Degree Name

Master of Science (MS)

Semester of Degree Completion


Thesis Director

Leonard Durham


Daily rings were found to occur in the otoliths of laboratory-reared, young-of-the-year largemouth bass, Micropterus salmoides, for at least 151 days after swimup. Ring formation began at hatching but the total complement of prolarval rings was visible for only 10-15 days after swimup. Subdaily rings were visible in the posterior field but were easily distinguished from daily rings. Both high and low contrast tissue was present in otoliths from fish over 45 days old. Sagittal sections were superior to frontal sections for aging bass. The accuracy of the two-sections was similiar but sagittal sections were much easier and faster to prepare and considerably more readable. Otolith growth was directly proportional to body growth and the y-intercept was not substantially different from O. Daily rings were used to determine the spawning interval of largemouth bass in Lake Shelbyville, a reservoir in central Illinois, and to calculate growth rates of young-of-the-year bass from two different areas of the reservoir. The estimated spawning interval of largemouth bass in Lake Shelbyville lasted from 26 April to 19 June. Mean calculated growth rates for each collection of young-of-the-year bass varied from 0.88 to 1.14 mm per day. By mid September young-of-the-year bass had grown significantly faster at the upper end of the reservoir than at the lower end. Differential mortality between early and late spawned bass did not occur between mid June and mid September.