Precision of Ages Estimated from Five Bony Structures of Arctic Char (Salvelinus alpinus) from the Wood River System, Alaska

Abstract

Ages of 32 Arctic char (Salvelinus alpinus) were estimated from otoliths (surface-examined and broken-and-burned), vertebrae, cleithra, opercula, and subopercula. Six readers examined each structure three times, and the precision of these estimates among structures and readers was compared with means, aging differences, and analyses of variance. Surface-examined otoliths provided the most precise age estimates and were one of the easiest structures to prepare and read. Broken-and-burned otoliths produced less precise estimates for larger, older Arctic char than for smaller, younger Arctic char. Based on lack of precision, cleithra should probably not be used to age Arctic char. Although mean estimates for the five structures were not significantly different, surface-examined otoliths produced older age estimates than break and burn otoliths. We feel that surface-examined otoliths are best for precise estimation of age of Arctic char but recommend that both otolith methods be compared when aging Arctic char older than 8 yr. Scales were also examined from 30 Arctic char but were not included in the analyses after preliminary examination because age was difficult to interpret (circuli were clear on all scales, but only two or three annuli of uncertain significance could be distinguished).