Skeletochronology, age at maturity and cause of mortality of loggerhead sea turtles Caretta caretta stranded along the beaches of Campania (south-western Italy, western Mediterranean Sea)

Abstract

Information on demographic and life-history traits of endangered vertebrate species, such as sea turtles, is crucial for planning management and conservation actions. We applied skeletochronology of phalanges to estimate the age of loggerhead turtles, Caretta caretta, found dead stranded along the beaches of Campania (western Mediterranean) from 2013 to 2017. To obtain maturity data, we examined gonads from a subsample of 7 males and 11 females. Overall, curved carapace length (CCL) ranged from 5.6 to 90.8 cm, but for most turtles (89%) it was 50–79.9 cm. Predominance of stranded females (62%) was recorded. Ten out of the eighteen histologically examined gonads allowed estimating maturity. Based on the lines of arrested growth counting, the estimated age of the examined specimens ranged from 0 (hatchling) to 26 years. The modal age was 14 years for males and 17 years for females. The smallest male with spermatogenetic activity had a CCL of 65 cm and was estimated to be 16 years old. The smallest female with follicular development stage, characterising the transition towards adulthood, had a CCL of 69.5 cm and was estimated to be 20 years old. Anthropogenic factors were responsible for 36% of the mortality of individuals, followed by parasitic/infective pathologies (20%).