There are probably various other differences which might be 

 citedj but, if we consider the origin of these differences,, they 

 are, after allj, based on the characteristics of thu resource which 

 each of these fisheries has as its objoct. The essential cha= 

 racteristics of the resource aroj in the final analysis^ ascnbable 

 to the environment 5 that is, to differences in the character of the 

 waters and the adaptability of the fishes. 



First of all let us add some considerations relating to the 

 first point of difference, that iSj, the difference in the type of 

 enterprises 



The surface fishes are possessed of great mobility and migrate 

 widely in the oceanso Various explanations of the causes and 

 courses of these migrations are put forward, but, because of the 

 presence of numerous elements of difficulty in the study of these 

 phenomena, knowledge which might contribute directly and appropriately 

 to the operation of the fishery is as yet almost totally lackingo 

 For this reason it is difficult to forecast the results of fishing 

 without actually going to the fishing grounds and operating there. 

 In the case of the bottom fisheries such forecasts can already be 

 made with some accuracyo In other words, the surface fisheries 

 can be said to be inferior to the bottom fisheries in stability 

 or susceptibility of planningo This low degree of operational 

 planability and the low catch efficiency described below have pro- 

 bably been the most important causes operating to curb the desires 

 of capitalists to invest in these fisheries in the pasto Besides 

 these reasons, the surface fisheries do not require a great deal of 

 material as compared with the bottom fisheries, and so it is com- 

 paratively easy to enter such a fishery with small capitals This 

 has probably been a powerful cause for the prevalence of individual 

 enterprise in the fishery^ 



In recent years tuna longline fishing grounds, principally for 

 yellowfin, have been developed in tropical waters, the planability 

 and stability of the fishery have been greatly increased, and the 

 advance of big capital into this field has been brought abouto This 

 is the so-called mothership-type tuna fishery. 



The initiation and development of the mothership-type tuna 

 fishery before the second World War cannot, however, be fairly 

 ascribed simply to the above-mentioned improved planability and 

 stabilization of this fisheryo It is an undeniable fact that it 

 reflected the economic conditions which obtained in Japan at that 

 timoo That is, the strengthening of controls on the use of materials 

 employed in the fishery, particularly fuel, made single vessel 

 operations remarkably difficult, and mothership-type tuna fishing 

 was devised as a measure for overcoming these circumstanceso 



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