Sea Turtle Survey and Restoration Assesment at the Dongsh Atoll

Project Duration	2011-01-02 ~ 2011-12-29
Research Title	Sea Turtle Survey and Restoration Assesment at the Dongsh Atoll
Contracted Organization	National Taiwan Ocean University
Principal Investigator	Cheng Yi-Chun
Project Participants	Chen He-Chang, Tseng Cheng-Tsung, Wang Hsiao-Wen, Feng Chia-Ling, Kuo Fu, Chang Chi-Ming, Chiu Ching-Yung, Hsu Ching-Wei, Chen Jung
Keywords	Dongsha, green sea turtle, nesting habitat, Sea Turtle Rescue and Rehabilitation Center
Abstract	Dongsha Atoll was once an important foraging and nesting habitat for green sea turtles and hawksbill turtles in the South China Sea. However, due to overdevelopment and destruction of terrestrial and marine habitats, sea turtle populations have declined to near-endangered levels, and nesting turtles are now rarely observed on the beaches. In addition, sea turtles within Dongsha Atoll frequently require rescue and medical treatment due to fisheries bycatch, disease, injury, and other natural or anthropogenic factors. The rescue and rehabilitation of injured turtles are crucial for the persistence of the local sea turtle population. This project aimed to investigate sea turtle species composition, population status, distribution within the atoll, nesting habitat distribution and environmental factors, and survival threats. The project also assisted the Marine National Park Headquarters in establishing a “Sea Turtle Rescue and Rehabilitation Center” and organized an international symposium on sea turtle rescue and health assessment to enhance domestic capacity for wildlife rescue and care. Based on the findings, the feasibility of designating protected sea turtle habitats was evaluated. Two species were recorded within Dongsha Atoll: the green sea turtle and the hawksbill turtle. Dongsha likely serves as an important habitat for subadult turtles. However, due to environmental constraints and limited resources, reliable population size estimation was nearly impossible. Interviews suggested that sea turtles are more frequently observed in waters off the eastern side of Dongsha Island. Environmental assessments of nesting habitats indicated that most beaches on Dongsha Island are suitable for nesting and egg incubation, except for the northern shore between the Third Outpost and the incinerator (where beach depth is too shallow) and the Eighth Outpost area (where construction debris accumulates). Sand temperatures at approximately 70 cm depth appear suitable for incubation, although they may result in a higher proportion of female hatchlings. Accumulated seagrass on beaches does not significantly hinder nesting activity. Identified survival threats include coastal armoring blocks causing terrestrialization of beaches, the near “ecological extinction” of nesting female populations, the near disappearance of hawksbill turtles, insufficient training of island personnel in handling protected wildlife, ongoing illegal marine turtle hunting, and degraded coral reef habitats unsuitable for turtle habitation. The report also provides standard operating procedures and survey forms for on-site sea turtle investigations and rescue operations. The Sea Turtle Rescue and Rehabilitation Center has been fully planned and construction initiated. Short-, medium-, and long-term operational plans were proposed. Additionally, a two-day “Taiwan International Sea Turtle Rescue and Health Assessment Conservation Symposium” was held on October 5–6, 2011, at Kenting National Park Headquarters and the National Museum of Marine Biology and Aquarium, with participation from 93 individuals representing 39 institutions. The symposium provided basic health assessment training for national park personnel and promoted the establishment of a national sea turtle rescue reporting network, fostering collaboration between sea turtle biologists and veterinarians. Finally, five conservation measures were proposed to address survival threats faced by sea turtles in Dongsha Island and surrounding waters. Although both green and hawksbill turtles in Dongsha are endangered and habitat protection is necessary, current environmental constraints and insufficient population data make immediate designation of a protected area challenging. Effective protection will require several years of coordinated efforts between the Marine National Park Headquarters and the Coast Guard Administration to remove coastal armoring blocks and to accurately identify marine distribution patterns and hotspot areas before establishing a viable protected zone.