salinity of the water, and the influence of light. By observing and stating the facts, we will try to 

 find the possible laws in the development of the gonads in the various stages. 



In the Barents Sea, the hydrographical conditions are very complicated. The Atlantic cur- 

 rent has a great influence, but the amount of warm water introduced with this current in the Bar- 

 ents Sea is not the same in different years. We will therefore compare the findings of herring in 

 certain stages with the temperature and salinity of the water during the same periods. 



The physical -chemical factors undoubtedly influence the processes of life in fish, but it is 

 difficult to state how important they are . Some scientists infer that the temperature is influencing 

 nearly all the life processes of the fish (migrations, feeding intensity, time of spawning, and so on). 



Glebov (13) infers that the migration of the herring to the coast is mainly governed by the 

 hydrographical factors, and that any periodicity in these factors will be reflected in the migrations 

 of the herring (will cause a similar periodicity). 



Ambroz (4) is of the opinion that the spawning migration of the Pacific herring into the Bay 

 of Peter the Great is determined by the temperature conditions in the bay. He divides the herring 

 from this locality into three groups: herring older than three years are cold-loving; three-year- 

 old herring love the mean temperatures, and herring one-and two-years-old are heat-loving. 



The results of Ambroz were obtained by comparing the catch statistics with the temperature 

 of the water, and may therefore be regarded with a great deal of scepticism. We do not agree with 

 his argument that the spawning migration of the herring is determined by the temjjerature only, 

 without considering the physiological state of the fish, especially the stage of maturity. 



If the Pacific herring get more and more cold-loving with increasing age, then the Murmansk 

 herring, according to the "temperature theory", become more and more heat-loving. The temper- 

 ature theory merely states facts without any explanation. It may be said that the 0-group of the 

 Pacific herring is heat-loving, but the 0-group of the Murmansk herring is cold-loving. 



The real conditions can only be understood by studying the total life cycle of an organism 

 with allowance for all factors . 



With this point of view, the process takes place in the following way: a great number of the 

 fry of the Murmansk herring are carried to the eastern areas of the Barents Sea by the North Cape 

 branch of the Atlantic current . The fry are also drifting into the White Sea . The eastern parts of 

 the Barents Sea, being very shallow, are warmed during the summer. A great development of 

 plankton takes place in these areas. The distribution of the fry is not limited to the narrow branch 

 of the Atlantic current. As the warm water of the Atlantic current is likely to be very poor in food, 

 the fry is forced to migrate beyond the borders of the current (towards the east, into the White Sea, 

 and into the fjords). 



During the growing period, the herring accumulate a large reserve of feit. The sexual in- 

 stinct still does not induce the herring to migrate westwards. In winter, when the temperature 

 sinks very rapidly in the coast areas and in the eastern parts of the Barents Sea, the herring move 

 to near the bottom, where the temperature is somewhat higjier than at the surface. This migration 

 to the water layers near the bottom in winter is a very economical utilization of the energy of the 

 organism. Having wintered under comparatively severe conditions in the eastern area, the young 

 herring will find an abundance of food in spring, without migrations to any great extent. 



With increasing age, the herring's distribution is more and more connected with the branch- 



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