  Body mass is a major life history trait and provides a scale for all living
processes of organisms. Unfortunately body mass cannot be easily measured for
many species, because of the logistical difficulties involved in actually
catching and weighing them. This is particularly true for sea turtles which are
large vertebrates that spend most of their life at sea. Here we developed a
general linear model to predict body mass from 17 morphometric measurements
obtained from 49 leatherback turtles nesting in Awala Yalimapo beach, French
Guiana, South America. A stepwise backward analysis removing independent
parameters with P > 0.001 indicated that body mass can be estimated with 93%
accuracy by Body Mass (kg) = - 709.146 + 3.391MedianBodyCirc (cm) + 2.664SCCL
(cm), where SCCL is the standard curvilinear carapace length and MedianBodyCirc
is body circumference at half of SCCL. A sensibility test showed that this
parsimonious model is robust, as estimated body mass may change by 0.7-1.3% for
1-2 cm changes in SCCL, by 0.9-1.7% for 1-2 cm changes in circumference.
Leatherback turtles from French Guiana were larger and heavier than in all
other nesting sites studied so far, suggesting either that gravid leatherbacks
feed during the nesting season in French Guiana, and/or that this species may
exhibits site-specific growth strategies. Further studies are required to test
these hypotheses, including implementation of similar simple models for other
nesting populations, in order to better understand the life history of this
endangered species.
