SEASONAL CHANGES IN PLANKTON AND 



1/ 

 FEEDING MIGRATIONS OF HERRING" 



E. A. Pavshtlks 



INTRODUCTION 



In recent years, the Soviet herring- fishing industry has covered almost the entire feeding 

 area of the Atlantic -Scandinavian herring. 



The biology of the herring depends on the seasonal changes in the marine plankton. At the 

 same time, the schools of feeding fish affect the composition and quantity of plankton. Seasonal 

 phenomena in the plankton, on the other hand, depiend, to a considerable extent, on solar radiation 

 and the hydrological conditions of the basin. 



Regular observations of the dynamics of plankton production, first in the Barents Sea, and 

 during recent years in the Norwegian and Greenland Seas, have made it possible to establish ap- 

 proximate periods for the plankton production and the duration of the biological seasons for the var- 

 ious regions of these seas . 



A study of the principles governing the development of marine biological seasons, as well as 

 a disclosure of the reasons for the migration of herring are necessary for the proper organization 

 of a survey of the fishing industry (20). 



In this work, the results of the research into the influence of annual fluctuations in the peri- 

 ods of the plankton production for the fattening of herring in the Norwegian and Greenland Seas 

 have been summarized. 



This research was conducted by the Polar Institute from 1948 to 1955. 



History of Research 



The following Soviet scientists were engaged in a study of the seasonal phenomena in the 

 northern seas plankton: P. P. Shirshov (30), V. G. Bogorov (2, 3, 4), B. P. Manteyfel'(17, 19), V. A. 

 Yashnov (31). These investigations were connected with the utilization of the northern sea route 

 and the development of the fishing industry in the North. 



In the Arctic or polar seas --this was established by the studies conducted by V. G. Bogorov 

 and B. P. Manteyfel'- -several plankton complexes which are characteristic of the various biological 

 seasons, can exist simultaneously in close proximity (at times even in one and the same region). 

 V. G. Bogorov furnished a description of the biological seasons in the plankton of various seas. He 

 also compiled a chart of the changes in their duration. 



PINRO investigations in the Barents, Norwegian and Greenland Seas confirm to a consider- 

 able extent the accuracy of the principles --disclosed by Bogorov- -that govern the seasonal plankton 



1/ Fisheries Research Board of Canada Translation Series No. 175. 



104 



