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to the number of units ; or, in other words, the single catches which compose a con- 

 stant total catch will be smaller and more numerous the greater the number of the 

 fishing vessels and their fishing days (units of capture). For instance, the average 

 catch per cutter day of the cutters from Esbjerg fishing in the North Sea has decreased 

 from 564 kg. in 1897 to 254 kg. in 1908; fishing was however only carried on in 1897 

 for 2313 cutter days, as against 8418 in 1908. During the first of the mentioned years 

 these cutters took 1,305,660 kg. of plaice from the stock of the North Sea, in the last- 

 named year 2,130,172 kg. Given a constant stock and constant and equal encroachment 

 upon the stock, then the yield per cutter day would have decreased from 564 kg. in 

 1897 to 15s kg. in 1908. The stock has thus, with the increased intensity of the 

 fishing, been more severely (about 1.6 times) encroached upon. Such an absolutely 

 more intensive fishing of the stock can possibly, if continued for some considerable time, 

 lead to an absolute decrease in same. This would be shown by the fact that the 

 increase of the yield which took place with the increased absolute intensity of the 

 fishing, became less in course of time, and finally only slightly noticeable, if at all, in 

 spite of the utmost exertions on the part of the fishery. This is as much as to say, that 

 the yield of the fishery is now no longer, as was formerly the case, merely the interest 

 on the capital represented by the stock of plaice, but already contains a portion of the 

 capital itself 



Various signs seem to suggest that our fisheries in the North Sea, as far as they 

 are carried out by means of the trawl, and in particular the plaice fishery, have already 

 reached the point just referred to, and that an actual reduction of the stock of plaice 

 has thus already commenced. 



It is very probable then, that the shoals of plaice in the North Sea are not so 

 dense as heretofore; the larger and older plaice are much more rare, and thus also the 

 average in age, weight, and size have been reduced. And it is equally probable that 

 all this is a result of the intensive trawl fishery, dating from the commencement of 

 same. 



3. Though it is unfortunately impossible to learn anything about the composition 

 of the landings of plaice from the North Sea at a time when the fishing of this sea was 

 not yet so intensive as now, we can yet do so with regard to certain sea districts 

 outside the North Sea, which have only of late years been fished at all, and which, in 

 comparison with the North Sea, can still be regarded as virgin fishing grounds. We 

 may therefore also consider the plaice stock on such grounds as being more in its 

 original condition than is the case with the North Sea. A comparison of the composi- 

 tion of such stocks, which have only of late been fished, with one which has for a 

 long time been subjected to intensive fishery, may perhaps throw some light upon 

 certain alterations in the stock which may be regarded as due to increased fishing. 



First in this respect come the fishing grounds of Iceland. A comparison of these 

 grounds with the North Sea is the more valuable for our purposes, since the Iceland 

 plaice, while a distinct race, yet resemble in racial characteristics the plaice of the 

 North Sea, especially the so-called northern plaice; moreover, and this is especially 

 valuable, the investigations as to the age of the Iceland plaice have shown that they 

 do not differ essentially in this respect from those of the North Sea; Icelandic and North 



