Age and growth of juvenile green turtles Chelonia mydas in the western South Atlantic Ocean

The green turtle Chelonia mydas has a circumtropical distribution and is globally endangered. This long-lived, migratory turtle has a spatially complex life cycle that encompasses initial development in oceanic habitat, with subsequent recruitment to neritic habitat. In the coastal waters of the western South Atlantic Ocean, juvenile green turtles are a notable component of the marine megafauna. As a result of incidental capture and other anthropogenic causes, dead specimens are commonly found stranded on beaches. Knowledge of age and growth is critical to understanding population life history and dynamics, as well as for conservation planning. We applied skeletochronology to estimate age and growth rates for green turtles stranded throughout 16 yr (1994 to 2010) in southern Brazil. Curved carapace length (CCL) ranged from 31 to 61 cm (mean = 41 cm) and estimated ages from 2 to 13 yr (mean = 5 yr, mode = 3 yr). Green turtles recruit to the neritic environment in this area around 30 cm CCL and aged 2 to 3 yr, remaining in this region until reaching about 50 cm and 7 yr. The mean growth rate of the whole sample was 3.7 cm CCL yr(-1), and both age and size had a significant influence on growth.