12 
PAUL BJERKAN: THE YOUNG HERRING 
[Rep. Norw. Fish. Ill 
Of the summer samples, that from the Firth of Forth is too small 
to give an approximate value for the average length of the age group, 
only 4 individuals, and by the other samples we must bear in mind 
that the trawl with certainty only fished herrings of down to a length 
of about 10 cm. The average length, as found above, is thus most 
likely too high. From the actual lengths, as recorded for the samples 
from Nissum Fiord and Heligoland Bay, we see that no individual 
smaller than 8 cm. has been taken and, judging from the presence of 
smaller individuals in the Firth of Forth sample, it is most likely that 
they have been present in the other samples too, but have escaped 
through the meshes of the trawl together with some percentage of the 
nearest length-groups (8 and 9 cm.) 
Fig. 4 shows the length-frequency curves of the 0-group of the 
three samples from Heligoland—Nissum (Samples 8, 9 and 10). The 
dotted lines represent each of the samples, while the continuously-drawn 
broken line shows the average-frequency curve of the three samples. 
In the smooth continuously-drawn line an attempt is made to show ap¬ 
proximately how the frequency might fall if the trawl had taken all lengths 
of the age group alike. As seen, the average length is then supposed 
to fall close upon 9 cm. All these summer samples have been taken 
medio June. 
The stations of the autumn cruises lie farther out at sea and this 
is most likely the reason why only one individual of the 0-group was 
taken during the cruises. 
