- i6 — 



The quantity of the plaice landings varies thus very considerably in the different 

 countries bordering on the North Sea, by far the greatest number going to England, 

 which alone brings almost two thirds of the whole plaice production of the North Sea 

 to market. 



The composition of the plaice landings (in size- classes from centimetre to centi- 

 metre: this being the real basis for our calculations, and not the composition according 

 to the ordinary market classes, «large», «medium», «small», which are very variable 

 terms) can only be ascertained through methodical weighings and measurements of 

 market samples. This composition must appear more or less different for the various 

 countries. It depends on: i) the usual legal or generally accepted size-limit adopted by 

 the fishery, below which no plaice, or very few, are brought to land. This size limit is 

 variable: in Germany i8 cm., in England i8 to 20 cm., in Denmark 25.6 cm. 2) the 

 regional extent of the fishery, whether for instance carried on in all parts of the North 

 Sea, as in the case of England, or chiefly in the northern, as Scotland, or southern 

 part as with Holland: from the northern North Sea are naturally landed relatively more 

 large plaice, from the southern parts relatively more small fish. 3) the yearly course 

 of the fishery; whether the plaice fishery of a country is carried on in all months of the 

 year and in all the regions of its fishing territory with equal or varying intensity: the 

 latter is the general rule, and the different countries vary considerably in this respect. 

 Where for instance much fishing is done in summer in the shallower coastal regions, a 

 greater number of small plaice are landed than where the winter fishery in the south 

 and the summer fishing in the deeper northern areas also play a part. 



Market measurements of sufficient accuracy, i. e., taken by scientific methods, have 

 been carried out in most of the countries, but only during the last few years, and even 

 then not always in sufificient extent to ensure accurate calculations. From that 

 country which takes by far the greatest part of all the landings of plaice from the 

 North Sea, i. e. , England, we have fortunately market measurements for three consecu- 

 tive years (1906, 1907, 190S) which have been so extensively and methodically carried 

 out, as to give a very reliable picture of the English landings, both for the whole year 

 and for the single months, and from the various areas of the North Sea. As the 

 English plaice fishery extends over almost all the areas of the North Sea, and is carried 

 on at all seasons of the year, it is reasonable to suppose that the composition of the 

 yearly landings of plaice in England may be regarded as equivalent, without any 

 very serious error, to that of the total landings of all countries. The German market measure- 

 ments for the year 1909, likewise carried out according to an excellent method, confirm 

 this supposition, as also certain Danish and Dutch market measurements. We can thus 

 say that we have a good and reliable knowledge as to the composition of fully 80 °/o of 

 the weight of all the plaice landed yearly from the North Sea. 



Most of the determinations of weight in connection with the market measurements, 

 or failing these, the calculations as to weight arrived at theoretically from the 

 length of the plaice measured, also warrant, as far as the samples in question 

 can be considered as of representative value, the drawing of conclusions, from the 

 weight of plaice landings given in the market statistics, as to the average weight of the 

 individual plaice, and thus as to the total number of fish in the landings. In this 

 manner we can for instance estimate the total landings of plaice from the North Sea in 



