Comparison of Sectioned and Whole Otoliths for Estimating Bluegill Age

Abstract

Abstract Three readers independently assigned ages to 257 paired sectioned and whole Bluegill Lepomis macrochirus otoliths to examine between-reader precision of age estimates and to compare estimates obtained using the two otolith preparation methods. Percent exact between-reader agreement varied from 93.4% to 96.9% for sectioned otoliths and 92.2% to 94.2% for whole otoliths. Mean coefficient of variation values for between-reader comparisons were < 5.0% for all reader combinations and both otolith preparation methods. Exact agreement between paired whole and sectioned otoliths varied by reader from 82.8% to 85.2%; whereas coefficient of variation values ranged from 7.8% to 8.9%. The only significant departure from a 1:1 relationship for mean age estimates between the two preparation methods occurred for young fish in the estimates of one reader. This bias was not pervasive, as no significant bias was indicated in older fish. Our results suggest that age estimates obtained from sectioned and whole Bluegill otoliths are precise and the time and associated expense of mounting and sectioning Bluegill otoliths may not be necessary as whole otolith ages were generally concordant with sectioned ages to age 8 y.