Comparison of mandibular with cemental growth-layer counts for ageing Atlantic walrus ( Odobenus rosmarus rosmarus )

• Published in: Canadian Journal of Zoology
• Main Authors: Garlich-Miller, J. L., Stewart, R. E. A., Stewart, B. E., Hiltz, E. A.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1993
• Subjects: Animal Science and Zoology; Ecology, Evolution, Behavior and Systematics; Odobenus rosmarus; walrus*
• Online Access: http://dx.doi.org/10.1139/z93-022; http://www.nrcresearchpress.com/doi/pdf/10.1139/z93-022

The relationship between the numbers of growth layers counted in the mandible and in the cementum of lower canines from 87 walrus (Odobenus rosmarus rosmarus) was examined. A 1:1 correlation between counts of growth layers in the two tissues was found in males ≤ 19 years old and females ≤ 9 years old. No correlation was found in males with ≥ 21 or in females with ≥ 10 cemental growth layers. In physically mature walrus, mandibular layering was unreliable for age analysis. Resorption and a reduced mandibular growth rate appear to be the main factors limiting mandibular age estimates in mature walrus.