Science Advisory Report 2010/086

Science Advice from a Risk Assessment of Walleye (Sander vitreus) in British Columbia

Summary

• Walleye is a freshwater fish native to North America east of the Continental Divide and is only native to northeastern British Columbia.
• Walleye is a piscivorous fish that can have a great impact on prey populations in its native range.
• Walleye has very specific environmental and habitat requirements including the need for the following:

• Large (>400 ha) mesotrophic lakes or turbid rivers or clear deep lakes;
• Clean spawning habitats sheltered from wind or currents;
• Greater than 900°C degree-days in summer;
• An adequate abundance of zooplankton for larvae and forage fishes for juveniles and adults; and,
• Spring temperatures rising above 9°C.

• Walleye migrates to spawning grounds each spring and individuals have been known to travel great distances during non-migratory time periods. This increases the potential for Walleye to move from introduced regions in Washington into southern British Columbia.
• Overall risk posed by Walleye to British Columbia’s aquatic ecosystems was determined to be high with a moderate uncertainty. Areas predicted to be most highly impacted are Lower Mainland, Upper Fraser, Thompson and Columbia regions, but specific waterbodies within each region will vary in potential risk.
• Risk posed to a particular waterbody will need to be determined in a separate, specific risk assessment.
• Once introduced this species is very difficult to eliminate suggesting that proactive measures are needed if its 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, 236 KB)

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