Regional comparison of leatherback sea turtle maturation attributes and reproductive longevity

Data characterizing somatic growth patterns and the ages and sizes at which organisms mature are fundamental to understanding population dynamics. However, obtaining this information for endangered leatherback sea turtles ( Dermochelys coriacea ) is particularly challenging due to unusual physiology and prevalence of remote oceanic habitat use, which limit direct observation. While inference has been made through indirect approaches such as captive, genetic, and/or skeletal growth mark (skeletochronology) studies, these diverse methods have yielded similarly varied results, limiting usefulness of available information for management and conservation. To address this data gap, we conducted refined skeletochronological analysis of Atlantic and Pacific leatherback scleral ossicle bones, allowing estimation of carapace length-at-age relationships throughout individual turtles’ lives, including the juvenile life stage. In addition, this improved approach made it possible to estimate mean and range for age and size at sexual maturation (ASM and SSM, respectively), as well as post-maturation longevity. Updated mean ASM estimates from the current study of 17–19 years were lower than those previously proposed using skeletochronology and more similar to predictions from captive growth and genetic data. Maximum estimates of reproductive longevity (18–22 years) were consistent with the 16–19 years reported previously from mark–recapture of nesting females. Together, these results indicate that the application of the refined analytical approach described in the current study may offer opportunities to increase understanding of leatherback age and growth.