COMPARISON OF OTOLITH AND SCALE AGES FOR YELLOW PERCH FROM LAKE MICHIGAN

The age composition of the yellow perch (Perca flavescens) population in Lake Michigan is assessed annually by five management agencies, but all agencies do not use the same structure to estimate ages. The reli ability of the most commonly used structure, scales, has not been form ally evaluated for this population. We compared ages estimated by thre e readers from scales and sagittal otoliths for 150 yellow perch from southwestern Lake Michigan. The maximum age of yellow perch determined from scales and otoliths was 12. Otoliths had better precision (repro ducibility) and usually had more annuli than scales for all three read ers. Scale ages were usually younger than otolith ages when otolith ag es were greater than or equal to 7. Chi-square tests revealed signific ant differences (P <0.05) between the age distributions determined fro m scales and otoliths for two of the three readers. We recommend use o f otoliths for aging Lake Michigan yellow perch greater than 150 mm in length because of greater precision, easier readability, and detectio n of more annuli.