lie, Fisheries 



The fisheries are carried on by skilfully utilizing the habits of 

 these fishes. In offshore waters the fishing is chiefly done with long- 

 lines, but drift-net fishing is also carried on at timeSo 



In longline fishing, as shown In Figure 4-j the gear is linked to- 

 gether and suspended from the surface of the water. Fishing grounds are 

 in the waters adjacent to Japan proper, in Formosan waters, and in the 

 South Seas Government-General, of course, but the East Philippines Sea, 

 the South China Sea, the Sulu Sea, and the Celebes Sea also have already 

 become operating areas. Aside from these waters the extensive warm seas 

 of the Pacific and Indian Oceans are expected to afford fishing grounds, 

 and some investigations are already being made in those areas„ In the area 

 between 20° north latitude and 15° south latitude and 90° and 180° east 

 longitude the extent of the fishing grounds already surveyed actually 

 amounts to three and one-half million square miles. Furthermore, it is 

 extremely gratifying that these surveys have all been made by our country. 

 As far as the tuna longline fishery is concerned, the seas of Greater 

 East Asia were already our fishing grounds even before the Great East 

 Asia War. 



When, as will be described below, the tuna move northward in the 

 spring and summer through the waters adjacent to Japan proper, they corae 

 in extremely close to shore and then a fishery with stationary gear is 

 carried on with the large set- nets which are placed everywhere along the 

 coasts. 



The spearfishes have in general the habit of swimming close to the 

 surface with a portion of their dorsal and caudal fins protruding from 

 the water under conditions where the current and the wind are running in 

 opposite directions and the surface of the sea shows whitecaps. Because 

 of this, in addition to the above-mentioned fishery, a special harpoon 

 fishery is carried on. In this fishery the gear used is a harpoon, 'ifl/hen 

 a fish is sighted swimming at the surface, Ihe boat gives chase to it and, 

 arriving at close range, the fish is captured by throwing the harpoon at 

 it in this extremely thrilling fishery. 



In addition to the above a trolling fishery, in which an artifiqial 

 bait is pulled astern of the boat, and a pole and line fishery, like that 

 for skipjack, are carried on, but they are on a small scale,. 



This is not related to the fishery, but it is interesting to see 

 how the various species act differently when they are caught on the hooks 

 of a longline. The catch of the longline fishery is largely tunas, spear- 

 fishes, and sharks, fflien tuna are hooked they have the habit of making 

 one very deep dive. In the case of a large black tuna the fish will drag 

 two or three glass ball floats of about 30 cm diameter down into the water. 

 In extreme cases they dive so deep that glass floats with a thickness of 

 1 cm are occasionally broken by the water pressure. 



The spearfishes, on the other hand, leap several times on the surface 

 and then run about horizontally, causing trouble by entangling the 



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