Research Training Program

Smithsonian Institution
National Museum of Natural History

PROJECT SUMMARY
1996

Richard E. Glor
Cornell University
Ithaca, New York

George R. Zug, Ph.D.
Supervising Scientist
Department of Vertebrate Zoology
Division of Reptiles and Amphibians
"The research training program has been the most intense educational experience of my life. I will remember and benefit from it for the rest of my life."

Age and Growth Estimates of Indian River Green Sea turtles (Chelonia mydas): A Skeletochronological Analysis

ABSTRACT
The goal of this project was to determine the age and growth pattern for a population of juvenile Green sea turtles found in the Indian River Inlet along the east coast of Florida. As in any organism, the age at maturity and growth rate for this endangered sea turtle have important life history and conservation implications. Unfortunately, however, the sea turtles' marine existence and migratory habits make it difficult to directly collect age and growth data. For this reason, this analysis relied upon an indirect technique known as skeletochronology. This technique utilizes the annual rings of growth present in the bones of turtles (similar to the rings found in trees) to estimate age. Once the age and its relationship to size have been determined, it is possible to construct a growth model for the population. The results of this analysis suggest that the immature turtles in the lagoon are between three and fourteen years of age. This indicates that the turtles are living a pelagic and/or nearshore existence for the first three years of their lives and are leaving the lagoon at fourteen years of age just prior to maturity to travel to an unknown location. Estimates of growth also show that these turtles are growing at a relatively steady rate of about 40 mm/year. Although this analysis did not include any adult turtles, extrapolation from the data indicate that this species does not reach maturity until at least 25 years of age. A summary of what is currently known of developmental colonies and their role in the life cycle of the Green sea turtle has also been included.

This research was supported by a grant from the National Science Foundation Research Experiences for Undergraduates program, Award Number DBI-9531331.

Letter of Gratitude