along the edge of the polar ice. Older age groups keep closer to the polar waters, whereas the 

 course of the drift of young herring passes more easterly, across warm waters of Atlantic origin. 



Herring-tagging during the last few years has shown that the speed of return migration to 

 the spawning grounds fluctuates within the limits of 2.0-6.9 miles a day. 



11. The degree of identity of Atlantic-Scandinavian herring does not remain unchanged 

 during the course of their existence. There can he no doubt that different spawning grounds are 

 isolated from each other. The development of young herring prior to the onset of sexual maturity 

 also proceeds in an isolated manner. Adult herring accomplish the most extensive migrations of 

 all herring from the Atlantic and Pacific oceans. In the opinion of the author, the identity of differ- 

 ent schools that have been hatched on different spawning grounds becomes difficult to determine 

 during that particular period of the herring's life. 



The tagging experiments carried out by the Polar Institute showed that herring feeding far 

 north, around 75° north latitude, as well as those feeding in the west, between Iceland and Jan 

 Mayen, both reproduce off the south-western shores of Norway. 



The study of that particular problem is at the present moment at the initial stages. The 

 identity of herring hatched in different regions may be determined with precision through a sequen- 

 tial step-by-step study of the distribution and migrations of different year classes. 



12. The fecundity of Atlantic-Scandinavian herring is similar to that of other races of large 

 herring (herring from the Maritime, Kamchatka). The low fecundity of all the sea herring is com- 

 pensated by the great number of annual spawnings in the course of their long existence. This is 

 particularly pronounced among Atlantic-Scandinavian herring due to their considerable size incre- 

 ment after the occurrence of sexual maturity as well as their great longevity. 



13. The reproductive capacity of Atlantic-Scandinavian herring is relatively stable, since 

 a great number of different age groups participate in spawning. 



All other races of herring, characterized by a short life-span and a simpler composition 

 of their spawning population, have a lower reproductive capacity. The quantity of eggs deposited 

 by these herring may undergo considerable fluctuations due to the drastic variations in the number 

 of individuals of different year classes . 



14. Atlantic -Scandinavian herring form the largest stock of all herring of the oceans of the 

 world. The catches of these herring have particularly increased in the waters of Norway, where 

 we already observed several overall annual catches exceeding 11-12 million centners. The stock 

 of Atlantic-Scandinavian herring is affected by the fishing of young and adult specimens, which, in 

 opinion of the author, is bound eventually to modify the age structure of the adult stock. 



On condition of a rational organization of fisheries, ensuring maximum preservation of 

 young, the catches of Atlantic -Scandinavian herring may be considerably increased. 



15. Due to the decreasing importance of older age groups in the fishing industry during the 

 last few years, further investigations of the Polar Institute must be directed towards defining more 

 precisely the migrations of young sexually mature herring in order to intensify the exploitation of 

 these herring by the fishing industry . 



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