A comparison of three structures for estimating the age of yellow perch

The ability to determine the age of fish precisely is essential to understanding the structure and dynamics of fish populations. The goal of this study was to compare three hard structures (scales, otoliths, and dorsal fin spines) for estimating the ages of yellow perch Perca flavescens in an unexploited population in a sanctuary of Pymatuning Reservoir, Pennsylvania. Scales, dorsal fin spines, and sagittal otoliths were removed from 107 yellow perch, prepared, and examined by two independent readers. Ages assigned by the two independent readers agreed 96% of the time when using otoliths, 83% when using scales, and 80% when using spines. Pairwise comparisons (paired t-tests, α = 0.05) indicated no significant differences among the ages assigned using the three methods. Otoliths were the best structure to use for estimating yellow perch age based on high reader agreement and low coefficient of variation (CV). However, we found that scales and dorsal fin spines can be used to adequately describe the age structure of yellow perch populations (CV < 10% for each structure), although dorsal fin spines were slightly more precise than scales for fish assigned to age 4 or older by using otoliths. Thus, use of both dorsal fin spines and scales for yellow perch age and growth studies may improve the precision of population age structure estimates.