Analyses of sea turtle landing behavior based on frequently observed coastal profile data - A case study in Enshu Coast, Japan

Abstract

This study analyses sea turtle landing behavior along a 10 km sandy beach on the Enshu Coast, Japan, facing the Pacific Ocean. Data for the analysis are sea turtles' landing positions and crawl tracks recorded by a handheld GNSS device from May to September (2011–2016), noting spawning or no-spawning activity simultaneously, supplemented by weekly cross-shore beach profiles surveyed at four locations, satellite images, and other geographical data. At the onset, landing positions on the beach are visualized to determine local concentrations along the beach. Subsequently, we estimate the distance of spawning and no-spawning positions from the waterline during landing and evaluate beach stability through the temporal elevation change standard deviation. The study found that preferred spawning locations are 40–70 m from the waterline, above the intertidal zone, on bare sand, with a standard deviation of 0.1–0.6 m. This study also highlights the impact of beach infrastructure on sea turtle spawning failures and the influence of significant wave height on sea turtle landing.