HYDROGRAPHICAL INVESTIGATIONS 209 



Norwegian depression, and from the south along 

 the continental coasts into the Skagerack. 



These results of the international survey of 1893 

 showed, then, that the prolific fishing grounds of 

 the North Sea were subject to important seasonal 

 variations in respect of the nature and source of 

 the water covering them, and of the organisms 

 which composed the plankton inhabiting the sea. 

 But the problem was one of very great magnitude 

 and importance, and it was seen that, if it were to 

 be investigated on a sufficient scale, a wider area 

 would have to be taken into account, and a greater 

 number of exploring vessels would be required. 

 International co-operation was the only means by 

 which the work could be done, and several attempts 

 were made to secure this on the part of the States 

 interested in the fisheries of the North Sea. There 

 were other important reasons which made inter- 

 national co-operation in fisheries research very 

 desirable. The agitation for some restriction on 

 the capture of small flat fish in the North Sea had 

 assumed its present form. The grounds on which 

 these small fishes are captured are outside the 

 territorial limits of any State ; and while it is within 

 the power of any one of the governments concerned 

 to impose restrictions on the area exploited, or the 

 methods adopted, by its own vessels^ international 

 agreement only could affect all the vessels catching 

 these small fishes. A further argument in favour 

 of international agreement is that this might lead 



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