Science Advisory Report  2010/085

Science Advice from a Risk Assessment of Smallmouth Bass (Micropterus dolomieu) in British Columbia

Summary

• Smallmouth Bass is native to the Mississippi River and and Great Lakes basins of eastern of North America and was first introduced to British Columbia in 1901 through authorized stocking to provide improved angling opportunities at a few locations. Recent changes in attitude towards introduced species and the importance native species in ecosystem functioning resulted in the need for an assessment of risk posed by Smallmouth Bass to non-invaded regions.
• A risk assessment was conducted which evaluated risk posed to large and small lakes in British Columbia by Smallmouth Bass. The assessment evaluated all stages of invasion including the probability of arrival, survival and reproduction, spread and widespread establishment. Next the assessment characterized the ecological consequences of widespread establishment then combined likelihood and consequences to determine overall risk.
• Overall risk posed to British Columbia by Smallmouth Bass was determined to be high with a moderate uncertainty. Areas predicted to be most highly impacted are the Vancouver Island, lower mainland, upper Fraser, Thompson and Columbia regions. The Arctic, central coast and north coast regions were less likely to be impacted.
• Risk is considered higher in small lakes compared to larger lakes although individual waterbodies within each region will vary in potential risk. In order to determine the risk posed to a particular waterbody, a risk assessment specific to that waterbody needs to be undertaken.
• Smallmouth Bass has specific habitat requirements that may limit establishment and spread.
• Area of highest potential impact is through predation on native minnow and other soft-rayed species.
• It is very difficult to eliminate a species from a system once established. Proactive measures are needed if spread is deemed undesirable.

This Science Advisory Report is from the Fisheries and Oceans Canada, Canadian Science Advisory Secretariat, regional advisory meeting of March 4-6, 2008 on Risk assessment of spiny-rayed fishes (six species). Additional publications from this process will be posted as they become available on the DFO Science Advisory Schedule.

Complete document (PDF, 308 KB)

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