We believe, however, that in the given case such an explanation is not sufficiently sub- 

 stantiated. In the case of overpopulation of a water basin by fish, the deterioration in living 

 conditions also affects the immediately preceding and the following year classes existing at the 

 same time in the given basin. In the Barents Sea, we observe an altogether different phenomenon. 

 The several successive generations simultaneously populating the basin differ considerably from 

 each other in the growth rate. Thus, the abundant 1930 year class was characterized by a low rate 

 of growth, whereas the subsequent generation, i.e. the herring hatched In 1931, was not numerous 

 and developed at a hlgji rate . We believe that if the intraspecies relations were indeed the deter- 

 mining factor, the 1931 year class should also have been characterized by poor growth, since it 

 too developed in conditions of "overpopulation" of the sea by fishes of the 1930 year class . We may 

 quote a few more examples of the simultaneous existence in the Barents Sea of year classes 1936 

 and 1937, generations hatched in 1947 and 1948, etc. 



We are Inclined to attribute the differences in the growth rate of different year classes to 

 the environment of the first few years of the life of fish, the "selection" of which is determined by 

 the drift of fry. Such an explanation is apparently closer to the truth, since there exist irrefutable 

 facts showing that the fry of abundant year classes spread mainly in the eastern and northern dir- 

 ections, whereas young herring belonging to poor year classes spreads mainly westwards. 



The importance of abundant herring year classes for the coast and littoral fishing industry 

 increases in view of these fishes' long stay near the shores. Fat herring play a particularly im- 

 portant role in commercial fishing during the years when they remain in the littoral zone and enter 

 the fjords. The factors accounting for the mass movement of fat herring into fjords have not been 

 sufficiently studied as yet . 



Intensive movements of herring into the gulfs of the Murman shore in the fall of 1933 and 

 1934 have been explained differently by different authors. Manteyfel' and Boldovskiy (13) believed 

 that these movements are a regular phenomenon, inbred over many years as a result of the search 

 for optimum conditions of existence during the winter (low temperatures contributing to the drop 

 in metabolism). 



Glebov (9) shared the above viewpoint to a certain degree. However, he observed correctly 

 that neither the summer, nor the winter movements of herring into the gulfs are an inevitable phase 

 in the life cycle of these fish. Finally, Mlronov (17) endeavored to prove the connection existing 

 between the herring movements and changes in the earth's magnetism in the region of Barents Sea. 

 These latter hypotheses were erroneous in view of the fact that the authors attempted to find an 

 explanation for the movements of herring in conditions of external environment only, either ignoring 

 (17) the organism proper, its distribution, abundance, and physiological condition or considering 

 it of secondary importance (9). 



The general level of modem knowledge of herring biology enables us to discuss factors 

 responsible for these movements . Mass movements of fat herring into the gulfs are always pre- 

 ceded a year or two years by summer movements of sinall herring. The study of age composition 

 of the herring catches obtained over a period of several years in the coast zone of our country, 

 along the coast of Murman and Norway, convinced us that the year classes making such movements 

 en masse are very abundant. Thus, the high catches of fat herring obtained in Norway in 1909 were 

 due to the exceptionally abundant year class of 1904, which determined the success of the Norwegian 

 fishing industry for over 15 years . 



Movements of fat herring observed in 1928 were due to the abundant year class of 1925, 

 those observed in the Murman region, as well as in Norway, in 1933 and 1934 - to the 1930 year 

 class, which was extremely abundant for both the Murman and Norwegian schools. 



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