Le risque d’introduction d'organismes vivants par le commerce d'aquariums, de jardins d'eau et de fruits de mer au Canada

Abstract

The aquarium, water garden, and live seafood trades are major pathways for the introduction of aquatic species into Canada. If released, some imported species may become invasive, with negative consequences for Canadian ecosystems. This research document describes the movement of live aquatic (freshwater, brackish, and marine) organisms including fishes, invertebrates, and plants in trade into and within Canada, identifies aquatic species previously or presently in trade, describes end user participation and the release of aquatic organisms to the wild, develops spatially explicit estimates of propagule pressure, and identifies possible critical control points. A total of 4,296,188 aquarium organisms, representing 844 taxa, were imported into Canada from 40 source countries during a four-month period in 2018. The top three ports of entry, by trade volume, were Windsor, ON; Mirabel, QC; and, Calgary, AB. Imported aquarium organisms were distributed within Canada via major distribution hubs in Innisfil, ON; LaSalle, QC; and, Calgary, AB. Aquarium retailers tended to aggregate around major urban centers. A baseline scenario assuming a 10.6% participation rate and a 3.9% release rate estimated that 57,799 households released 347,650 aquarium organisms per year. During the same four-month timeframe, 3,758,224 water garden organisms, representing 199 taxa, were imported into Canada from 19 source countries. Major ports of entry and distribution hubs for water garden organisms were the same as the aquarium pathway. Water garden retailers were also found around major cities. An estimated 50,769 households released 305,367 water garden organisms per year, based on an assumed 9.2% participation rate and 3.9% release rate. About 82,434,924 live seafood organisms, representing 84 taxa, were imported into Canada from 20 source countries during the same four-month period. Major ports of entry for live seafood organisms included Ottawa, ON; Richmond, BC; St-Stephen, NB; and, Toronto, ON. Montebello, QC; Chilliwack, BC; and, Cap-Pelé, NB were major distribution hubs for live seafood organisms. Similar to the other pathways, live seafood retailers clustered around major cities. An estimated 47,964 users released 288,502 live seafood organisms per year, based on an assumed 3.5% participation rate and 3.9% release rate. Critical control points that allow the greatest volume of organisms in trade to be encountered were identified. For all three pathways, these included the major ports of entry, key distribution hubs, and urban centres where aggregations of retailers, end users, and releasers occur. Results of sensitivity analyses suggested that all parameters considered had an equal effect on the propagule pressure estimates for all pathways, though they had a disproportionate effect on the spatial distribution of end users and releasers. Despite uncertainty around model parameters, statistically significant hot spots of introduction risk were identified. Maintaining detailed import records and characterizing the human dimensions of the aquarium, water garden, and live seafood trades would reduce uncertainty and refine spatially explicit estimates of propagule pressure associated with each pathway.