During the Soviet researches in the Norwegian and Greenland Seas with the object of dis- 

 covering the base of the raw materials of the Soviet fishing industry, material on the summer- 

 spawning herring was collected in the region of Iceland. 



In 1948 and 1949, Soviet vessels fished for herring in the regions customarily exploited by 

 the Icelandic boats. Later the catching regions were considerably extended, and the season too 

 was extended into June and September. This gave us the opportunity of collecting considerable 

 material on the summer -spawning race and of tracing the distribution of pre-spawning and post- 

 spawning schools. However, our investigations were not able to supplement the data on the con- 

 ditions of reproduction since the spawning of the summer race occurs in Icelandic territorial waters 

 or near them. 



In various regions, summer-spawning herrings comprised up to 20-25% of the catches of 

 our fishing industry. 



We have investigated the age composition and the growth rate of the Icelandic herring and 

 studied the structure of the scales, in particular the first ring, which, according to our observa- 

 tions, is formed during the first winter - which is denied by previous investigators. This enabled 

 us to single out summer herrings not only according to the stage of growth but also according to 

 the scale structure. 



In the Iceland region, during the period of our investigations, more than 65,000 specimens 

 of herring were measured and of these 8 , 000 were subjected to a complete biological analysis . 



The age of the herrings was determined under a microprojector (7 x 11). The growth rate 

 was calculated by the method proposed by V. R. Aleev /Suvorov (1)/. 



Fertility was determined by the usual method. To verify the fertility, a sample of roe 

 equal to 1 gm. was taken from various parts of the ovary. The quantity /number of the eggs in the 

 sample was multiplied by the total weight of the gonads. The total quantity of the roe was approx- 

 imated to 0.1 thousand. In addition to the number of eggs, the dimensions of the eggs were deter- 

 mined too, by measuring the diameters of 10 eggs . 



Making use of our observations on the conditions of distribution of adult herring and the in- 

 vestigations of Icelandic scientists into the diffusion of the larvae of the summer herring, we en- 

 deavored to reproduce the peculiarities of the life cycle of the summer -spjawning race, which, as 

 the experience of our fishing industry has shown, may be of fundamental significance for the Soviet 

 herring fishery. 



Region, Periods and Conditions of Reproduction 



The regions and periods of reproduction of the summer-spawning herring can be established 

 from the stages of maturity of the gonads and the early stages of the larvae . 



In the first half of the season Qune), off the north-west coast of Iceland, herring having a 

 gonad maturity stage Vn-II and n to III dominated in the catches. These herring must be included 

 in the spring race. Simultaneously with these, fish having gonad maturity of stages IV and V were 

 found. These specimens must be included among herring of the summer race. Herring with run- 

 ning/flowing gonads (VI stage) were observed in the nortliern regions every year during July and 

 August, but only in single numbers. From the second half of August, the presence of individuale 

 which had spawned- -of the VII and VII-II stages, and also the 111, IIl-IV and IV stages --was estab- 

 lished. The former must undoubtedly be included in the summer -spawning race; the latter, in the 



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