Koga Tatsushiro's Development of the Senkaku Islands from 1884

Photograph of Uotsuri Island (photographer unknown) Provided by Naha City Museum of History.


(1) Overview of the Development of the Senkaku Islands

In 1879, Koga Tatsushiro went to Naha to start business in Okinawa, opening a branch office of his firm, Koga Shoten, on Ishigaki Island in 1882 and sending representatives to the Senkaku Islands in 1884. This information is given in the historical documents submitted by Koga when he was awarded a Blue Ribbon Medal of Honor in 1910. (Ref. 1)

In 1895, Koga rigged out a ship and investigated Kuba Island himself, receiving permission to develop the island in 1896, and sending 35 people, including fishermen and others, to the island in 1897. The group conducted a variety of activities, including harvesting yakogai sea snails, catching seabirds for their down or for taxidermy, collecting guano for use as fertilizer, and catching bonito and processing them into dried bonito flakes. These activities took place on Uotsuri Island, Kuba Island, Kitakojima Island, and Minamikojima Island. It is recorded that at its peak the total population reached 248 people in 99 dwellings. (Ref. 1)


(2) Koga's Activities

When full-scale development began in 1897, at first the main activity was catching albatrosses for their down. Koga Tatsushiro's petition for a lease on Kuba Island on June 10, 1895, was also centered on albatrosses. In the documents related to his being awarded a Blue Ribbon Medal of Honor, the amounts and value of the down gathered over the 11 years from 1897 to 1907 are given. In 1897, 10,000 kilograms of feathers were collected with a value of 6,800 yen, while in 1898 this greatly increased to 39,000 kilograms with a value of 30,550 yen, and in 1899 production peaked at 51,000 kilograms with a value of 42,500 yen. However, this dropped to 15,000 kilograms the following year as apparently the rapid increase in production from 1897 had led to a decline in resources. Also, during this time, the price of yakogai sea snails and other marine products had increased.

With the major decline in the albatross population, Koga Tatsushiro felt a sense of crisis about the sustainability of the down business. He consulted with Mitsukuri Kakichi, a professor and doctor of science at Tokyo Imperial University, who asked Miyajima Mikinosuke to conduct surveys. Kuroiwa Hisashi, a teacher at Okinawa Normal School, and Nomura Doan, the Yaeyama Islands leader, also joined the expeditions to each of the Senkaku Islands, conducted in May 1900 in an Osaka Shosen steamship, the Eiko Maru. The results of these expeditions were published in different volumes of Chigaku zasshi (Journal of Geography). (Ref. 2 and Ref. 3) Miyajima and Kuroiwa advised Koga to stop overhunting of birds and overfishing and to build houses for settlers, rainwater storage for Kuba Island (which had no freshwater resources), and harbors and roads. They also advised him to establish ways of processing sewage and to build sanitation facilities.

At this time, in his report in Chigaku zasshi, Kuroiwa named the group the "Senkaku Islands" for convenience's sake, as although the individual islands had names, there was no general term for the group of islands. This name later prevailed.

Following the conspicuous drop in down collection, in 1904 Koga began stuffing birds and in 1905 started production of dried bonito flakes. These became his main activities, particularly bonito flake production, as demonstrated by the rapid increase from the production of 8,000 kilograms of flakes with a value of 7,800 yen in 1905 to 41,000 kilograms with a value of 44,200 yen in 1906.

Koga Tatsushiro was awarded the Blue Ribbon Medal of Honor in 1909 in recognition of his achievements in developing the Senkaku Islands and his marine products business. It is likely that this was the peak of development on the islands. Photographs remain showing what "Koga Village" on Uotsuri Island and Kuba Island looked like.

Supplement 1: Picture showing the location of the Koga Shoten branch office on Ishigaki Island.
Supplement 2: Photograph of Koga Village at the time the islands were being developed.

Supplement 3: After development by Koga Tatsushiro.
In 1908, Tsuneto Noritaka conducted surveys of soil containing large amounts of phosphoric acid from bird droppings on Kitakojima Island, Minamikojima Island, and Kuba Island, testing its feasibility for use as fertilizer. Although he estimated that it had promise, this did not become an ongoing business. In 1918, Koga Tatsushirō died and his son Koga Zenji inherited his islands business. The activities gradually declined, though, and by the end of World War II in 1945, the Senkaku Islands were once again uninhabited. After World War II, there are reports of some traces of usage of Koga Village and semi-processing of dried bonito flakes for a time by people from Yonagunijima Island. In the 1960s, unauthorized activities by Taiwanese fishing boats became a problem. (Ref. 4)




Ref.1 : "Nihon teikoku hosho no ki: Koga Tatsushiro e ranju hosho kashi no ken, Utsushi" (Copy of Record of Medals Awarded by Imperial Japan: Award of Blue Ribbon Medal of Honor to Koga Tatsushiro), in Kobun zassan (Miscellaneous Official Records) Naikaku 4 (1909), National Archives of Japan.

Ref. 2: Kuroiwa Hisashi, "Senkaku Rettō tanken kiji" (Article on Exploration of the Senkaku Islands), in Chigaku zasshi (Journal of Geography) Compendium 12, Vol. 140 (1900).

Ref. 3: Miyajima Mikinosuke, "Okinawa kenka mujinto tankendan" (Story of Exploration of Uninhabited Islands in Okinawa Prefecture), in Chigaku zasshi (Journal of Geography) Compendium 12, Vol. 142 (1900).

Ref. 4: Senkaku Islands Document Material Compilation Association, "Senkaku Shoto kaiiki no gyogyo ni kansuru chosa hokoku: Okinawa ken ni okeru senzen-Nihon fukki (1972) no ugoki" (Survey Report Regarding Fishing in the Senkaku Islands Waters: Changes in Okinawa Prefecture From Before World War II Until Its Return to Japan in 1972) in Senkaku kenkyu (Senkaku Research) (2010). Published with assistance from a grant by the Nippon Foundation.