Precision of hard structures used to estimate age of mountain Whitefish (Prosopium williamsoni)

Western North American Naturalist
By: , and 



The mountain whitefish (Prosopium williamsoni) is a widely distributed salmonid in western North America that has decreased in abundance over portions of its distribution due to anthropogenic disturbances. In this investigation, we examined precision of age estimates derived from scales, pectoral fin rays, and sagittal otoliths from 167 mountain whitefish. Otoliths and pectoral fin rays were mounted in epoxy and cross-sectioned before examination. Scales were pressed onto acetate slides and resulting impressions were examined. Between-reader precision (i.e., between 2 readers), between-reader variability, and reader confidence ratings were compared among hard structures. Coefficient of variation (CV) in age estimates was lowest and percentage of exact agreement (PA-0) was highest for scales (CV = 5.9; PA-0 = 70%) compared to pectoral fin rays (CV =11.0; PA-0 = 58%) and otoliths (CV = 12.3; PA-0 = 55%). Median confidence ratings were significantly different (P ≤ 0.05) among all structures, with scales having the highest median confidence. Reader confidence decreased with fish age for scales and pectoral fin rays, but reader confidence increased with fish age for otoliths. In general, age estimates were more precise and reader confidence was higher for scales compared to pectoral fin rays and otoliths. This research will help fisheries biologists in selecting the most appropriate hard structure to use for future age and growth studies on mountain whitefish. In turn, selection of the most precise hard structure will lead to better estimates of dynamic rate functions.

Publication type Article
Publication Subtype Journal Article
Title Precision of hard structures used to estimate age of mountain Whitefish (Prosopium williamsoni)
Series title Western North American Naturalist
DOI 10.3398/064.075.0102
Volume 75
Issue 1
Year Published 2015
Language English
Publisher Monte L. Bean Life Science Museum, Brigham Young University
Contributing office(s) Coop Res Unit Seattle
Description 7 p.
First page 1
Last page 7
Online Only (Y/N) N
Additional Online Files (Y/N) N
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