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barrier is formed near the capes; i.e. capes of Nojima, Iro, Shionomisaki, Muroto and Ashizuri. It 
opens and shuts following the come and goes of atmospheric storms. 
Although the resonance mechanism is still unknown, the Kuroshio is suddenly acceleated to shed a 
cyclone from Giant-Cusps when an atmospheric storm attacks. An offlying-fence-net is identified 
with its outer edge, digital-like temperature gap across which barriers off the yellowtail excursion. 
3.4 Designing and settings of yellowtail fixed-net 
Design of yellowtail fixed nets has been progressively advanced to adjust its function to the 
local marine hydrodynamics. As shown in Figure 5(c), a standard design is mainly composed of 
three parts. The "fence-net” stretching about 1,000 meter offshore blocks the excursion of 
yellowtails riding on the Kyuu-Chou, guides the school to enter the "play-ground", and finally 
drives them into the "trap net", which the fishermen heave up. A noticeable feature is in the two 
types of entrance from fence-net to play-ground\ i.e. one-side-opened or both-sides-opened. 
Figure 5(d) shows a typical settings of fixed nets settings around the capes of Muroto and 
Ashizuri, senior sites of yellowtail fishery, which are interpreted on the airphotos taken by the 
Geographical Institute of Japan. Around the Cape-Muroto, the upstream fixed net is both-sides- 
opened, whereas the downstream ones are designed one-side opened to adjust to the Kyuu-Chou. 
Also around the Cape-Ashizuri, majority of fixed nets are installed downstream. The nets of 
one-side-opened are larger in size and stretche far about 1.5 km offshore. When a strong cyclonic 
eddy is shed, they would have a chance of big catch. When the Kyuu-Chou grows too strong, in 
exchange, they sometimes lose the nets. On the other hand, the both-sides-opened nets are rather 
small. Fence nets are installed within the topographic roughness, where the weak Maishio swirls 
rather turbulently and the fish comes from both sides of the nets. Although fishing is operated with 
lower risks, they barely hope the gamble-like high return. 
Figure 5. Schema of the yellowtail fixed net fishery on the Pacific-Ciast. (a) fishing grounds. 
(b) "Kyuu-Chou" system, (c) two types of designing, (d) settings, (partly from Uda (1941, 1984))