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Sea turtle abundance estimates are often based on nest numbers or female-tagging projects. However, because male sea turtles do not emerge on the beach and are difficult to observe at sea, the number of males contributing to the breeding population is difficult to characterize. Using a molecular approach like genotyping hatchings to infer paternal genotypes can provide an indirect estimate of breeding male population size. This would help to estimate operational sex ratios, which is of vital significance for the conservation of sea turtle populations. We investigated the pattern of multiple paternity and reconstructed paternal genotypes in the largest green turtle nesting site of the Mediterranean, Akyatan beach, Turkey, using nine dinucleotide microsatellite loci. We genotyped 22 randomly selected unique female green turtles (approx. 33.3% of all nesting females during 2009 nesting season) and tissue biopsies from 15 hatchlings from each of their nests n = 330). We identified multiple paternity in 59-63.6 % of the nests analysed and identified 68 individual males that had sired offspring within these nests. The operational sex ratio within our sample of the population was 1 female for every 3 males. We found 3 repeating males (males that sired offspring with more than one female) in 6 clutches resulting in 11 paternal sibships. (C) 2019 Elsevier B.V. All rights reserved.