Science Advisory Report 2017/025

National Risk Assessment of Recreational Boating as a Vector for Aquatic Invasive Species

Summary

• This science advisory report is intended to provide advice on recreational boating as a vector for aquatic nonindigenous species (NIS) in Canada. This work dealt with three aspects of this vector (marine, freshwater – Great Lakes Basin, and freshwater overland movement) separately, and for the first time, assessed the risk of recreational boating in terms of introduction and secondary spread of NIS at the national level.
• Primary introductions and secondary spread of known, high impact NIS via recreational boating are possible in Canadian waters.
• Both the freshwater and marine portions of this risk assessment work demonstrate the large magnitude of recreational boating activity in their respective environments. In the marine environment there are an estimated 4.02 M trips per year on the east and west coasts. In the freshwater environment there are an estimated 11.88 M yearly recreational boating events in the Great Lakes Basin (GLB), of which an estimated 3.8 M originate from Canadian recreational access sites. A conservative estimate for the magnitude of inland freshwater boating trips outside of the GLB is 24.7 M per year. This enables rare, per boat events with high consequence to occur.
• High connectivity exists within and among all marine ecoregions, as well as within the waters of the GLB. Nonindigenous species-infested recreational boats from highly connected marinas are very likely to transport NIS to other marinas.
• Natural and anthropogenic barriers exist in both freshwater (i.e. watersheds) and marine (i.e. ecoregions) environments, but recreational boats breach these barriers in both environments and facilitate the movement of NIS within and across these boundaries in both systems. For example, when an invasive species is introduced to the GLB, modelling indicates that on-water boating activity can increase the rate of spread of species to new locations compared to natural dispersal.
• In both marine and freshwater environments, trips that cross physical or ecological barriers, regardless of distance travelled, pose a greater risk than trips that do not cross barriers. In both marine and freshwater environments, long distance spread of NIS via the recreational boating vector is possible. Both environments have a higher frequency of shorter trips than longer trips.
• The riskiest boats are a small subset of all recreational boats in both marine and freshwater environments. Factors identified that influenced boat infestation status included maintenance, voyage history, and boat type. Boats from areas with greater NIS loads that travel extensively and have poor maintenance or extended in-water periods are of greatest risk. Final Ecoregion Invasion Risk scores were greater for the Pacific region than the Atlantic region. These regional differences are largely influenced by seasonality of boating activities (time in water, maintenance, boating activity) and the sheer number of boats.
• An important next step will involve comparing the recreational boating vector to other vectors of NIS introduction and spread.

This Science Advisory Report is from the December 8-11, 2015 National Risk Assessment of Recreational Boating as a Vector for Aquatic Invasive Species. Additional publications from this meeting will be posted on the Fisheries and Oceans Canada (DFO) Science Advisory Schedule as they become available.

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