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The high percentage of very large and very old fish in the Barents Sea, and the 

 fact that these plaice reach there a far greater age than in any other waters, par- 

 ticularly the North Sea and the Baltic, clearly prove that the Barents Sea is a fishing 

 ground which is still in a virgin state, and has only been fished for some few years. 

 We can probably safely assert that this new fishing ground will, by intensive fishery, 

 very soon become exhausted, and probably in relatively less time than the Iceland waters, 

 since the plaice in the Barents Sea grow much more slowly, and take almost twice 

 as many years to reach a size of 50 cm. or more in length. 



Also the relative frequency of the two sexes shows the primitive character of the plaice 

 stock in the Barents Sea, in a manner similar to that in the case of Iceland. Among 

 the largest plaice of 40 cm. and upwards in the Barents Sea, about 40 "/o are males, 

 as against 60 Vo females, i. e., a considerably higher percentage of males than in the 

 North Sea. The point of intersection of the curves of frequency for male and female 

 is found in the measurement series from the Barents Sea at 44 cm., i. e., at the same 

 length as for Iceland. 



The final results of the investigations as to the changes which have taken place in 

 the stock of plaice in the North Sea, as a result of the intensive trawl fishery are as 

 follows : 



1. It is very probable that the density of the plaice shoals of the North Sea has, 

 with the introduction of intensive trawl fishing, remarkably decreased, the absolute size 

 of the plaice stock being also thereby reduced. 



2. The reduction in the stock of plaice has not affected all size-classes in equal 

 degree, but chiefly the larger and older plaice. This is shown in the catches and 

 landings by a relative decrease in weight and number of the large plaice and increase 

 of the small, as well as in the reduced average size of the plaice. The larger and 

 older males especially have decreased greatly in numbers, and the point of inter- 

 section of the curves of frequency of the sexes has fallen to a lower length. 



If these conclusions be accepted as justifiable — which I think they must be — 

 then we have the answer to the question, whether the productive power of the North 

 Sea is great enough to continually replace the quantity (about 30 to 40 "/o) an- 

 nually taken from the stock by means of fishery. And the answer must, it seems, be 

 a more or less emphatic negative. For if the fishery, as it has hitherto been carried 

 on, has effected such changes in the stock as shown above, it has actually removed 

 more than can be replaced each year. And we can with equal certainty expect, that if the 

 fishery continues, year after year, to take the same quantities of plaice in the future as 

 hitherto, the stock of plaice must become still further reduced, the change being charac- 

 terised by a further decrease in the number of large plaice and relative increase in that 

 of the small, with a corresponding fall in the average weight. 



