During the Second World War Japan's whaling was significantly limited to more familiar hunting grounds, such as the Bonin Islands, to provide meat and oil for domestic and military use. Whaling there was halted in March, 1945 when the islands were taken by US forces. By November 1945 the whaling stations received permission to reopen; however, most whaling ships had been commandeered by the Japanese navy, and by the end of the war the factory ships and most of the whale catchers had been sunk.[48][49]
General Douglas MacArthur encouraged the surrendered Japan to continue whaling in order to provide a cheap source of meat to starving people (and millions of dollars in oil for the USA and Europe).[50][51] The Japanese whaling industry quickly recovered as MacArthur authorized two tankers to be converted into factory ships, the Hashidate Maru and the Nisshin Maru. Whale catchers once again took blue whales, fins, humpbacks and sperm whales in the Antarctic and elsewhere.[50]
The first post-war expedition was overseen by a US naval officer, Lieutenant David McCracken, and observed by Australian Kenneth Coonan. Coonan expressed disapproval of McCracken in his reports of violated regulations and waste dumped over the side when the fleet began killing whales faster than they could be processed. McCracken even briefly joined in whaling with the Japanese crew of a whale catcher and detailed the trip in his 1948 book, Four Months on a Jap Whaler.[52]
The post-war recovery established whale meat as a nationwide food source for the first time. In 1947 whale meat made up over 50 percent of the meat consumed in Japan. The market significantly increased through commercial sale and public distribution. In 1954, the School Lunch Act also included whale meat in compulsory education (elementary and middle school) to improve the nutrition of Japanese children