Aspects of Schooling Behavior in the Golden Shiner, Notemigonus Crysoleucas: Nearest Neighbor Distance, Angle of Sqimming, and Antiphasic Coupling

Many fish swim in schools at some point in their life. This behavior is beneficial for feeding and safety from predators, and may reduce energy expenditure during swimming. The hydrodynamic theory of schooling states that fish in a school take advantage of the wakes produced by other members of the school. This theory has been both supported and refuted in various studies. Using a swim tunnel, nearest neighbor distance, antiphasic coupling and the angle of swimming were studied in golden shiners {Notemigonus crysoleucas) while schooling. A plexiglass container placed inside the swim tunnel restricted fish to swimming in one plane in order to simplify behavioral observations. Swimming behavior was recorded using both still and video cameras. Infrared video was utilized for observations at night to eliminate any visual cues that might obscure interactions between fish. Nearest neighbor distance slightly increased as swimming speed increased, with average nearest neighbor distances of 4.07 cm at 0.20 m/s and 5.15 cm at 0.50 m/s. The average angle of swimming was 18.055 degrees at 0.10 m/s and 9.724 degrees at 0.40 m/s, with angle of swimming decreasing as swimming speed increased. At 0.60 m/s, adjacent fish swimming was timed and the proportion of antiphasic caudal movement was calculated and compared with non-adjacent fish. In the first five minutes of the 30-minute swimming bout, 53.9% of adjacent swimming and 33.8% of non-adjacent swimming was spent in antiphasic motion. In the last five minutes of swimming. IV 70.3% of adjacent swimming and 47.0% of non-adjacent swimming was spent in antiphasic motion. Adjacent fish did not swim in an antiphasic manner more frequently than non-adjacent fish. This suggests that schools are not making use of antiphasic behavior as an energy-saving mechanism. However, individuals spent more time within 0.5 body lengths of another fish at the end of the 30- minute swimming bout. Average length of coupling at the beginning and end of the swim was 2.6 seconds and 3.9 seconds. These results suggest that adjacent swimming may be beneficial in other ways.