Tuna Long Line Vessols for Taking Tlsh 'below Surface Levels: Species sach as the 

 altftcore. black tuna, yellowfln tana, big-eyed tuna, martin, and swordflsh are caught by 

 the long line technique, a method of fishing developed to a high degree of efficiency by 

 the Japanese. Long line vessels are called tuna boats by the Japanese and differ from skip- 

 Jack boat* in lacking the fishing platform, bait tanks, and the spray apparatus (Figure 14). 



During the past few years a combination pole and line ani long line vessel has been 

 constructed In Increasing numbers. These vessels pr£u:tlce pole and line surface fishing In 

 the summer and operate long lines for the tunas taken below surface level during the winter. 



In coastal waters vessels of small size, 5 to 20 tons, are used and generally are 

 built along the lines of the larger skipjack boats. 



The tuna fleets during the early decades of the 20th Century were composed largely 

 of vessels of small tonnage; only when the Japanese began to exploit the more distant fish- 

 ing grouitds during the 1930-40 decade did the emphasis shift to vessels of larger tonnage. 

 The operation of skipjack vessels of larger tonnage showed that they can obtain a larger 

 catch per ton of vessel (Table 4), can cruise at higher speeds more economlcsdly in a fishery 

 where speed is vital, and need to make fewer tripe since their hold capacity is larger than 

 that of smaller vessels. Sxperienced fishermen are now following the trend towards larger 

 Teseels, even for flehing close to the Japanese mainland. 



The most reliable data available on the tonnage of tuna fleets during the prewar 

 years was obtedned through a census made by the Bureau of Fisheries in 1940 (Table 5). 

 This tonnage operated for the most part in Je^amese home waters except for a small number 

 of vessels that were sent to the southern seas from the home ports of Misakl, Tsuro, and 

 Maroto. 



Curing the war much of the tuna fleet was taken over by the Japanese navy for coast 

 guard patrol and aircraft spotting. A considerable number of these vessels were sunk, leaving 

 the fleet at an estimated postwar strength of about 22,000 tons, coa^ared to the prewar ton- 

 nage of 52,555. The loss since World War II of major fishing areas (for exan^ile, salmon and 

 crab grounds in northern waters and trawling grounds in the Tellow Sea) caused many fishermen 

 to shift to other types of operations. Since many major tuna grounds are located within the 

 present authorized fishing areas (see Figures 6, 8, 10, 12, and 15), the postwar rebuilding 

 of the fleet has been hastened by the desire of the fishermen to exploit these fisheries. 



Data on the tuna fleet that will be available for fishing In 1948 have been compiled 

 by the Japanese Tuna Fishermen's ABsociatlon (Table 6). The trend toward building vessels of 

 larger size, for the reasons noted above, is evident. The increase in the number of vessels 

 for combined operations (pole and line and long line) is attributed to the shortage of gear. 



TUNA FISHING ttEAfi 

 1. general 



As stated previously, the tunas are primarily Inhabitants of the offshore pelagic 

 waters, although certain species, notably the skipjack and the black tuna, enter coastal 

 waters in considerable numbers. The schooling habits and the depths at «^ieh the tunas are 

 found differ not only by species but also within the species according to locality and season 

 of the year. Consequently fishing techniques are numerous and varied. Pole and line for sur- 

 face fishing and lon^; line for fishing below surface level are the most efficient and widely 

 used tuna gear. Other gear are limited in their application. 



3^* P-6307 



