Using Dorsal Spines to Estimate Percid Age: Are All Spines Created Equal?

Dorsal spines are often used to estimate the age of walleyes Sander vitreus and yellow perch Perca flavescens. Spine selection has varied among studies and in some cases multiple spines are removed from the same fish over time, but we found no study verifying that all dorsal spines from an individual walleye or yellow perch exhibit the same number of discernible annuli.  Our objective was to determine if the first 5dorsal spines from individual walleyes and yellow perch were similar in appearance and yielded similar age estimates.  We found no difference in age estimations among spines for walleye and yellow perch.  Walleye clarity ratings did not differ among spines, but the first dorsal spine for yellow perch had significantly lower clarity ratings than the 4^th and 5^th dorsal spine.  Any dorsal spine provided the same age estimate for walleye and yellow perch, but we suggest that the first dorsal spine should not be used for yellow perch due to its relatively small size and poor clarity.