Introduction 



1 he investigations we are going to discuss in the following pages have to 

 do merely with one side of fishery statistics. We shall not here deal with the 

 trade-statistics which show the weights and prices of the quantities caught and 

 brought to land by the fishermen of the different countries. Such information 

 can be obtained either from the Bulletin Statistique or similar publications of 

 the International Bureau, or from the authorised statistical works published in 

 the countries concerned. The problems we shall consider are biological and relate 

 mainly to peculiarities characterising the occurrence of certain species in the 

 North Sea; and we shall base our study of them on the vast amount of 

 measurements of different kinds which have been made. The data are exclusively 

 due to work onboard the Fishery-Research steamers and consist essentially of 

 compilations of figures, which may be assigned to the following groups: 



(i). Number of individuals caught. 



(2). L,ength-measurements of individuals. 



Trade-statistics are chiefly concerned with the weights of fish landed, that 

 is to say, with the total marketed weight of each species or its different 

 market-groups; or else they devote themselves to allocating these weights 

 to the different fishing grounds and periods. The material collected by the 

 research-steamers may perhaps help to throw further Hght on some of the 

 questions which a study of such trade-statistics naturally presents, though it 

 cannot be expected to contribute to any extent in elucidating the question of 

 weights. Market conditions and prices have of course nothing whatever to do 

 with the particular side of this subject to which we shall here devote our attention. 



It was our original idea to include in this work all the most important 

 gadoids, as well as the whole area which the International Federation decided to 

 investigate. But it became gradually more and more evident, as we proceeded, 

 that our task would have to be considerably curtailed. In Commission A's 

 introduction to the present report there is shown a delineation of the material 

 which the Commission collected, and it will be seen from this that the returns 

 fit for statistical treatment mainly refer to haddock and cod. No doubt much 

 interesting information has been collected with regard to other gadoids, such as 

 saithe, whiting, ling and torsk: but in their case the returns cannot well be 



