IHTEODUCTIOH 



I}urlng the laet several decades thn tunas have assumed a position of major Importance 

 In commerolal fisheries throughout the world. Much Interest now centers in this group 

 because of the tremendous demand In many countries for canned tuna products either for 

 Indigenous consumption or for thnlr value as export items. Important fisheries consequently 

 have been developed in North American and northern European countries. In Japan and in the 

 Mediterranean region» however, not only are the tunas of considerable present-day Importance 

 but they have been taken since ancient times and have been among the most esteemed of all 

 fish. 



Japan is admirably situated for exploiting the lar^e oceanic species, many of which per- 

 form wide migrations and enter its coastal and offshore waters at some time during their life 

 histories. Two Island chains, the Philipplne-Byukyu and the KarianaE-Bonin-Izu, converge 

 into the southern half of Japan (figure l). These island groups, with shallow water and 

 adequate food present In their immediate vicinity, provide a series of stepping stones for 

 (be northward migration of large fish. In Japanese waters, the tunas are able to find an 

 abundance of the small fish and pelagic crustaceans that conpriee the bulk of their diet. 



Other features of the weutern i'aciflc Ocean are also responsible for directing the 

 far-ranging tunas into Jfipaneee sea regions. Since the tunas are primarily warm water forms, 

 they enter Japanese waters during the summer months because of the widening Influence of 

 the North Equatorial Current and the consequent progressive warming of the waters along the 

 Japan coasts (compare FiLn-'-res 2 and 3). The areae through which the currents (the Kuroshio 

 OS the Pacific side and the Tsushima in the Sea of Japan) flow have been the major regions 

 for tuna operations. The fishing season for the most important commercial species reaches 

 its peak during the late summer in the sea regions east of northern Honshu. Current and 

 temperature are important in determlnli^ the seaoonal occurrence and abundance of the tunas i 

 and any variation froir. the normal profoundly affects the fisheries for these species. 



Numerous references to the tunas as articles of diet occur in Japanese claseical litera- 

 ture. These indicate the ancient status of the fisheries, but, unfortunately, few hints in 

 the old writings show what the earliest fishing methods were. Authorities assume that the 

 most primitive fishing technique was hook and line, spears, or traps set in places ordinar- 

 ily visited by those tunas that enter shallow coastal waters during their migrations. 



Prior to and during most of the Meiji Sra (1867-1912), rowboats (tskoglbune) or small 

 ■ailing vessels (shohansen) were used for tuna fishing. Thus, operations were necessarily 

 confined to coastal waters. The introduction of motor-driven vessels made it possible to 

 develop the pelagic offshore fisheries. In 1906 the first skipjack vessel equipped with 

 an engine was operated successfully, and the following year an engine was installed in a 

 tuna long line boat. 1/ Fishing in the Bonln Islands by vessels operating directly from 

 a Japanese port began in 1909. By 1910-11 all vessels operating in the offshore waters were 

 equipped with engines. Larger boate were constructed and practical fishing operations be- 

 came possible at increaKingly greet distances from land. 



At first the skipjack g/, which was in great demand by the Japanese housewife for use 

 ss a ccndiment , was the only species exploited by the offshore fishermen to any great extent. 

 The skipjack remained the most important member of the group of large pelagic species, but, 

 following the first shipment of canned albacore from Japan to New lork in 1929, an increasing 

 demand arose for tuna products to supply a growing export market. In later years the export 

 of canned and frozen tuna products in large quantities became increasingly necessary to the 

 Japanese Qovernment because of its efforts to establish credits for world trade* 



1/ See section on Tuna Fishing Vessels , for explanation of types of vessels. 



8/ This species ( Katsuwonus pelamie) has a worldwide distribution and is known by a variety 

 of vernacular names, for example, bonito, osaanic bonlto, striped-bellied bonito, striped 

 tuna, and skipjack. Snglish translations of Japanese fisiiery papers refer to the species 

 as the bonito. However, skipjack is this preferred name in this paper, because this term 

 is used in United States statistical reports. 



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P-6307 



