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could be determined by scientific means must be regarded as an economical 

 advantage of considerable importance. The rational management of the fishery 

 in any district is only possible when the fluctuations of the yield, the chances 

 appertaining to the special branch in question, are known as accurately as 

 possible beforehand. This knowledge must, however, rest on a scientific basis, 

 which is only to be obtained by continued and thorough study of the subject. 

 In order to attain the object in view, it was highly necessary that such in- 

 vestigations should extend over the whole area of distribution of each individual 

 fish of economical importance; which could only be done by means of inter- 

 national co-operation. 



Any rational exploitation of the sea must, as stated in the Christiania 

 programme of 1901, rest as far as possible upon a scientific basis. For this 

 purpose, international co-operation is especially suitable. And the main object 

 thereafter to be kept in view is the protection, and if possible the practical 

 improvement of the fishing industry by means of international fishery legislation. 



Scientific work on the basis of a programme drawn up by mutual 

 agreement, and carried out by uniform methods was, then, the essential idea 

 which should be kept in view. A detailed plan of work was first fixed upon, 

 determining the tasks which all the co-operating countries undertook to carry 

 out simultaneously, as well as those which it was desirable, though not obliga- 

 tory to execute. 



It was upon the basis of this programme that the International Invest- 

 igation of the Sea came into being. In order, however, to arrive as early as 

 possible at practical results of real value to the fishing industry, it became 

 necessary, at any rate in part, to concentrate the common work upon certain 

 main problems. Two such special problems were immediately and energetically 

 attacked. If it is asked what practical results have hitherto been obtained by 

 the international co-operation, it is necessary first of all to explain what has 

 been contributed to the solution of these problems. 



The first question was, as might be expected, that of the migration of 

 fishes, the investigations on this subject being especially concerned with two, 

 viz: — the cod and the herring. Soon, however, the investigations were so 

 extended, especially by means of marking experiments, as to embrace other 

 fish, especially the plaice and the eel; as to these more will be said later. The 



