Mechanical Eradication of Invasive Fish Species Can Be Effective

brrokWhen you think of a national park, you probably have a vision of a place that is mostly pristine and untouched. So when Parks Canada took on the task of trying to eradicate the invasive Brook Trout Salvelinus fontinalis from the Middle and Lower Devon lakes, which form part of the headwaters of the Clearwater River in Banff National Park, they took into consideration the public’s notion of what a national park should be: a protected area, free of chemicals. For more than 70 years, piscicides (e.g., rotenone and antimycin) have been used to eradicate fish species (McClay 2000); however, their use has legal and social implications (Finlayson et al. 2000). In the North American Journal of Fisheries Management, Charlie Pacas and Mark K. Taylor of Parks Canada were able to show how mechanical methods can be an effective method for trout eradication in lotic and lentic environments. In the upper part of Clearwater River, they used electrofishing to target non-native Brook Trout, and in the two Devon lakes, they used gillnetting as well as shoreline electrofishing. Then after the last fish were caught in the lakes and river, they conducted postremoval monitoring using the same methods to confirm their findings. To date, most fish removal projects using only mechanical methods have failed to demonstrate 100% effectiveness, especially projects of this size. The authors credit their success to the simple morphology of the alpine lakes and river (both lacked structure such as vegetation that could prevent fish capture) as well as the intensity of their effort.


Finlayson, B. J., R. A. Schnick, R. L. Cailteux, L. DeMong, W. D. Horton, W. McClay, C. W. Thompson, and G. J. Tichacek. 2000. Rotenone use in fisheries management: administrative and technical guidelines manual. American Fisheries Society, Bethesda, Maryland.

McClay, W. 2000. Rotenone use in North America. Fisheries 25(4):15-21. Pacas, C., and M. K. Taylor. 2015. Nonchemical eradication of an introduced trout from a headwater complex in Banff National Park, Canada. North American Journal of Fisheries Management 35:748–754.

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