Phantom islands raise doubts about territorial boundaries

Among the many remote islands that serve as reference points to determine Japan’s territorial waters and exclusive economic zone, there are many whose existence cannot be confirmed, The Yomiuri Shimbun has learned.

A fisherman who has been working on the waters off Kagoshima Prefecture for three decades has been left puzzled by a certain island that appears on a government chart.

“I’ve been passing through [those waters] for years and there’s no island or anything,” he said.

The case of the Kagoshima island shows the possibility of inaccuracies in the maps and charts used to prove the presence of border islands. This indicates that Japan’s territorial waters could be narrower, and shows the difficulties the nation faces in surveying and certifying the nearly 500 remote islands serving as its border.

In 2007, the government enacted the Basic Law on Ocean Policy and other laws for the conservation of remote islands, saying they play an important role in the securing of marine resources. By 2017, the Cabinet Office had officially named or carried out procedures for nationalizing 60 remote inhabited islands and 424 remote uninhabited islands — including the Senkaku Islands in Okinawa Prefecture, where China has repeatedly intruded into Japanese territorial waters.

However, the government could not confirm the location of some of the islands when it conducted on-site surveys and checked satellite images from that year.

Ice floes and waves are believed to have eroded what was left of the island of Esanbe Hanakita Kojima off the coast of Sarufutsu, Hokkaido Prefecture. There are other similar islands, but the Cabinet Office would only say it is in the process of confirming them, without specifying a reason.

According to sources, there is no island where one called Suzume Kita-Kojima is marked on maps and marine charts off the coast of Minami-Satsuma, Kagoshima Prefecture.

Suzume Kita-Kojima is estimated to have an area of about 35 square meters, but an aerial survey conducted by The Yomiuri Shimbun found only a wide expanse of sea at the location. The Cabinet Office certified the island based on maps by the Geospatial Information Authority of Japan and marine charts by the Japan Coast Guard (JCG), but has not conducted an on-site survey.

According to the authority, the island was included on its 2014 map, which is understood to be based on marine charts. The JCG says the island was marked on its charts in 1985. A JCG official acknowledged that there may not be an island at the marked location.

“The marine chart was drawn from a survey using an airplane. It is possible that the location of an island might have been shifted during the drawing process from its actual location,” the official explained.

According to the JCG, the charts are supposed to highlight the presence of islands to prevent accidents by ships. However, it is feared that the territorial waters could narrow by more than 0.5 square kilometers.

A Cabinet Office source said, “Because of the great distances, there are many islands that will take time to investigate,” adding, “The certification procedure is appropriate and on-site inspections are progressing. If any discrepancies are found, we want them to be corrected.”

Territorial waters extend up to about 22 kilometers from a country’s coastline, while the EEZ extends up to about 370 kilometers. Territorial waters are under the sovereignty of the state, and countries have priority rights for fishing and drilling for natural resources in their EEZs.