Written by: Lindsay Bagg, Victor Del Dotto, Joe Atkinson, Brianna Grieves, Trevor Vanderkooy.
Distribution: Both the northern pike, Esox lucius and smallmouth bass, Micropterus dolomieu are quite widely distributed both globally and within Canada. Currently the ‘distribution of northern pike is circumpolar in North America and Eurasia, the widest of all species in the genus’ (Harvey, 2009). Similarly, the smallmouth bass can be found throughout Africa, Europe, Russia, and across North America (Brown et al. 2009). Figure 1 illustrates the distribution of northern pike within the province of Ontario while Figure 2 illustrates the distribution of smallmouth bass within the province of Ontario
Habitat: Though northern pike and smallmouth bass occupy a very similar range they do differ slightly in habitat requirements. Northern pike prefer mesotrophic to borderline eutrophic lakes with shallow, moderately productive, vegetated waters that are less than 4 metres deep. Northern pike are often found near the shore zone and in areas with an abundance of aquatic plants as they are critical for the fish in each stage of life (Harvey, 2009). Smallmouth bass on the other hand prefer mesotrophic lakes that are clean and clear, an average of 9 metres deep with more shallow, rocky shoals. Smallmouth bass are often found in the area of littoral drop off. Unlike the northern pike, smallmouth bass are rarely associated with abundant aquatic vegetation. Smallmouth bass prefer cover such as docks, submerged logs and over hanging shore vegetation (Brown et al. 2009). Though both species are most commonly found in lakes both have occasionally been known to inhabit rivers. Both species also seek out more shallow waters with cover in the form of aquatic vegetation for northern pike and fallen trees, and boulders for smallmouth bass as spawning habitat.
Potential for Infestation: Northern pike and smallmouth bass exhibit the typical reproductive strategy of r-strategists. Short gestation periods, numerous offspring, and relatively short lifespans means that r-selected species thrive in disturbed habitats. Key elements of northern pike and smallmouth bass biology that support their classification as r-strategists are summarized in Table 1.
Table 1: Summary of the reproductive characteristics of the northern pike, Esox Lucius and smallmouth bass, Micropterus dolomieu. Note that both species align best with the reproductive characteristics of r-strategists.
|Characteristic||r-strategist||K-strategist||Northern Pike||Smallmouth Bass|
|Mortality||Variable and unpredictable||More constant and predictable||Early life mortality||Early life mortality|
|Clutch Size||Large||Small||32 000 per female – large||14 000 per female – large|
|Parental Investment/Care||Very little if any||Required||Very little if any||Male responsibility for approx. 3 weeks – little|
|Frequency of Reproduction||Once to multiple times over short time period||Multiple times but over a prolonged period||Multiple times but over a prolonged period||Multiple times but over a prolonged period|
|Additional Factors||Most reproductively mature individuals reproduce successfully||Few reproductively mature individuals or only some reproduce successfully||Fecundity is highly variable, depending not only on size of the female, but also on temperature, food availability, social interactions and density|
Survivorship: Both northern pike and smallmouth bass lay thousands eggs each year, many of which may not survive or reach sexual maturity, this designates them as a species with a Type III survivorship curve. The success and survivorship of individuals depends heavily on the environment they find themselves in. Since relatively little parental care is invested in each individual, producing a large number of offspring is important to increase the potential number of survivors.
Dispersal and Vectors:
Northern pike and smallmouth bass are both known to participate in seasonal spawning migrations. Both species will travel up to hundreds of kilometres to tributary streams or rivers to spawn. Outside of this, dispersal is often at the hands of humans. Northern pike and smallmouth bass are often introduced outside of their native range by humans, very often illegally.
Special Considerations: Both northern pike and smallmouth bass can have a dramatic effect on fish community structure and behaviour of other fish species upon introduction to a new ecosystem. Both top predators, once they are established in a new ecosystem both species will rapidly dominate. Northern pike in particular are an opportunistic feeder and will compete with existing predators for food and habitat (Harvey, 2009). There is concern that both northern pike and smallmouth bass prey on salmonids though the ultimate effect on salmonid populations is not clear.
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Casselman, J. M., & Lewis, C. A. (1996). Habitat requirements of northern pike (Esox lucius). Canadian Journal of Fisheries and Aquatic Sciences, 53(S1), 161-174.
Harvey, B. 2009. A biological synopsis of northern pike (Esox lucius). Can. Manuscr. Rep. Fish. Aquat. Sci. 2885: v + 31 p.
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Ontario Fish Species. (n.d.). Retrieved January 27, 2017, from http://www.ontariofishspecies.com/index.html
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