In 1925i as a result of eurveys made 1/ several Investigators, a ak-ipjaoK vessel 

 was sent directly from a Japanese port Into the Indo-?aclflc region. The amount of skip- 

 jack taken 'by euch (derations and landed at Japanese ports was extremely small ty comparison 

 with that in home waters. Kevertheless, these operations were significant in that boats 

 fishing that region could otserve and report to Japan the abundance and the types of fleh 

 present. Thus, when the Japanose chjee to expand their pel=i(.;lc flsMerles tlisy could turn 

 their attention to an area which had soae Indication of being productive although located 

 at a distance from home porta. 



The next ad7ance in the fisheries came with the opening of foreign jiarkets for tuna 

 products in 1929. In succeeding years albacore. either frozen (Table 10) or as canned white- 

 meat tuna (Table 12), became the dominant oxport item in the fisheries. Smaller arajunts of 

 frozen skipjack and sworrifish and an undetermined but minor quantity of canned skipjack were 

 also exported. The United States was the chief importer of these products, buying all the 

 frozen albacore, swordfish, and skipjack and well over 50 percent of the canned white-meat 

 tina exported by the Japanese. Canned skipjack was sent to Ael?.tic and European countries 

 during 1933 and 1934. The market for this item disappeared, and in the years following, 

 white-meat tuna was the solo exportable canned product. Since the albacore was in sucti great 

 deraand fishermen now began to take the species in lar^e numbers from the areas close to the 

 Japanese mainland and also surveyed and located extensive new fishing grounds, in the rai^- 

 Paciflc. The surveys were extended into the southwest Pacific region, mainly between 19?1 

 and 1934, but here it was shown that th» yellowfin tuna, not th«. albacore, was thf; dominant 

 commercial species. 



A boost in the requirements of food for the Chinese-Japanese war effort Intenslfiec 

 tuna fishing operations, with resulting Increesed catches from 19.''5 to 1940. A sustained 

 increase during this period can be noted for the skipjack. This was almost completely the 

 result of Increased offshore operations. The behavior of the fisheries for the other species 

 (taken chiefly by long line) is not quite so clear. The coastal catch of other tunas (Figure 

 22) showed Increased yields for most of these years and almost approached the yield attained 

 by offshore operations. This may be attributed to Intensive fishin^; effort taking advantage 

 of the fact that certain species, such as the black tuna, appear In Japanese waters period- 

 ically in great abundance (Table 8), emd cause extreme annual fluctuations in catch. The 

 period of survey in the Mandated Islands had shown that the yellowfin tuna could support a 

 thriving fishery. Bxploitatlon of the area, despite Inadequate supnMes of fuel and the 

 drafting of large fishing vesBels by the Japanese navy, was under wy by 1938. Lonp; line 

 vessels obtained a sizable catch, cunsldering the Bmall nufliber of voyftges th-it \ ire ma-Je to 

 southern waters. This catch was landed at Japanete home ports and is included in the total 

 catch of tunas. The boats used for the operations In the southern regions could not be used 

 in Japanese waters; consequently the effect on the total tuna production (excluding skipjack) 

 wn* not marked. 



As the bulk of the catch was taken in the offshore waters, the tuna fisheries were 

 adversely affected soon after the beginning of World War II (Figure 22). Operations were vir- 

 tually suspended by the end of the war except for the small nunber carried on mostly in coastal 

 waters. Two-thirds of the fishing fleet (especially vessels of larger size) was sunV, and 

 many experienced fishermen lost their lives. Rebuilding of the postwar fleet has been rapid 

 (see p 34 and Tables 5 and 6), and by 1948 the number of vessels will exceed those in oper- 

 ation prior tu 1941. According to Japanese ostimates, the catch of tuna In 1948 will approx- 

 imate the hi«5h levels attained during '-ho prow>ir years in those areas now authorized for Japa- 

 nese fishing operationst providing flehin^ efficiency and other conditions are equal (cuig>are 

 Tables 8 and 13). The Japanese should be able to attain 90 percent of their total prewar 

 tuna catch, since their prewar operations were largely confined to waters within the present 

 authorized areas (compare ?igures 6, B, 10, 12, and 15). Except for the development of a 

 large winter Industry for the gJ.bacore in the mid-Pacific and the initial exploitation of the 

 South Seas yellowfin tuna fisheries, the tuna fisheries were operated on a commercial basis 

 In the waters nearer to the Japanese homeland. Experienced Japanese fishermen an<l fishery 

 biologists state that the prewar exploitation of tuna had apparently attained its sustainid 

 peak in all areas with the exception of the southern regions. 



During the decade prior to World War II the Increasing importance of the tuna fish- 

 erles, especially for the purpose of obtaining export itoms, led to a much greater apprecia;- 

 tlon of the necessity for an accurate picture of the industry. The Tokyo Central Fisheries 



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