Palmetto Bass Movements and Habitat Use in a Fluctuating Colorado Irrigation Reservoir

Abstract

Movement and habitat use by adult palmetto bass (female striped bass Morone saxatilis × male white bass M. chrysops) were monitored with ultrasonic transmitters in a 1,166-ha fluctuating irrigation reservoir in eastern Colorado. Movement varied by diel periods, and heterogeneity was recorded among individuals. Minimum estimates for displacement ranged from 30 to 558 m/h. Factors that appeared to influence movement included water clarity, water temperature, and barometric pressure, although these relationships explained little variability in the multiple-regression model used. Palmetto bass exhibited a preference for nearshore areas, but they did not select for cover types within that region. As the water level in the reservoir was reduced through irrigation drawdown, the fish used deeper areas of the lake than during periods of water level stability. Knowledge of the influence of these variables on activity patterns should help improve catch rates for anglers and sampling efficiency for biologists.