Cooperative Fish and Wildlife Research Units Program: Tennessee
Education, Research and Technical Assistance for Managing Our Natural Resources

Cole, A., and P.W. Bettoli. 2014. The thermal ecology of subadult and adult muskellunge in a thermally-enriched reservoir. Fisheries Management and Ecology 21:410-420


Abstract The movement of adult muskellunge, Esox masquinongy Mitchill, has been investigated in a variety of systems; however, temperature selection by muskellunge has never been examined where well-oxygenated waters over a range of temperatures were available for much of the year. Thirty adult muskellunge, tagged internally with temperature-sensing radio tags were tracked from March 2010 to March 2011 in a Tennessee reservoir. Mean tag temperatures were 18.9°C in spring (March – May), 22.1°C in summer (June – August), 16.5°C in fall and 9.8°C in winter (December – February). When the greatest range in water temperatures was available (7.1 – 33.3°C; May – early August 2010), their realized thermal niche (mean + 1 SD) was 22.3°C + 1.8 and we detected a size effect (smaller fish selected slightly cooler temperatures) but no difference between the sexes. An electric generating steam plant discharging warm water came online in January 2011 and most (86%) tagged fish occupied the plume where temperatures were ≈ 10°C warmer than ambient water temperatures. No mortalities were observed 15 days later when plant operations ceased. Their affinity for the heated plume prompted concerns that muskellunge will be too easily exploited when the plant operates during winter.