Tom Johnston

Tom Johnston

Research Scientist, Ontario Ministry of Natural Resources and Forestry

Adjunct Professor, Department of Biology

Vale Living with Lakes Centre, Laurentian University

935 Ramsey Lake Road

Sudbury, ON

P3E 2C6

t. 705-671-3828

f. 705-671-3857


Research Interests

I am a fish and fisheries ecologist with the Science and Research Branch of the Ontario Ministry of Natural Resources and Forestry and my research informs and supports fisheries management in Ontario. I am also an Adjunct Professor of Biology at Laurentian University and my research program includes supervision and co-supervision of undergraduate and graduate research projects. My research laboratory is located in the Vale Living with Lakes Centre on the shores of Ramsey Lake.

Specifically, my research examines trophic and reproductive ecologies of fishes, and food web structure and contaminant dynamics in northern aquatic ecosystems. This research is primarily field-based, and covers a wide range of lakes and rivers from across northern Ontario. Current research projects in my lab are examining: i) variation in trophic niche positions and dimensions of fishes along environmental gradients, ii) spatial and temporal patterns of mercury bioaccumulation in aquatic systems, iii) interaction of maternal effects and environmental factors in shaping fish reproductive success, and iv) effects of sampling methodologies on the interpretation of fish community survey data.


Publications (last 6 years)

Sumner, A.W., T.A. Johnston, G.L. Lescord, B.A. Branfireun, and J.M. Gunn. 2019. Mercury bioaccumulation in lacustrine fish populations along a climatic gradient in northern Ontario, Canada.  Ecosystems, In press, doi: 10.1007/s10021-019-00464-9

Mozzon, C.M., G.L. Lescord, P.-L. Savage, and T.A. Johnston. 2019.  The trophic niche of sculpins (Cottus spp.) in forage fish assemblages of boreal lakes. Journal of Fish Biology, In press, doi: 10.1111/jfb.14188

Lescord, G.L., T.A. Johnston,  B.A. Branfireun, and J.M. Gunn. 2019. Mercury bioaccumulation in relation to changing physicochemical and ecological factors across a large and undisturbed boreal watershed.  Canadian Journal of Fisheries and Aquatic Sciences, In press, doi: 10.1139/cjfas-2018-0465.

Johnston, T.A., A.D. Ehrman, G.L. Hamilton, B.K. Nugent, P.A. Cott, and J.M. Gunn.  2019.  Plenty of room at the bottom: niche variation and segregation in large-bodied benthivores of boreal lakes.  Canadian Journal of Fisheries and Aquatic Sciences 76: 1411-1422.

Lescord, G., T.A. Johnston, B. Branfireun, and J.M. Gunn.  2018.  Percentage of methylmercury in the muscle tissue of freshwater fish varies with body size and age and among species. Environmental Toxicology and Chemistry 37: 2682-2691.

Johnston, T.A.  2018. Egg size and lipid content of lake trout, Salvelinus namaycush, in the wild and in captivity. Canadian Journal of Fisheries and Aquatic Sciences 75: 2123-2135.

Lescord, G., E. Emilson, T.A. Johnston, B. Branfireun, and J.M. Gunn. 2018. Optical properties of dissolved organic matter and their relation to mercury concentrations in water and biota across a remote freshwater drainage basin.  Environmental Science and Technology 52: 3344-3353.

Johnston, T.A., N.P. Lester, and B.J. Shuter. 2016. Recruitment, pp. 830-845  In Craig, J.F.  (ed.)  Ecology of Freshwater Fisheries,  John Wiley and Sons,  West Sussex, UK.

Johnston, T.A., M.C. Prévost, L. C. Haslam, and P.A. Addison.  2016.  Life history variation within and among naturalized rainbow trout populations of the Laurentian Great Lakes.  Journal of Great Lakes Research  42:  861-870.

Haring, M., T.A. Johnston, M.D. Wiegand, and T.E. Pitcher.  2016.  Differences in egg quantity and quality among hatchery and wild- origin Chinook salmon (Oncorhynchus tshawytscha).  Canadian Journal of Fisheries and Aquatic Sciences 73: 737-746.

Persaud, A., A. Luek, W. Keller, F.C. Jones, P. Dillon, J.M. Gunn, and T.A. Johnston.  2015.  Trophic dynamics of several fish species in lakes of a climatically sensitive region, the Hudson Bay lowlands.   Polar Biology 38: 651-664.

Stasko, A.D., T.A. Johnston, and J.M. Gunn.  2015.  Effects of water clarity and other environmental factors on trophic niches of two sympatric piscivores.  Freshwater Biology  60: 1459-1474.

Cott, P.A., A. Schein,  B.W. Hanna, T.A. Johnston, D.D. MacDonald, and J.M. Gunn.  2015.  Implications of linear developments on northern fishes.  Environmental Reviews  23: 177-190.

Johnston, T.A., and C.C. Wilson.  2015.  Comparative ecologies of domestic and naturalized rainbow trout in northern Lake Huron (Ontario, Canada).  Ecology of Freshwater Fish  24: 338-354.

Wiegand, M.D., T.A. Johnston, L.R. Porteous, A.J. Ballevona, J.M. Casselman, and W.C. Leggett.  2014.  Comparison of ovum lipid provisioning among lake whitefish, walleye and northern pike co-habiting in Bay of Quinte (Lake Ontario, Canada).  Journal of Great Lakes Research 40:  721-729.

Cott, P.A., A. Hawkins, D. Zeddies, B. Martin, T.A. Johnston,  J. Reist, J.M. Gunn, and D.M. Higgs.  2014.  Song of the burbot: Under-ice acoustic signaling by a gadoid fish.  Journal of Great Lakes Research 40: 435-440.

Cott, P.A., T.A. Johnston, J.M. Gunn, and D.M. Higgs.  2013.  Hearing sensitivity of the burbot.  Transactions of the American Fisheries Society 142: 1699-1704.

Cott, P.A., T.A. Johnston, and J.M. Gunn.  2013b.  Stability in life history characteristics among burbot populations across environmental gradients.  Transactions of the American Fisheries Society 142: 1746-1756.

Cott, P.A., T.A. Johnston, and J.M. Gunn.  2013a.  Sexual dimorphism in an under-ice spawning fish: the burbot (Lota lota).  Canadian Journal of Zoology 91: 732-740.

Tang, R.W.-K., T.A. Johnston, J.M. Gunn, and S.P. Bhavsar. 2013.  Temporal changes in mercury concentrations of large-bodied fishes in the boreal shield ecoregion of northern Ontario, Canada.  Science of the Total Environment 444: 409-416.