300 

 V3 

 UO 4 

 223 



ZOO 



iT f?s 

 o 



00 



tio 



a t25 

 09 



3 



2 wo 



?i 



iO 



Zi 



Arc- 



• Summer -3 pawning 

 o Spring- spawning 



Summer 66.s — 

 Spring ^^^ ^o.i 



1~\ 7~ 



1^0.1 \ in. 5 



6i,,5\ 66.0 



til^ 



70.S 



10 



i87,7 189,9 



75,9 \ 74.5 



11 



BO 0,7 



78.8 



12 



13 



1S5.5 



76.it 



233,0 



Ai 



« 



15 16 



200,5 \'3?, 6 — 



78, d\ 7e.6\ 76,0 



Figure 10. Fertility of summer and spring herrings . Dependence of fertility on age. 



Weight and Fatness 



The weight of the herring depends on its size, fatness and the stage of gonad maturity. 

 After spawning, the herring feeds intensively. Average weight and fatness increase with the amount 

 consumed. 



According to our observations, the Indexes of weight by years do not show any sharp diver- 

 gences, and this allows one to combine the material on weight over a period of three years. 



Table 14 gives average weight of adult herring of the summer race by times of capture. 

 For comparison with changes in weight in the summer herring, we give data for the spring race. 



The weight of the summer herring increases during June and July. In August, the average 

 weight decreases and this is related to^he approach of the period of large-scale spawning. The 

 weight of the spring herring increases steadily during the whole summer period. The small diver- 

 gence from this rule in the case of young specimens is to be explained by the paucity of the material . 



Table 15 gives the coefficients of fatness before and after spawning. In all cases, the co- 

 efficient is considerably higher in the pre-spawning period than in thp post-spawning period, which 

 is to be explained by the sharp change in weight consequent upon the loss of the sexual products. 



The fattening of the summer herring takes place apparently in two periods: before spawn- 

 ing, in April to June, and after spawning in August-September. 



188 



