Effects of Water Velocity on Activity Patterns of Juvenile Striped Bass

The activity of 10, 25, and 50-mm juvenile striped bass exposed to water velocities ranging from static to 27 cm/sec was analyzed to determine mobility, feeding response, positional orientation, and group interaction. Increased water velocity reduced the area traveled per unit time. Presence of food also reduced the area traveled. Rheotaxis, the orientation of a swimming fish with respect to the direction of stream flow, was variable at low velocities. At water velocities of 15 and 27 cm/sec positive rheotaxis occurred frequently, while lateral and negative rheotaxis were infrequently observed. Distance between fish, a measure of group interaction, decreased with increasing water velocity and also decreased with the addition of food.