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%).
Highlights
Accurate information on the age at sexual maturity and longevity of individuals is crucial for understanding the structure of a population in its natural environment and implementing appropriate strategies for the management and conservation of threatened species (Avens et al 2017)
The majority of the specimens analysed in this study (~82%) fell between 50 and 79.9 cm carapace length (CCL)
We hypothesise that this body size range characterises the neritic stage of C. caretta in the western Mediterranean Sea and that individuals with CCL < 50 cm or > 80 cm (18% of our sample) can only be found occasionally
Summary
Accurate information on the age at sexual maturity and longevity of individuals is crucial for understanding the structure of a population in its natural environment and implementing appropriate strategies for the management and conservation of threatened species (Avens et al 2017). This is especially important for species that are still understudied or can be considered model organisms in different fields of biology (Blackburn 2006; Camargo et al 2010; Mezzasalma et al 2016, 2017a, b; de Miranda 2017). Among the most probable causes of the decreasing trend of the Mediterranean populations of this species are the degradation of coastal and open sea habitats, the prolonged illegal trade, and fishery bycatch (Lutcavage et al 1997; Margaritoulis et al 2003; Casale et al 2004; Mingozzi et al 2007)
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