Table 4.

A comparison table of aging studies using teeth, CV = coefficient of variation, D = index of precision.

Study	Common name	Age ranges	Aging method	Age determination	CV (Reader 1/2)	D (Reader 1/2)	Validation
This study	California sea lion	<1–30 yr old	Acid etched upper canine	Median of 3 readings	19.6/17.2	11.3/9.9	55/61% aged within 1 yr of actual age
Bowen et al. 1983	Harp seal	3 mo–10 yr old	Thin-sectioned lower canine	Mean of 5 readings	n/a	n/a	83.4% aged exactly (mostly young animals)
Mansfield 1991	Gray seal	1–10 yr old	Thin-sectioned lower canine	2/3 repeated readings used or 3+/5 repeated readings used	n/a	n/a	93% aged exactly for 3 readings and 94% for 5 readings
Bernt 1996	Gray seal	2–20 yr old	Thin-sectioned incisor	2/3 repeated readings used or mean of 3 readings	n/a	n/a	83%, 63%, 93% aged exactly by readers 1, 2 and 3
Childerhouse et al. 2004	New Zealand sea lion	4–15 yr old	Thin-sectioned postcanine	2/3 repeated readings used or mean of 3 readings	n/a	n/a	55% aged within 1 yr of actual age
Christensen-Dalsgaard et al. 2010	Polar bear	1–15 yr old	Thin-sectioned premolar	3 readings	18.2/15.2	n/a (used a linear regression model)	50/53% aged within 1 yr of actual age