Contents lists available at ScienceDirect Journal of Sea Research journal homepage: www.elsevier.com/locate/seares Haplotype and biometric patterns in loggerhead turtles from the Adriatic foraging ground Valentina Bertuccio a,b , Federica Costantini a,b,c, ⁎ , Valeria Angelini d , Giovanni Furii e , Karin Gobic f , Marco Abbiati b,c,g,h a Dipartimento di Scienze Biologiche, Geologiche ed Ambientali (BiGeA), University of Bologna, Italy b Centro Interdipartimentale di Ricerca per le Scienze Ambientali (CIRSA), University of Bologna, Italy c CoNISMa, Piazzale Flaminio 6, Roma, Italy d Fondazione Cetacea onlus, Riccione, Italy e Centro Recupero Tartarughe Marine Legambiente, Manfredonia, Italy f Marine Educational Centre, Pula, Croatia g Dipartimento dei Beni Culturali (DBC), University of Bologna, Italy h Consiglio Nazionale delle Ricerche, Istituto di Scienze Marine, ISMAR, Bologna, Italy ARTICLE INFO Keywords: Caretta caretta Body size Mixed stock analysis Genetic structuring Mediterranean Sea Conservation ABSTRACT The Adriatic Sea is an important foraging area for the loggerhead turtle Caretta caretta. Due to the increase of anthropogenic impacts, a growing number of individuals are captured as by-catch, found stranded or drifting at sea. Turtles mortality within the Adriatic Sea can affect Mediterranean populations, increasing the risk of losing genetic diversity. Biometric data on 93 loggerheads from three Adriatic areas (northwestern, northeastern and southern Adriatic) and patterns of sequence polymorphism of the mtDNA Control Region long fragment were used to investigate the sizes/age distribution of the collected individuals and to assess their geographic origins by using a Bayesian Mixed Stock Analysis (MSA). The biometric data revealed that collected turtles belonged to a wide range of sizes, although juveniles and subadults were the most abundant classes. Five haplotypes were detected. Two are endemic of Mediterranean rookeries and one is a rare haplotype found once in a Floridian rookery and in two Mediterranean nests. The other two haplotypes were found both in Atlantic and Mediterranean populations. The Mixed Stock Analysis revealed the presence of individuals from Greek and Turkish rookeries, this latter group was found in the southern Adriatic. Individuals from Libya and Cyprus rookeries were also found in the Adriatic stock. Current patterns, juvenile natal homing and imprinting of on- togenetic habitats could be potential drivers of the stock composition in the three Adriatic areas. Variations of turtle migration patterns, recruitment and mortality may drive differential contributions of rookeries to the foraging grounds. In this study, a substructuring within the Adriatic basin is hypothesized, consisting of dif- ferential distribution of stocks among three areas. However, these results might be biased by the uneven sample size among areas. Further studies with consistent sample sizes are recommended to quantify potential genetic differentiation within the Adriatic Sea. Nevertheless, present results recommend preservation action to be taken both at the nesting sites and in the foraging grounds were genetically isolated Caretta caretta populations, ori- ginating from different Mediterranean rookeries, mix together. 1. Introduction In the last century, the increasing of fishing effort affected marine ecosystems worldwide (Jackson et al., 2001). Many no target species are entangled or hooked through incidental catches (by-catch) by fisheries (Lewison et al., 2004). For species like marine mammals and marine turtles, by-catch is a serious conservation issue (Casale, 2011; Casale et al., 2018; Lewison et al., 2004), as the accidental take can lead populations to an unperceived worldwide decline over short time (Casey and Myers, 1998; Lewison et al., 2004). The loggerhead turtle Caretta caretta is the most common marine turtle species in the Mediterranean Sea. Late sexual maturity over https://doi.org/10.1016/j.seares.2019.02.002 Received 26 October 2017; Received in revised form 21 January 2019; Accepted 11 February 2019 ⁎ Corresponding author at: Dipartimento di Scienze Biologiche, Geologiche ed Ambientali (BiGeA), University of Bologna, Via S. Alberto 163, I-48123 Ravenna, Italy. E-mail address: federica.costantini@unibo.it (F. Costantini). Journal of Sea Research 147 (2019) 1–9 Available online 13 February 2019 1385-1101/ © 2019 Elsevier B.V. All rights reserved. T