At that time, we expressed the thieory that extensive migrations to the north are only made 

 bfy herring over 8-9 years of age and over 29-30 cm. in length; the young fish, having a higji rate 

 of growth and measuring at the age of five years 28-29 cm. in length, migrate with the older fish. 

 The main bulk of the six- and seven-year-old herring does not participate in these particular migra- 

 tions, remaining isolated from both the younger herring that populate the Barents Sea, and older 

 herring migrating considerable distances northwards . We voiced the supposition that herring be- 

 longing to these age groups might be found during the summer on the border of the Barents and 

 Norwegian seas, in the region of the western channel, between the North Cape and Spitsbergen 

 branches of the Norwegian current and in the southern zone of the Spitsbergen branch, south from 

 73° north latitude. 



While studying the biological composition of herring caught in the Spitsbergen current in 

 1946 and 1947, we found identical regularities: there were very few fish 26-28 cm. in length in the 

 catches, the specimens over 8 years of age prevailed, whereas single specimens of relatively young 

 herring that had already spawned were characterized by a high growth rate. 



These observations convinced us that the aforementioned hypothesis concerning the less 

 extensive migrations of herring at the age of 6-8 years was correct. In order to solve ultimately 

 this problem, in 1948, L. A. Bakunenko and M. M. Vykhrystiuk set up under our supervision a re- 

 search on the biological composition of the herring schools caught in the Spitsbergen current. They 

 analyzed the age composition of the catches, studied the growth rate of different year classes using 

 back calculations of lengths at each year of life, and examined the spawning marks to establish the 

 age at which these fish became sexually mature. Simultaneously, they analyzed the herring data 

 from the southern zone of the Barents Sea . 



The main results of the investigations thus carried out may be outlined as follows: herring 

 up to 25 cm. in length are found in the Barents Sea, whereas specimens 29-32 cm. in length popu- 

 late mainly the region of the Spitsbergen current . 



The main bulk of catches obtained in the southern zone of the Barents Sea consists of young, 

 sexually immature fishes at the age of 4-5 years; 6-7-year-old herring were rarely found; in the 

 Bear-Spitsbergen zone the majority of catches consisted of specimens over 8-9 years of age (Fig. 3). 

 The differences in the respective growth rates of young and older specimens proved to be consider- 

 able. Thus, using back calculations of lengths at each year of life, it was found that the length of 

 6-8-year-old herring that were caught in the Spitsbergen current was in the fourth year of life 22.3 

 cm., In the fifth year 26.1 cm., and in the sixth year 28.1 cm. 



Herring of older age groups reach such lengths 1 or 2 years later. L. A. Bakunenko and 

 M. M. Vykhrystiuk, having examined the spawning marks, established that younger specimens have 

 a relatively greater number of such marks as compared with the older fish. Thus, the 5-6-year- 

 old specimens found in Spitsbergen current had one to three marks, averaging 1.5 to 1.8. Sexual 

 maturity occurred in these fish at the age of 4-5 years, in certain specimens even at the age of 3 

 years . In fish 10-12 years of age we observed 5-6 spawning marks, i .e . they became sexually 

 mature at the age of 5 years and later (Table 4) . 



Thus, the investigations by L. A. Bakunenko and M. M. Vykhrystiuk showed that only her- 

 ring of the older age groups migrate far into the north, via the Spitsbergen current. The main bulk 

 of 6-7-year-old herring, having a medium or low growth rate and which have already spawned once 

 or twice, remains outside the Barents Sea, but, undertake no feeding migrations into northern lati- 

 tudes. 



31 



