MotherBhip-type tuna fishing was tested by the late Technician Mokuichi Shimoda in 

 1932 and 1933. Earlier, beginning in 1930, the Fisheries Institute training vessel Hakuyo Maru 

 had practiced tuna longline fishing in various regions of the South. As the exercises of the 

 HakuyC Maru could be considered a sort of mothership-type operation, the mothership experi- 

 ments of Technician Shimoda were probably inspired by the Hakuyo Maru's results. 



Technician Shimoda's mothership-type tuna fishing was a system in which the 1, 537- 

 ton Haruna Maru was employed as a mothership with two 9.6-meter, 45-horsepower boats and 

 six 7.8-meter, b-horsepower boats as catchers. The catcher boats were carried aboard the 

 mothership, lowered each time they fished, and brought back aboard when the fishing was 

 finished. As the mothership had refrigeration equipment and canning machinery and the catch 

 wais processed aboard the ship, it might be nnore appropriately called a connbination floating 

 cannery and mothership rather than a pure mothership-type vessel. 



With this system the Haruna Maru operated experimentally off the Indian Ocean coast 

 of Sumatra, around the Nicobar Islands, and in the vicinity of Timor. On the basis of its re- 

 sults it was concluded that mothership-type tuna fishing offered good possibilities. 



However, to cite the weak points of the Haruna Maru's system, 



1. A little rough weather makes it difficult to lower and bring aboard the fishing 



boats. 



2. As the fishing boats are small, their activity is greatly limited by the weather. 



3. Even in calm weather the fishing boats must always operate within sight of the 

 mothership because they are unable to navigate on their own account. 



4. No scouting vessels were employed as they are in the case of a whaling mother- 

 ship. 



Even in the so-called doldrums of low latitude seas the northern and southern mon- 

 soons sometimes blow with considerable force. Furthermore, sudden winds accompanied by 

 fierce squalls often spring up maicing the use of portable catcher boats dajigerous ajid interfering 

 greatly with their operation. 



While the practicability of mothership-type tuna fishing was being argued in Japan, 

 an early start was made in Formosa. At the end of 1940 the Tobu Suisan Company, a subsi- 

 diary of the Nippon Suisan Company, with the assistance of the Formosa Government-General, 

 planned such an operation and began to put the plan into execution at the beginning of 1941. 



The Tobu Suisan Company employed as motherships the Oi Maru 2ind the Kitakami 

 Maru, both of 500 tons, based at Takao. Six catcher boats were assigned to them. As these 

 were fishing vessels of the 60 to 80-ton class, they were of course capable of navigating for 

 themselves. One of the two motherships was on the fishing grounds at all times, directing the 

 fishing fleet and freezing the catch aboard in the form of fillets. A mothership would remain 

 with the catchers on the fishing grounds for about one month, during which t^me the other 

 mothership was carrying the catch to the base, and loading provisions, fuel, bait, and other 

 necessary materials to be carried to the fishing grounds. On arriving on the fishing grounds, 

 this ship would take over direction of the fleet and the other mothership would head for the base. 



When it was attempted to put this system into actual practice, it became painfully 

 obvious that the catcher boats were too small. If they were unable to utilize the lee of an island, 

 the transfer of catch and supplies at sea presented various difficulties and obstacles. The 

 welfare of the catcher boat crews operating at sea over long periods also was probably a major 

 problem. 



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