32 MANAGEMENT OF HIGH SEAS FISHERIES 



different from those in the United States and Canada. They indi- 

 cated that some of the most noticeable points of difference were that 

 in Japan "(a) a great emphasis has been placed on artificial propaga- 

 tion programs which up to now have been regarded and enforced as 

 indispensable conservation measures, as in Hokkaido; (b) very little 

 effort, if any, has been paid to improvement of environments detri- 

 mental to the natural spawning and survival of fry; and (c) no action 

 has ever been taken for directly controlling inshore catch of the 

 ascending fish so as to assure spawning escapement." "Lack of a 

 conservation policy which assures the spawning escapement by ad- 

 justing the fishing seasons and by providing the catch limits is doubt- 

 lessly the most serious defect which may undermine salmon resources 

 in this country (Japan)." 



A search of the records has revealed no fishery that the Japanese 

 have regulated for the purpose of maintaining yield. Restrictions of 

 their fisheries have been primarily for economic reasons, and controls 

 on fishing intensity seem to have as their priinary purpose an adjust- 

 ment of investment in gear and ships to the expected catch. Expand- 

 ing fleets have, as far as possible, been accommodated by expanding 

 into new regions. Their policy of expansion into new areas to main- 

 tain a growing fleet and to increase catches can work reasonably well 

 as long as there are new areas available, but the time is rapidly 

 coming to a close when new and imexploited fishing areas will be 

 available. 



The view has been expressed by several Japanese scientists, in 

 conversations, that the overfishing of one species of fish will result 

 in its replacement by another species which will maintain the total 

 yield at the same or even higher level. They have intimated that the 

 Japanese are interested in total yield of protein regardless of species, 

 and that therefore it is not necessary to conserve any one of the 

 principal species to produce the maximum amount of protein. How- 

 ever, this hypothesis does not seem to have been borne oiu in the 

 oceans, and logically could hardly be expected to occur under natural 

 conditions. Important exploited species of fish are nonnally domi- 

 nant species in their particular ecosystem. Their dominance must 

 have resulted from a greater rate of productivity, i.e., a combination 

 of all factors that could make them more successful than competing 

 species. Replacement by another species is possible if the dominant 

 species is fished very hard and very selectively, but it could not be 



