to waters east of Japan proper north as far as the Kuriles. 32/ East¬ 
ward vessels range 2,COO or more miles from their home ports. The 
"mingling region" lying along the line of convergence of the Kuroshio and 
Oyashio, which shifts according to seasons and other factors, was the most 
productive zone for ihe pelagic Scomhroids. The Japanese who had de¬ 
voted much scientific study to the natural conditions related to tuna 
and bonito were unable to predict areas of high productivity. 33 / 
The chief method used for deep-sea tuna fishing was line-trawling; 
this accounted for about 80 percent of the deep-sea tuna catch. Bonito 
was taken largely by rod and line. Purse-seine, drift netting and 
trolling were used but were distinctly of minor importance (Table 22). 
Line-trawling ( haenawa ) for tuna was similar to American line 
trawling except for differences in details. Wooden or glass floats 
were used instead of cork buoys and the line and ganging were kept 
aboard in baskets rather than in tubs. Approximately 100 " hachis " 
(baskets of trawl-line) were loaded for 50 - 100 ton vessels and 200 - 
300 baskets for the larger 150 - 160 ton vessels. For a vessel of 60 
or 60 tons 12 - 14 fishermen were needed; for the larger vessels 25 or 
more constituted the crew. The lines, baited with cuttlefish, mackerel 
or sardines, were-usually cast at dawn or in the evening. 34/ 
32/ Tuna which have a wider distribution are taken off Hokkaido and 
the Kuriles whereas bonito are not taken in quantity north of 42° in 
the deep seas. The species which accompany tuna and bonito are more 
diverse and abundant in the southern waters. 
33 / Office of Strategic Services typed report, "The Fishing Industry 
of Japan," June 1942 gives further details including maps, charts and 
tables concerning area of operation and seasonal changes. 
34/ Y. Sugiura, Suisan , 1939. 
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