— 13 — 



over the regions investigated, as is shown in the accompanying Chart (Plate I). The 

 red points on it indicate the stations which were visited on the seasonal cruise 

 during Aiignst 1903. 



The aim of this method is to determine the changes occurring during the course 

 of the year in the hydrographical conditions and in the distribution of the plankton, 

 and also to some extent in the distribution of the (so-called pelagic) fish-eggs, 

 larvœ and young fish floating in the sea. List III gives a review over the seasonal 

 cruises carried out by the various countries. 



The seasonal cruises are naturally not suited to the study of the problems 

 connected with the influence of the deep-sea fishery on the stock of fish and the 

 migrations of the fishes, nor those concerned with the biological investigation of 

 the sea in general. In these cases, the scientific investigations must employ the 

 methods of the practical fisheries and study their results, partly by control-experiments 

 on the fishing-grounds and investigations in the laboratories, partly by critical treatment 

 of the statistical data collected in the various countries. Of great importance in 

 this connection, are the measuring and setting out of marked fish, especially flat-fish, 

 in the North Sea, the Skager Rak, Kattegat and Baltic. This method is used 

 systematically on a large scale in the international investigations. 



List III: Seasonal Cruises 



The practical fisheries experiments and investigations are carried on during 

 every season of the year, in cruises which last several days or weeks, even some 

 months, by the specially built or chartered steamers. List IV, p. 14, 15 and 16, 



