Behavioral thermoregulation and locomotor activity of Perca flavescens

Abstract

Ten yearling yellow perch (Perca flavescens) were tested individually for 3-day periods in electronic shuttleboxes to determine their diel patterns of behavioral thermoregulation and of locomotor activity relative to a natural April photoperiod, and to determine the relationship between preferred temperatures and activity. The perch exhibited a diel rhythm of preferred temperature, with a predawn minimum of 16.7 °C and a dusk maximum of 23.8 °C. The 24-h mean was 20.2 °C; the diurnal mean was 21.5 °C and the nocturnal mean was 18.5 °C. Locomotor activity (quantified as mean photocell-monitored light-beam interruptions per hour) was crepuscular, with a major peak (25 units/h) at dusk, and a smaller peak (14.4 units/h) at dawn. Nocturnal activity was slightly greater (5.3 units/h) than diurnal activity (4.4 units/h). Locomotor activity relative to temperature exhibited a local minimum (0.4–6.2 units/h) at 22.2 °C.