During the pre-war period the main industries of the Ogasawara Islands were agriculture and fisheries. In agriculture, tropical plants and useful plants from the Japanese mainland were introduced around 1877, and indigo was also cultivated, but without being able to adapt to the conditions it soon declined. Thereafter the cultivation of sweet potatoes and bananas was also attempted, but a collapse in sugar prices and the impact of disease and pests caused these crops to decline also. (Ref. 1) From the Showa period (mid 1920s) onwards, taking advantage of the subtropical nature of the climate, the cultivation of tomatoes, cucumbers, and pumpkins flourished, especially in winter, with produce being shipped to the mainland. (Ref. 1, 2) 

Measures to develop the fisheries industry began in earnest from the end of the Meiji period (early 20th century), and together with agriculture fisheries became one of the major industries on the islands. Fishing for tuna, mackerel scad, Spanish mackerel, green turtles, and whales was conducted. (Ref. 1, 2) 

There were whale processing plants on Anijima and Hahajima, and ice production plants on Chichijima and Hahajima. Also produced were bonito and horse mackerel flakes, and sugar was also grown and processed on the islands (brown sugar, jaggery). Alcohol (shochu) was also distilled, and various snacks and sweets were manufactured (candy, rice crackers, manju buns). (Ref. 2)

Ref. 1: Nanpo Doho Engokai, Ogasawara no genkyo: Fu Ogasawara henkan no kiroku (Current Situation of Ogasawara: Record of the Reversion of Ogasawara), 1969, pp. 37-41. 

Ref. 2: Tokyo Metropolitan Ogasawara Branch Office, Kannai Gaiyo (Overview of the Jurisdiction), 2019 ed., p. 79.