How Old Is a Turtle? Challenges in Interpreting Age Information in Sea Turtles

Marine turtles are iconic, globally distributed large reptiles with a largely oceanic life history that makes it difficult to characterize population demography and dynamics. This is significant because all marine turtle species are currently considered vulnerable or endangered. Knowledge of the age of individuals is central to our understanding of the life history of a species and an important consideration in the design of management and conservation strategies. Herein, we review different methods used to estimate the absolute, relative and physiological age of marine turtles, as well as their underlying hypotheses and challenges in their interpretation. We conclude that, at present, there is no validated method that establishes the absolute age of an individual from field studies.