Senkaku Islands Ecosystem Threatened by Goats

By Chihiro Imamura / Yomiuri Shimbun Staff Writer

14:46 JST, April 10, 2023

NAHA — The unique ecosystem of the Senkaku Islands is deteriorating due to damage caused by goats, a development I witnessed during an environmental survey conducted by the city of Ishigaki, Okinawa Prefecture, to which the islands belong.

I accompanied the Jan. 30 offshore survey on the islands and surrounding waters amid tensions caused by China’s maritime expansion. I strongly felt that the central government must take effective measures to preserve the Senkakus as Japanese territory and waters.

Expanded rock exposure

The Senkaku Islands consist of uninhabited islands including Uotsuri, Kita-Kojima, Minami-Kojima, Kuba and Taisho. In April 2002, the government leased three of the islands, including the largest Uotsuri, from their owner, and banned people from landing there “for their peaceful and stable maintenance and management.”

This policy continued after the government acquired and nationalized the three islands in September 2012.

Accordingly, the city’s survey was conducted from the sea. It was the second of its kind, following one in January 2022.

The Shinsei Maru survey boat traveled to waters about 170 kilometers northwest of Ishigaki Island and then sailed clockwise around Uotsuri, Kita-Kojima, Minami-Kojima and other islands. The survey team included Ishigaki Mayor Yoshitaka Nakayama and other city officials. Yoshihiko Yamada, a professor at Tokai University and marine policy specialist, handled the survey.

In addition to conducting a marine survey that included examining the water quality, as was done in the previous inspection, the team flew a drone for the first time to take aerial images of Uotsuri Island to observe vegetation and other aspects of the island.

The drone was flown four times from the boat, which was about 2 kilometers offshore. It went as close to the coastline as possible without entering the airspace over the land, as requested by the Japan Coast Guard.

Even with just the naked eye, I could see that the south side of the island was not that green and that there were many bare rocks.

According to the survey team, the exposed rock surface had expanded by about 30% in just one year. Video analysis showed that the mountain surface was very dry although it was in the season with relatively high rain. The endangered Senkaku tsutsuji, an azalea species that blooms in purple at the time of year, was not seen.

Six rivers and waterfalls found in a survey conducted by the Tokyo metropolitan government just before the islands’ nationalization have almost disappeared.

“The island is beginning to lose the capacity to maintain its ecosystem,” said Yamada, who also participated in the metropolitan government’s survey.

Mayor seeks landing permit

The biggest problem is damage from feeding by non-native goats.

Goats eat leaves, stems and even the bark of plants, leading to concerns about the extensive impact on the environment, including reduced water storage capacity and damage to coral reefs caused by red soil runoff.

The goats on the island were bred from a mated pair brought there as food by a political group in 1978. More than 300 goats were found in the coastal area alone in 1993. At one time, their numbers are believed to have reached about 1,000.

An analysis done in the year 2000 of images taken by satellite showed that 13.6% of the island’s area was bare land due to feeding damage, and there were signs of vegetation decline throughout almost the entire island. Goats were also seen in video images taken in the latest survey.

Uotsuri Island has been called a “treasure house of nature,” being the habitat of more than 300 species of plants and animals, including about 10 endemic species such as the Senkaku mogura mole.

On-site research by Japanese scientists had already been conducted on the island even before World War II. Under U.S. rule after the war, the government of the Ryukyu Islands and Tetsuo Takara, a former president of the University of the Ryukyus, repeatedly conducted academic surveys of the local flora and fauna, compiling a wealth of records on its ecosystem.

The central government, however, stopped allowing landings and discontinued academic surveys after the last on-land survey in 2002.

The central government has used non-landing methods, including a survey by the Environment Ministry that analyzed the population of the endangered short-tailed albatross on Minami-Kojima Island based on satellite images taken in November 2020.

After the latest survey, the mayor requested the central government’s permission to land for a survey, stating that the goats need to be exterminated. The city is prepared to conduct biannual environmental surveys in the future.

Aboard the boat, I witnessed the current situation on the island and realized the need for taking measures based on the survey.

Ports needed for patrol vessels

Since Japan’s nationalization of the islands of Uotsuri, Kita-Kojima and Minami-Kojima, China has regularly made displays of force in the area, such as the intrusion of China Coast Guard vessels into Japan’s territorial waters. This has made it difficult for Japan to conduct even marine surveys.

In recent years, except on days with bad weather, Chinese vessels have been present in the contiguous zone, which is a 22-kilometer strip outside of Japan’s territorial waters. They have followed Japanese fishing vessels in Japan’s territorial waters, discouraging many fishermen from operating in the area.

On Jan. 30, the day the survey was conducted, CCG vessels appeared, intimidating four Japanese fishing boats operating in the territorial waters. One of the Chinese vessels sent wireless messages and attempted to approach the Shinsei Maru, which I was aboard.

Despite the presence of CCG vessels, JCG patrol vessels were always superior in number, calmly responding to China’s illegal activities.

During the survey, two or three patrol vessels immediately surrounded the Chinese vessel that came into view, not allowing it to approach. Around Uotsuri Island, a Japanese patrol vessel acted as the last line of defense, watching to prevent the Chinese side from coming ashore or landing on the island.

As China is increasing the size of its armed coast guard vessels, there is no guarantee that the JCG will remain superior.

In 2021, China put into force the Coast Guard Law that allows the use of weapons if China’s sovereignty is deemed to have been infringed. Last year, a large ship armed with a navy-level 76mm gun entered Japanese territorial waters.

Japan’s central government plans to strengthen coast guard capabilities, but Okinawa Island and the Sakishima Islands have poor port facilities for mooring an increased number of patrol vessels.

Naha Port does not have a dedicated quay for patrol vessels, so the central government will either rely on the U.S. military allowing Japan to use its Naha port or use available space in a civilian port.

When U.S. warships or civilian vessels call at these ports, the patrol vessels will need to be moved offshore. Many patrol vessels that have finished their duty of guarding the Senkakus will need to sail to Kagoshima Bay, which takes an extra half day to reach.

An official of the 11th Regional Coast Guard Headquarters in Naha said: “This will harm the morale of our personnel. I hope the situation will be improved as soon as possible.”