Fig. (3) Age-dependent within- (Reader 1 = a, b; Reader 2 = c, d) and between-reader (e, f) mean coefficients of variation for ages estimated for smallmouth bass (left panel) and walleye (right panel) otoliths. Open circles represent values for otoliths viewed using the otolith illumination device whereas filled circles represent values for otoliths viewed using an alternative method. Error bars represent one standard error of the mean.