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ACCURACY OF AGE DETERMINATION IN THE GREY SEAL HALICHOERUS GRYPUS OF EASTERN CANADA
Author(s) -
Mansfield A. W.
Publication year - 1991
Publication title -
marine mammal science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.723
H-Index - 78
eISSN - 1748-7692
pISSN - 0824-0469
DOI - 10.1111/j.1748-7692.1991.tb00549.x
Subject(s) - range (aeronautics) , population , age groups , reference values , biology , geography , zoology , demography , medicine , materials science , sociology , composite material
A bstract The ages of 82 grey seals of known age from 1 to 10 yr were determined from growth layer groups in the cementum, readily seen in longitudinal sections 150 μm thick viewed under transmitted light. The sample of teeth was read five times in a series of blind replicates. With only one reading, an accuracy of 84% was achieved. This increased to 93% on the basis of three readings but improved only marginally to 94% when all five readings were considered. Accuracy was best in the middle range of ages (3–6 yr) which are the critical years for estimating age‐specific reproductive rates in population models.