TABLE 8 . AVERAGE WEIGHTS OF HERRINGS OF DIFFERENT SIZE 

 GROUPS IN 1954 AND 1955 . 



The lowest nutritional condition factor is observed in March-April and the highest in the 

 second half of July and in August, this factor being higher for the herring 27-28 cm. long than that 

 for larger herring. From August to December, despite the gonad development, the nutritional 

 condition factor declines . 



A comparison of the nutritional condition factor with the fatness factor gives grounds for 

 thinking that the decrease in the nutritional condition of the herring during the autumn is mainly due 

 to consumption of the fat deposits . 



The maturity index of the herring for different seasons of the year is subject to sharp vari- 

 ations. During the winter pre-spawning period K3-'reaches its maximum value of 25-29% of the 

 body weight. In March-April, there is an abrupt fall in the gonad weight, which is characteristic 

 of the post-spawning period, when K3 is equal to 1t1 .5% in males and females alike. During the 

 spring-summer months (May, June and July), the period of maximum feeding, the gonad weight 

 does not vary and K3, at 2-2.5%, is almost the same for males as for females, and only from 

 August onwards, when the fish has attained its maximum nutritional condition, do the gonads begin 

 to increase rapidly in weight, although the gonads of the females weigh less during the autumn 

 months (in conformity with their lower degree of maturity), in consequence of which the sexual 

 maturity of the females lags somewhat behind that of the males. By spawning time, however, dur- 

 ing the ovulation period, their K3 indices again catch up. 



In Table 10 and Figures 6E, the maturity factors are given separately for males and fe- 



males. 



The figures for 1955 again show the regular development of the gonads of the herring ob- 



_1/K3 (maturity coefficient according to G. 

 percentage of the body weight. 



V. Nikol'skiy) is the gonad weight expressed as a 



160 



