APPENDIX G _ 12 ^ 



The most important pelagic fishes within the region of the international investigations are 

 the herring, the garfish and the mackerel. We must add to this, that almost all the economi- 

 cally important species are pelagic, especially in their earliest stages. 



Of the international investigations accomplished up to the present, some have importance 

 also for the comprehension of the geographical distribution of these fishes. 



Herring have been taken hy driftnets in the most different parts of the North Sea, and 

 it was thereby made apparent, that their sexual organs were differently developed according 

 to the distribution of the different streams; for example, the "Michael Sars" in September 

 of this year, caught the "fat-herring" in the eastern Baltic stream of the North Sea and ripe spaw- 

 ning or spawned herring in the Atlantic stream to the west, or the western coastal stream. 

 These important observations should be thoroughly studied further on the working hypothesis, 

 that the "fat-herring" of the eastern North Sea belongs to a branch or race spawning 

 in spring on the Norwegian coast and is distinct from the summer or autumn herring spawning 

 on the western and southern North Sea banks, and that the boundary between the oceanic 

 currents is also the boundary of these two races. 



The international research-steamers have also been specially engaged in the study of the 

 pelagic young stages, as the catches of the fishing steamers can give no information inithis 

 direction. 



In sections II and m, more detailed evidence wül be given of the great influence, the 

 oceanic currents have on the distribution of these pelagic young fishes. 



During the observational cruises in the Norwegian Sea, observations were also made on the 

 pelagic wanderings of the fishes, which were formerly believed to lived only on the coastal 

 banks or on the slopes of the Norwegian Sea towards deep water. 



Thus, the following fishes have been observed in the uppermost layers, to 180 m. deep, 

 out in the Norwegian Sea far from the coasts and over depths of 1800 — 3600 m; herring, cod, 

 haddock, green cod and Norway haddock (Sebastes viviparus); west from Iceland also, the 

 large shark (Somniosus microcephalus), likewise herring and Norway haddock in considerable 

 quantities, the latter for example to the number of 65 on 600 hooks over 2900 m depth. 

 The young just hatched were also taken in large quantities over great depths, both near 

 Norway and near Iceland. 



Having endeavoured in the foregoing to give a survey of the geographical distribution of 

 the different fishes, we will proceed in the following pages to an account of the fisheries 

 investigations themselves. 



The earliest fisheries investigations during the sixties of last century showed already, that 

 all practical fishery questions, with which wide circles were then engaged, could only be under- 

 stood and solved by thorough acquaintance with the natural history of each separate species. 

 FoT this, the investigation of the development, rate of growth and migrations of the different 

 species, are of special importance. 



In the following pages, we give first of all a short survey of the general methods of work, 

 and of the aims and results of the international fisheries investigations (Section II), and then 

 as a special example, the results in more detail of the investigations into the natural 

 history of the cod (Section III). 



