September 12, 2024

June 2024 "Kuroshima Research Institute Training Activities" Participation Report

Our company conducts training activities to allow our group employees to experience the activities of the Kuroshima Research Institute and the environment of Kuroshima firsthand. This year, the training took place in June 2024 for three nights and four days. This report features a participant's account

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== ... As there are no rivers, water is supplied from Iriomote Island through an undersea pipeline. As there are no rivers, the incidence of malaria is lower than on islands such as Iriomote Island, which is why Kuroshima has a long history of settlement.

<Confirming Egg-laying the Day Before>
At Nishinohama Beach, Kuroshima Research Institute trainee Maeda and Kuroshima Research Institute chief trainee Kameda dug and confirmed the green sea turtle egg-laying site that they had confirmed the night before. The approximate location was known, and even though Kameda poked a thin metal rod into the sand to search for areas where the turtles had hardened their feet, it still took just under an hour from the time they started digging to the time they found the eggs.
Immediately after egg-laying, the eggs become soft and concave in order to withstand the impact of being laid, but they gradually harden. Also, since the position of the embryo is fixed more than a day after egg-laying, apparently turning the eggs upside down will kill the embryo and prevent it from hatching.

<Coast Cleanup>
A cleanup was conducted at Nishinohama Beach. Styrofoam, plastic bottles with Chinese and Korean labels, and various sizes of fishing gear were scattered around.
Because Kuroshima Island is unable to dispose of the waste, the waste was packed into flexible container bags, brought to the port, and transported to Ishigaki Island. Although five or six flexible container bags were used, only about one-third of Nishinohama Beach was cleaned.
Even the plastic bottles that washed ashore cannot be disposed of as recyclable waste; they are classified as non-burnable waste. The components of imported plastic bottles are unknown, and they contain sand and salt, making them difficult to burn and convert into energy.
Furthermore, the Styrofoam and fishing gear were noticeably degraded by ultraviolet rays. However, since it seems difficult to completely remove the finely shredded Styrofoam from the beach
, we felt the need for regular beach cleanups.

<Feeding experience at a farm>
Kuroshima has a population of 221 people and raises 2,800 beef cattle. Calves are sold to fattening businesses on Ishigaki Island and outside the prefecture for around 500,000 yen each.
The island also has a large auction site where auctions are held once every two months. The farm where we had the feeding experience this time apparently auctions around 10 to 15 cattle each time.
The farms on the island mainly raise cows and calves, and since cows give birth to calves through artificial insemination, bulls are sold when they are still calves. Just like humans, cows are susceptible to heatstroke, so measures such as spraying mist are taken on the farm.

<Confirming Egg Laying>
After dinner at the inn, we walked along the west beach under the guidance of Mr. Nakanishi of the Kuroshima Research Institute, searching for sea turtles coming ashore and laying eggs.
About five minutes into our walk, we discovered tracks extending from the sea. It's said that the type of sea turtle can be determined by the traces of landing. The one we found this time had alternating paw prints, indicating it was a hawksbill turtle, which is smaller than a green turtle. It's also said that different species of sea turtle have distinctive nesting locations; hawksbill turtles tend to be found in the bushes at the back of the beach, while green turtles are often found just in front of the bushes at the back of the beach. Since it took about an hour from laying eggs to filling up the hole, it's estimated that it took about two hours from landing to returning to the sea.
The next day, Mr. Nakanishi told us that the tag on the turtle's foot identified it as a hawksbill turtle that had been tagged and released 20 years ago.

<Tagging and Release>
The weight, carapace length, and carapace width of the green turtles at the Kuroshima Research Station were measured, and two tagging tags were attached to their legs before they were released from a beach near the port. This survey allows us to understand the growth of the sea turtles, how long they have been growing, how far they have migrated, and whether, like the hawksbill turtle seen the night before, they are living in the sea where they grew up.

<Visit to the Tsushima Maru Memorial Museum>
On our final day, we traveled to Naha and visited the Tsushima Maru Memorial Museum.
The Tsushima Maru was a cargo ship operated by Nippon Yusen Kaisha and requisitioned by the Japanese Army during the Pacific War. En route from Naha to Nagasaki as an evacuation ship carrying approximately 1,700 civilians and children, it was torpedoed by the U.S. Navy submarine USS Bowfin on August 22, 1944, and sank, killing many, including the pilot. The exact number of passengers, dead, and survivors is unknown. One factor contributing to the uncertainty is that Okinawa became a battlefield after the Tsushima Maru incident, resulting in the loss of homes and personal belongings, and the loss of family members. The memorial museum displayed exhibits detailing the events leading up to the sinking, U.S. military records, and portraits of the victims.

[Impressions]
The habitat ranges of sea turtles vary by species, but this has been changing due to the recent rise in sea temperatures. Previously, the Yaeyama Islands were the northern limit for hawksbill turtles, and the Yaeyama Islands were the southern limit for loggerhead turtles. However, gradually, hawksbill turtles can now be seen further north than the Yaeyama Islands, while the number of loggerhead turtles seen in the Yaeyama Islands is decreasing. Global warming is affecting not only abnormal weather but also ecosystem distribution, and we learned that simply maintaining sandy beaches where sea turtles can lay their eggs is not enough. Kuroshima also has almost no lights, and has been certified as Japan's first starry sky conservation area. Not only were there so many stars that it was virtually impossible to distinguish the constellations, but we were also able to see shooting stars and the StarLink Train with the naked eye.
I was able to experience things I probably would never have had on my own, such as watching sea turtles lay their eggs, the crystal clear waters of Kuroshima, snorkeling on the Akari and seeing the coral reefs, and starry skies like those in a planetarium. Participating in this training was a great opportunity to broaden my knowledge, and I'm grateful to the Kuroshima Laboratory for their full support in providing this valuable experience. I hope that by continuing to clean up the coast and providing regular support to the Kuroshima Laboratory, KYK can give back to the ocean, and that each employee will become more aware of global warming and GHG reduction, leading to thinking about the direction KYK should take.

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