Written By: Joe Atkinson, Lindsay Bagg, Victor Del Dotto, Brianna Grieves, Trevor Vanderkooy
Northern Pike (Esox lucius) and Smallmouth Bass (Micropterus dolomieu) have a long history of being a very popular game fish with anglers. Recreational angling is undoubtedly the number one reason for the introduction of northern pike and smallmouth bass outside their native range. One of the earliest documented introductions of northern pike occurred in Ireland during the 16th century (Harvey, 2009). Similarly, with Smallmouth bass, the species was introduced into several locations across Canada and the United States. They were first introduced into the eastern United States in the late 1800’s and in California in 1874. (Brown, et al. 2009). In Canada, they were introduced by individuals acting by their own volition, into Lake Winnipeg in Manitoba during the early 1900’s followed by Saskatchewan and Alberta as well as in British Columbia where they now reside in the southern Okanagan lakes, Vancouver Island and in the Kootenays (Brown, et al. 2009). Legally they were introduced into Nova Scotia and New Brunswick between 1942 and 1953 (Brown, et al. 2009).
This practice of stocking northern pike and smallmouth bass for recreational fishing has continued to the 21st century and is increasing in popularity. Especially regarding smallmouth bass which is prized as one the most popular sport fish in North America. Large recreational fisheries host tournaments with large prizes offered. In British Columbia alone, the freshwater sport fishery attracts over 400,000 licensed anglers and contributes $233 million to the BC economy and creates 8900 jobs (Harvey, 2009).
When considering eradication methods for Northern pike and smallmouth bass its important to note that both species have vastly different behaviours and tendencies towards particular dispositions. Northern pike for instance is a r-strategist, which quickly spawns and provides no parental care to its young and the fingerlings grow quickly and begin to devour whatever they can. Comparatively, Smallmouth bass are a k-strategist which provides dutiful attention to its young and are capable of producing many offspring because of this.
When Northern pike are introduced into a new environment, they quickly become the dominant predators with no sources of predation on the species besides humans (Craig, 2008). This can be detrimental towards other species such as the Atlantic salmon. If northern pike are introduced into a river where Atlantic salmon spawn, they can quickly decimate a population of young fry (Harvey, 2009). Smallmouth bass are also top predators which pose a threat to both native fish as well as macroinvertebrate diversity as juveniles (Brown, et al. 2009). The introduction of smallmouth bass into areas where they aren’t native caused a shift in prey community structure which indirectly changed the flora and fauna of the system and behaviour of other fish species. (Brown, et al. 2009). In Ontario, smallmouth bass introductions into non-native habitat reduced abundance, altered habitat use and extirpated several minnow and dace species (Brown, et al. 2009).
Critical Assessment of Management Options
Northern pike and smallmouth bass have both successfully established into environments where they have been introduced. This success has caused impacts on other key species such as salmon in the case of both smallmouth bass and northern pike (Carey, et al. 2011). Three primary options are considered for both species. These options are; do nothing, extirpate through use of piscicide and reduce through increased angling.
Firstly, while doing nothing is certainly option for both northern pike and smallmouth bass it is a highly ill advised decision to make, especially in the case of northern pike. As previously discussed, northern pike are an extremely gluttonous species that will consume all available prey and then move onto cannibalism when available resources become short. Similarly, smallmouth bass will also extirpate other species such as minnows, dace and salmon populations among others. (Carey, et al. 2011). If the goal of managing both of these species is to protect other native species, then doing nothing should not be an option.
Extirpation through piscicides is an option. Northern pike have been successfully eliminated in certain Alaska lakes through the use of a naturally occurring ketone; rotenone (Dunker, et al. 2016). Rotenone is an effective agent to be used as a piscicide as well as pesticide in organic farming. This is due to rotenone’s low to moderate mobility in soil and sediment, low potential for bioaccumulating in aquatic organisms and is unstable in the natural environment. With a hydrolysis and photolysis half-lives measured in days and hours (Finlayson, et al. 2014). In a study conducted in Oregon, USA where rotenone was used to effectively eradicate tui chub, rotenone concentrations were found to have decreased by 75% after just 2 days (Finlayson, et al. 2014). Despite all this, the use of rotenone in an aquatic environment poses a significant challenge due to its effects on non-target organisms such as amphibians and macroinvertebrates (Dalu, et al. 2015). Effects on other non-target species could range from 100% mortality to no effect but while it is known to affect numerous aquatic species, there are few studies that have assessed the total impacts and its ramifications on many species remains unknown (Dalu, et al. 2015).
Finally, the option of reducing through increased angling is a possible management option. With regards to northern pike this is possibly the best option. Northern pike are easily hooked and generally bite throughout the entire day. (Margenau, et al. 2008). According to the Department of Natural Resources of Michigan, a lake stocked with 68 adult northern pike caught 31% (22 pike) within 2 hours of angling per acre in one day (Williams, Jacobs. 1971). While this method won’t entirely guarantee eradication of the species it does provide a good potential source tourism and income from anglers. Northern pike and smallmouth bass are two of the most popular sport fish and complete eradication of the species in certain areas could cause a public outcry. Top this with the fact that the reason these species have spread so far is because of illegal introductions from anglers, guaranteeing that they will not be re-introduced after a total extirpation is hard if not impossible to prevent.
Figure 3: This infographic displays the individual benefits and factors for each of the three management strategies discussed. Least effective strategy would be to do nothing. Extirpation is the most effective method but piscicide will have unknown effects on non-target species. Increasing angling and encouraging catch and keep can reduce populations but other species will still be effected.
Brown, T.G., Runciman B., Pollard, S., Grant, A.D.A., Bradford, M.J. (2009) Biological synopsis of smallmouth bass (Micropterus dolomieu). Canadian Manuscript Report of Fisheries and Aquatic Sciences 2887: v + 50 p. Retrieved from http://www.dfo mpo.gc.ca/Library/337846.pdf
Carey, M. P., Sanderson, B. L., Friesen, T. A., Barnas, K. A., & Olden, J. D. (2011). Smallmouth Bass in the Pacific Northwest: A Threat to Native Species; a Benefit for Anglers. Reviews In Fisheries Science, 19(3), 305-315. doi:10.1080/10641262.2011.598584 retrieved from http://ra.ocls.ca/ra/login.aspx inst=sandford&url=http://search.ebscohost.com.eztest. cls.ca/l gin.aspx?direct=true&db=eih&AN=78279541&site=eds-live&scope=site
Dalu, T., Wasserman, R. J., Jordaan, M., Froneman, W. P., & Weyl, O. F. (2015). An Assessment of the Effect of Rotenone on Selected Non-Target Aquatic Fauna. Plos ONE, 10(10), 1-13. doi:10.1371/journal.pone.0142140
Dunker, K. J., Sepulveda, A. J., Massengill, R. L., Olsen, J. B., Russ, O. L., Wenburg, J. K., & Antonovich, A. (2016). Potential of Environmental DNA to Evaluate Northern Pike (Esox lucius) Eradication Efforts: An Experimental Test and Case Study. Plos ONE, 11(9), 1-21. doi:10.1371/journal.pone.0162277
Finlayson, B. J., Eilers, J. M., & Huchko, H. A. (2014). Fate and behavior of rotenone in Diamond Lake, Oregon, USA following invasive tui chub eradication. Environmental Toxicology & Chemistry, 33(7), 1650-1655. doi:10.1002/etc.2608
Harvey, B. (2009) A biological Synopsis of Northern Pike (Esox Lucius). Canadian Manuscript Report of Fisheries and Aquatic Sciences 2885: v + 31 p. Retrieved from http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.482.2048&rep=rep1&type pdf
Margenau, T., AveLallemant, S., Giehtbrock, D., & Schram, S. (2008). Ecology and management of northern pike in Wisconsin. Hydrobiologia, 601(1), 111-123. doi:10.1007/s10750-0079258-z Retrieved from http://ra.ocls.ca/ra/login.aspx?inst=sandford&url=http://search.ebscohost.com.eztest. cls.ca/login.aspx?direct=true&db=aph&AN=29546883&site=eds-live&scope=site