Ecology of Larval White Bass in a Large Kansas Reservoir

Abstract

Knowledge of the early life history of sport fish is important for understanding recruitment and population dynamics. Unfortunately, little is known about the early life history of the white bass Morone chrysops. Therefore, this study was conducted to describe the spatial and temporal distribution, age structure, growth, mortality, and food habits of larval white bass in a Kansas reservoir. Larval white bass and zooplankton were sampled weekly from March to July 1999 in Glen Elder Reservoir; 92% of these fish were sampled from the upper reservoir. The larval white bass varied in age from 3 to 35 d and grew approximately 0.32 mm/d. Cohort-specific instantaneous mortality rates varied from 0.02 to 0.15. Differential mortality among early- and late-spawned fish was not apparent. The white bass first hatched during late April and continued hatching until late May. We estimated that most fish spawned during early and mid-May and that spawning activity was closely related to high reservoir inflows (10–25 m³/s). The diets of the larval white bass were dominated by adult copepods and Bosmina spp.; fish consumed adult copepods, Bosmina, and Diaphanosoma spp. in greater proportions than those available and avoided other prey taxa (e.g., Daphnia spp. and rotifers).