Publication Type: | Journal Article |
Year of Publication: | 2007 |
Authors: | King, JC, Gelatt, TS, Pitcher, KW, Pendleton, GW |
Journal: | Marine Mammal Science |
Volume: | 23 |
Pagination: | 262-271 |
Date Published: | 2007 |
ISBN Number: | 1748-7692 |
Keywords: | Panthera leo |
Abstract: | Studies of health, survival, and development of juvenile Alaskan Steller sea lions (Eumetopias jubatus, SSL) require accurate estimates of age for wild-captured animals. However, the value and accuracy of several potential predictors of age have not been assessed with data from known-age free-ranging animals. During 2001–2005, forty-six individual SSL originally branded or tagged at ≤6 mo of age were recaptured by the Alaska Department of Fish and Game (ADF&G). Using a series of general linear models, we evaluated the ability of morphometrics measurements: permanent canine tooth length (CTL), diastema (DIAS), whisker length (WHIS), and dorsal standard length (DSL) to predict the age of forty-six known-age juveniles (n= 46 ≤23 mo of age). Permanent CTL was the strongest individual predictor (r2= 0.80); followed by DSL, DIAS, and WHIS (r2= 0.70, 0.56, and 0.45, respectively). The inclusion of a single sample from a 44-mo-old sea lion suggested quadratic relationships between age and all predictors for older animals. Only models including CTL predicted age to within 6 mo of known age. The equation Age = (−3.0112 +[0.6726 * CTL]+[0.4965 * DIAS]) allows for accurate age estimates of SSL ≤23 mo for both sexes. |
URL: | http://dx.doi.org/10.1111/j.1748-7692.2007.00108.x |
A FIELD-BASED METHOD FOR ESTIMATING AGE IN FREE-RANGING STELLER SEA LIONS (EUMETOPIAS JUBATUS) LESS THAN TWENTY-FOUR MONTHS OF AGE
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