Skip to main content

Be a Marine Mammal Hero

Hungry pups like elephant seal Davey are pouring through our doors. Yes, we are in the swing of pupping season, and that’s why your help is urgently needed.

What if I told you there’s a simple way you can have double the impact for good?

Today, your gift will help provide what a pup like Davey needs: double the fish meals to regain his strength for a second chance at life. How? Because your gift will be matched dollar-for-dollar up to $5,000 when you give by Sunday, June 1.

Double my impact!
Elephant seal pup, Davey
California sea lion with mouth open, showing teeth

Using Tooth Layers to Determine California Sea Lion Age

Accuracy and precision of age determination using growth layer groups for California sea lions (Zalophus californianus) with known ages
  • Aging
  • Teeth

Abstract

Age determination from counts of growth layer groups (GLGs) in tooth dentine is a common method for aging marine mammals. Using known‐aged animals, we validated this method for acid etched teeth of California sea lions (CSLs), Zalophus californianus. Between 1991 and 2013, the upper left canine (n = 33) was collected opportunistically during necropsy from animals tagged or branded as pups that later died. Overall, 55%–61% of age estimates by GLG counting were within 1 yr of the known‐age in the sample of 1–30‐yr‐old CSLs. Accuracy of age estimates was found to be dependent on age of the CSLs, however. 71%–79% of age estimates were within 1 yr of the known‐age in CSLs <10 yr old. These findings support the validity of counting GLGs to estimate age for CSLs <10 yr old to within 1 yr of accuracy. 


Rust, L.B., Danil, K., Melin, S.R. and Wilkerson, B. (2019), Accuracy and precision of age determination using growth layer groups for California sea lions (Zalophus californianus) with known ages. Mar Mam Sci, 35: 1355-1368. doi:10.1111/mms.12605

aging
teeth

See More Publications

Recent News