Growth and Survival of Age-0 Smallmouth Bass, Walleye, and Yellow Perch When Exposed to Prolonged Temperature Fluctuations

Fish can experience dramatic, short-term temperature changes arising from various natural and anthropogenic processes including diel vertical migration, upwelling events in lakes, and along thermal effluent from power plants.  Such temperature changes can cause direct mortality, but may also have various non-lethal effects including either increasing or decreasing growth rates.  The severity and duration of temperature effects can be especially important for early life stages, as survival and growth rates influence subsequent recruitment and size distribution of the adult population.  To better evaluate these responses, we performed laboratory experiments to determine growth and survival of age-0 fingerling walleye, smallmouth bass, and yellow perch exposed to short-term temperature variation.  Each species was individually exposed to one of three treatments: a constant temperature, fluctuations of ±2 °C around the constant temperature, and fluctuations of ±4 °C around the constant temperature.  Fluctuations lasted 12 hours and were repeated over 30 days.  Each day fish were fed in excess of maximum consumption.  The percentage of fish surviving and growth rates were compared among treatments.