Precision and Bias of Largemouth, Smallmouth, and Spotted Bass Ages Estimated from Scales, Whole Otoliths, and Sectioned Otoliths

Abstract

We compared the precision and bias of age estimates derived from scales, whole otoliths, and sectioned otoliths and by readers of varying experience level for largemouth bass Micropterus salmoides, smallmouth bass M. dolomieu, and spotted bass M. punctulatus from Skiatook Lake, Oklahoma. Precision was assessed with the coefficient of variation of age estimates for each fish. Bias was determined among readers and structures from age bias graphs derived from least squares regression. Precision was similar among species for all three structures and among structures for any species, except for smallmouth bass; its age estimates were more precise with whole otoliths. Bias between pairs of readers was found for scales and whole otoliths among all three species but never for sectioned otoliths. The experience level of the reader influenced the bias between readers for scales but not for otoliths. Bias between structures was found between scales and whole otoliths for all three species and between scales and sectioned otoliths for smallmouth bass and spotted bass. Age estimates were unbiased between whole and sectioned otoliths for all three species. Although sectioned otoliths required more preparation time, they provided the best age estimates for the three populations in Skiatook Lake.