Invasive Spiny-Ray Fish Eradication Program, Thompson Drainage, British Columbia

Invasive species have been identified as the second greatest threat to biodiversity worldwide (IUCN – World Conservation Union).  In the Thompson drainage of interior BC, the last decade has seen the illegal introduction of invasive spiny-ray fish species into nine small lakes.  The Thompson drainage is the last major drainage in southern BC not infested with spiny-ray species.  It is also home to some of the most productive salmon runs in the province. Including the world famous Adams River sockeye run as well as the endangered COSEWIC listed Interior Fraser Coho.  These nine small lakes are headwater systems, of which five are directly connected to the main Thompson/Shuswap drainage. The presence of these invasive populations threaten not only the biodiversity and local fisheries values of the lakes they are found in, but also the ecological and socioeconomic values of the extensive downstream watersheds.

The introduction of invasive fish species has collapsed the trout populations of all nine lakes affected due to competition and predation impacts. Sampling indicates that these fish have altered the small lake ecosystems beyond the fish community, resulting in a loss of invertebrate, amphibian and bird populations dependent on the aquatic ecosystem.

The Ministry of Natural Resource Operations has collaborated with Fisheries and Oceans Canada, NGOs and First Nations on a multifaceted approach to address the presence of these invasive fish populations.  The plan involves activities including education and awareness, early detection sampling, enforcement and restoration of lakes already infested.  

As part of that program the Fish and Wildlife branch has embarked on a five year rotenone eradication campaign successfully eradicating spiny-ray fish from all nine of the lakes known to contain established populations.  These were the first rotenone treatments completed in BC in the last 20 years.  One of the major hurdles that needed to be jumped was the process to acquire emergency pesticide permits for CFT Legumine and Powdered Rotenone both of which are not registered in Canada permanently.

Five of the rehabilitated lakes have been restocked with catchable sized rainbow trout, the remaining four lakes are scheduled to be stocked in the spring of 2011.  Reports from anglers have confirmed that quality trout fisheries have been restored to these important water bodies.  All nine of the lakes will be reopened to angling by the spring of 2011.  No spiny-ray species have been found post treatment in any of the lakes.