A 21-year recovery trend in green turtle nesting activity: 2002-2022

Abstract

Long-term monitoring and conservation are crucial for effective protection, since sea turtles migrate cyclically every 2–3 years and lay multiple nests during a breeding season. Therefore, this study aimed to investigate the long-term trend of nesting activities of green turtles over a 21-year period (2002–2022) on Samandağ beach. An early morning survey was conducted every year during both nesting and hatching seasons. The trend analyses in nesting activities were performed using Mann–Kendall and Sen's slope tests together with the augmented Dickey–Fuller stationarity test. The nest count and female abundance increased significantly, whereas clutch size, fecundity, and hatching success tended to decrease insignificantly. The percentage change between the most recent and oldest 3-year mean nest count and mean female abundance, which is performed to comply with the Red List assessment method used by the International Union for Conservation of Nature Marine Turtle Specialist Group, was 769% and 764% respectively. Samandağ nesting population accounts for one-third of the Mediterranean's total nest count and one-fourth of its total female abundance. The decrease in clutch size and fecundity may be due to the recruitment of individuals with smaller body sizes or malnutrition as a result of population growth. There was an increase in the number of dead embryos and a decline in hatching success. This may be explained by density-dependent population regulation as a result of an increase in the number of nests. It may be argued that adherence to a uniform strategy and the maintenance of continuous protection through collaboration with governmental and non-governmental organizations with scientifically rigorous methodology are significant factors contributing to the high recovery. This study emphasizes the necessity of adopting a comprehensive conservation approach encompassing both foraging habitats and the significant role played by the population in Samandağ in the proliferation of Mediterranean green turtles.