Relationship between respiration rate of juvenile brook trout (Salvelinus fontinalis), water temperature, and swimming characteristics

We estimated the cost of spontaneous swimming and the swimming characteristics of juvenile brook trout for 21 combinations of water temperature (3.5, 6, 9, 12, 15, 18, and 20.7 degrees C) and respirometer volume (27, 54, and 108 L). Spontaneous swimming costs were estimated as the oxygen depletion in the respirometers corrected for biological oxygen demand of the water and standard metabolism of the fish. Spontaneous swimming costs varied 9-fold among our experiments. Swimming characteristics, such as the average and the variance of speed, acceleration, and turning rates, were determined using a pair of video cameras. Swimming characteristics varied 2- to 10-fold among experiments. Speed and turning rate tended to increase with water temperature up to 18 degrees C and decreased at 20.7 degrees C. Water temperature (r(2) = 0.44) was the only variable that could explain a significant portion of the variations of spontaneous swimming costs between 3.7 and 20.7 degrees C. Variance of speed (partial R(2) = 0.32) and the average turning rate (partial R(2) = 0.34) explained 53% of the variation between 3.7 and 18 degrees C. Average speed never explained more than 35% of spontaneous swimming cost variation.