Activity

　
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'The Research Group for Yakushima Sea Turtles,' the precursor of the non-profit organization (“NPO”) Yakushima Umigame-kan, was founded in April 1985 in Nagata, the north-western part of Yakushima, to protect the most beautiful beaches of Yakushima.
During this time, the sand from the beach was excavated to be used as building materials. The excavation continued despite the fact that the sand had decreased to almost half to a quarter of what was there in the 1960s.
The main idea of the NPO is to preserve the beaches where the turtles come to lay eggs by generating jobs related to sea turtles through the following activities:

　▼　Ecological investigation of sea turtles

We aim to help protect the turtles by conducting research on the behavior of the sea turtles which is still unknown.
Yakushima is the largest nesting area for loggerhead turtles in the Northern Pacific Region, attracting about 50% of all loggerhead turtles that come to lay eggs in Japan; thus, the research and monitoring in Yakushima is expected to gather much attention worldwide.


Before departing for ecological investigation	Attachment of tag

Measurement of shell size	Loggerhead turtle with tag attached
Individual identification is important. We attach the Multi-flex P tags to left front and left rear flippers and inject the internal PIT tags into left front flipper. We also measure the size and record characteristics of carapace, and measure body weight if possible. Tags are necessary for understanding things such as the number of times sea turtles lay eggs, the migration route, years it takes for sea turtles to return to the beach, lifespan, and so on. Research by tags revealed that, in Yakushima, most loggerhead turtles lay eggs three times on average per one nesting season although it was once recorded that one individual laid eggs as many as six times. Research by tags also revealed that sea turtles come back to Yakushima　every two to three years and that most loggerhead turtles migrate around the East China Sea. There were two loggerhead turtles that migrated as far as Philippines, one of which was found in the Nagata-hama of Yakushima following year.

Research on hatching
We research hatching by excavating the nest approximately 3 to10 days after the hatchlings emerge from the nest. We monitor the number of hatched and unhatched eggs to calculate the success rate for hatching. Hatching rate and emerging rate vary depending on the seasonal change of the given year. Dead hatchlings as well as eggs eaten by maggot, ghost crab, beetle larva, white ant and so on are often observed. Recently, the number of dead hatchings and embryos stepped by visitors has been increasing, resulting in the higher hatching and emerging rates at places without visitors than those with visitors. In general, the hatching and emerging rates are higher after mid-August.

　▼　Conservation of sea turtles

Researching the behavior of sea turtles can accompany the rescue of sea turtles, the support for laying eggs, or the relocation of eggs. Since sea turtles generally live in the ocean and only return to the beach for nesting, they are not used to life on the land. In some cases, they may get stuck in wave-dissipating blocks or rocks, or fall from sea wall. We rescue such turtles, assist sea turtles with deformed or disabled flipper in laying eggs, and relocate eggs which may be washed away by typhoon and high tides to the safer place. Although these activities are helpful in increasing the number of sea turtles, protecting the habitat is the most important for sea turtles to become self-sustaining.


Setting up a fence to protect the nests from trampling	Protecting the eggs before being washed away

Protecting the eggs before being tramped on	Relocating the rescued eggs

Protecting the baby turtles before dying from trampling
Sea turtles decide the nesting place considering the geography of beach or artificial factors. If sea turtles lay eggs in areas which can be affected by typhoons, high tides, or visitors, eggs are relocated to safer places such as the upper section of the beach and the area surrounded by the protection rope installed during the nesting/hatching season. Relocating eggs with embryo requires caution because embryo dies when placed upside down; to avoid this, we mark the top of the eggs before relocation. The most important thing, however, is to preserve the beach where eggs can hatch without relocation.

Rescuing a turtle stuck in a rock
Sea turtles that landed on the beach move around to find a suitable place for nesting. In some cases, they may get stuck in wave-dissipating blocks or rocks; in other cases, they may fall from breakwater. Sea turtles exposed to less moist environment may dehydrate due to sun light or get fever, which eventually causes death. Therefore, it is necessary to rescue these turtles as promptly as possible. However, rescuing sea turtles that weight almost 100 kg is not easy and requires a lot of manpower.

　▼　Protection and enlightenment of the environment


Study session with children on the beach	Study session with children at Umigame-Kan

Planting pine trees that disappeared from the beach	Maintenance of the tree-line to block light

Releasing young turtles raised till one year of age	Beach cleaning

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