and receiving ecoregions (Survival Probability). This information was combined with estimates of annual boat traffic to evaluate the relative risk of boating in different Canadian marine ecoregions for the introduction and spread of NIS (Final Ecoregion Invasion Risk).

This assessment provides evidence that primary introduction and secondary spread of NIS may occur via recreational boating in all temperate Canadian marine ecoregions. There was a high degree of connectivity within and between ecoregions on both coasts due to an estimated 4.02 M annual trips per year, while the probability of NIS being transported within and among ecoregions, and of NIS surviving in receiving environments, was relatively high. There was a general trend of greater NIS richness (mainly invasive tunicates) in southern areas relative to northern areas, greater NIS richness on the West coast compared to the East coast, and greater concentrations of NIS richness around high-volume ports/marinas on both coasts. As the majority of transient traffic was intra-ecoregional, the probability of boater-mediated secondary spread of NIS within ecoregions was high. Although, long distance spread of NIS via international and inter-ecoregional recreational boating was less common, it is still a possibility. The Final Ecoregion Invasion Risk score was ‘Highest’ for the Puget Trough/Georgia Basin ecoregion on the Pacific coast and ‘Lowest’ for all other marine ecoregions. This contrast in relative risk was due to seasonal differences in boating activities on each coast and by substantially higher annual traffic in the Georgia Basin relative to other ecoregions in Canada. Special attention should be placed on high risk vessel types in all ecoregions even when they represent a small subset of recreational boats. Specifically, boats with poor maintenance practices, that have spent extended periods in water and are travelling extensively from invaded locations, pose the greatest risk of transporting NIS. Further studies are needed to improve risk estimates for ecoregions where few boats or boaters were surveyed, such as the Labrador Shelf and the Arctic. No measure of impacts has been included in this risk assessment. However, invasive tunicates are well known to be introduced and spread via recreational boat fouling, and for their substantial ecological and economic impacts.

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