Movements of Green Turtles (Chelonia mydas) Rescued from Pound Nets Near Jeju Island, Republic of Korea

Green turtles (Chelonia mydas) are observed year-round in the Sea of Jeju Island, Republic of Korea; however, there is limited information on their migration and seasonal distribution outside of Korean waters. To investigate their spatial and temporal movement, we tracked 8 green turtles (straight carapace length range, 49.7-85.9 cm; mean +/- SD, 63.36 +/- 10.99 cm), taken as bycatch in pound nets near Jeju Island, using satellite transmitters from August 2015 to January 2017. Turtles were mainly juveniles and were tracked for 17-314 d. Three turtles traveled more than 400 km from their release site in 2 different directions: one individual moved westward to China within 17 d of release, and 2 individuals traveled eastward to Japan. One turtle that moved to Japan had been flipper-tagged at Kagoshima, Japan, 1 mo prior to its capture at Jeju Island. The other 5 individuals remained near the coast of Jeju Island. The individual tracked for the longest period (314 d) overwintered (water temperature, 12 degrees-14 degrees C) in the eastern area of Jeju Island. These results indicate that green turtles from different regions, including China and Japan, may use the areas around Jeju Island for foraging, for overwintering, and/or as a migratory corridor. To fortify the conservation of green turtles in the region, international cooperation and expanded research efforts, such as genetic studies, are needed.