Male-biased in-water population of loggerhead turtle (Caretta caretta) in Dalyan, Turkey as a possible important marine turtle area in the Mediterranean

Abstract

In this study, we present the first in-water monitoring results of loggerhead turtles (Caretta caretta) in Koycegiz-Dalyan specially protected area (SPA), Turkey. The capture-mark-recapture (CMR) study encompassed a total of 113 capture events of 88 individuals across two sampling years. The majority of the population was adults (88.6%) with a highly male-biased (70.5%) sex ratio. Our results indicate that some of the overwintering individuals also contribute to the nesting population in the region. Biometric characteristics of captured individuals were also presented. Additionally, we found the population to be under heavy anthropogenic threats with 54.5% of the captured individuals exhibiting results of previous anthropogenically caused injuries. Our results suggest that Koycegiz-Dalyan SPA is an important overwintering and foraging area for loggerhead turtles, which is currently an indexed nesting site for loggerhead turtles in the Mediterranean. Given the possible feminization effects of climate change on future marine turtle populations, the male-biased population in the study area is of the greatest importance, and together with having an indexed nesting site, the area should therefore be regarded as an important marine turtle area.