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Panic at the cisco: Predicting the impacts of climate change on cisco distributions in Ontario

Climate change has been driving the movement of native and invasive species into new habitats over the last two decades. Many Ontario fish species currently occur in lakes farther north than they did historically (Alofs et al., 2014). In particular, the distribution of coldwater fish has been a key indicator of how increases in water temperature may impact aquatic ecosystems. Cisco (Coregonus artedii) is an important coldwater forage fish and is a vital prey resource to top predators such as lake trout (Salvelinus namaycush), northern pike (Esox lucius) and walleye (Sander vitreus) (Jacobson et al., 2010). Research by Sharma et al. (2011) and Fang et al. (2012) suggests that cisco populations will be vulnerable to changes in water temperature under climate change. With increasing water temperatures and precipitation events, climate change is predicted to limit the availability of preferred thermal habitat for cisco (Ficke et al., 2007). Therefore, with warmer waters and reduced concentrations of dissolved oxygen, cisco may become extirpated from their current ranges (Ficke et al., 2007; Fang et al., 2012). Research conducted by Miranda Chen, from Dr. Sapna Sharma’s lab at York University , has examined these predicted effects of climate change on cisco distributions in Ontario (Van Zuiden* and Chen* et al. In press).

Miranda is a recent MSc graduate from Dr. Sapna Sharma’s lab at York University, Toronto. In collaboration with Dr. Satyendra Bhavsar from the Ontario Ministry of the Environment and Climate Change (MOECC), Miranda’s research also extends to investigating how sport fish mercury levels may be changing relative to a changing climate. She is now working on her doctorate at the University of Tennessee, Knoxville in Biology Education research.

Using a historical dataset of 9885 Ontario inland lakes surveyed between 1957-1986 (Dodge et al. 1985) and a contemporary dataset of 722 lakes sampled between 2008-2012 (Sandstrom et al., 2010), Miranda identified important environmental characteristics, such as lake morphology, lake chemistry and presence of predators and prey on cisco occurrence in Ontario. Subsequently, she predicted future cisco occurrence across Ontario for the years 2050 and 2070 by incorporating future climate change scenarios from 19 general circulation models and four greenhouse gas scenarios into the best predictive model of cisco occurrence. Using a logistic regression model, she determined that cisco prefer larger, deeper lakes, in cooler regions of Ontario and that warming air temperatures corresponded to a decline of cisco occurrence ranging from 8-37% (x̄ = 20%) by 2050 and 7-47% (x̄ = 26%) by 2070 (Van Zuiden* and Chen* et al. In press; Figure 1).

The loss of cisco populations in Ontario can have major impacts on native freshwater communities, especially on the growth of top predators such as lake trout. Along with the increased distribution of invasive species, such as rainbow smelt, these important forage prey fish may be further at risk to be extirpated in their native habitats (Jacobson et al., 2010; Sharma et al., 2011). Fisheries and conservation managers must examine and integrate these predictive models into their decisions by appropriately triaging which lakes best protect cisco from extirpation and ultimately help to maintain the ecological health of Ontario lakes.

Though the Sharma lab is a quantitative lab, her students are always collaborating with government scientists to gain field experience. Along with other Sharma lab members (affectionately termed “Sharmites”), Miranda was able to spend a summer working with scientists such as Dr. James Rusak, Chris Jones and students from Dr. Shelly Arnott’s (Queen’s University) and Dr. John Gunn’s (Laurentian University) lab, working at the Ontario Ministry of the Environment’s Dorset Environmental Science Center (DESC). There, Sharmites assisted in gillnetting, processing fish samples, assessing water quality, identifying benthic invertebrates, etc.


Alofs, K.M., Jackson, D.A., Lester, N.P. 2014. Ontario freshwater fishes demonstrate differing range-boundary shifts in a warming climate. Divers Distrib. 20: 123-136.

Dodge, D.P., Goodchild, G.A., MacRitchie, I., Tilt, J.C., Waldriff, D.G. 1985. Manual of instructions: aquatic habitat inventory surveys. Ontario Ministry of Natural Resources, Fisheries Branch, Toronto, ON.

Fang, X., Jiang, L., Jacobson, P.C., Stefan, H.G., Alam, S.R., Pereira, D.L. 2012. Identifying cisco refuge lakes in Minnesota under future climate scenarios. T Am Fish Soc. 141: 1608-1621.

Ficke, A.D., Myrick, C.A., Hansen, L.J. 2007. Potential impacts of global climate change on freshwater fisheries. Rev Fish Biol Fisher. 17: 581-613.

Jacobson, P.C., Stefan, H.G., Pereira, D.L. 2010. Coldwater fish oxythermal habitat in Minnesota lakes influence of total phosphorus, July air temperature, and relative depth. Can J Fish Aquat Sci. 67: 2002-2013.

Sandstrom, S., Rawson, M., Lester, N.P. 2010. Manual of instructions for broad-scale fish community monitoring; using large mesh gillnets and small mesh gillnets. Ontario Ministry of Natural Resources, Peterborough, ON.

Sharma, S., Vander, Zanden, M.J., Magnuson, J.J., Lyons, J. 2011. Comparing climate change and species invasions as drivers of coldwater fish population extirpations. PLoS ONE. 6: e22906.

Van Zuiden*, T.M., Chen*, M., Stefanoff, S., Lopez, L., & Sharma, S. 2015. Projected impacts of climate change on three freshwater fishes and potential novel competitive interactions. Divers Distrib. In Press.

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