Meeting Abstract
Adult bluegill show variation in their morphology and swimming performance based on habitat. The littoral form has a deeper body with fins located farther from the center of mass to aid in maneuvering among the vegetation. Pelagic bluegill have a streamlined, fusiform body shape associated with efficient steady-swimming. This body shape is also associated with greater fast-start performance based on peak velocity, acceleration and turning rates. This is significant since fish that perform faster-starts should have greater fitness because they are better able to evade predators. Juvenile bluegill of both body forms hatch in the littoral habitat and remain there until they are less susceptible to predation in the open water. It is not known if there is any variation in morphology and performance in the juveniles, similar to the relationship seen in adults. Therefore, we quantified a total of 95 fish from three size classes (<50 mm, 50-80 mm, 80-120 mm TL). We measured functionally relevant morphological variables including fin areas, body area and body depth and analyzed fast-start performance from high-speed video recordings. Juvenile bluegill show variation in their morphology among each size class. Relative body depth increases from a streamlined body shape in the smallest juveniles to a relatively deeper shape in the subadult group. Juveniles also show variation in their fast-start performance. The smallest juveniles have the highest relative velocity and travel the farthest distance during the fast-start. This group is likely the most vulnerable to predation, therefore, their increased fast-start performance would increase fitness. Future studies of steady-swimming and maneuverability are needed to determine if juveniles show the same pattern of divergence in swimming performance as the adults.
