[Rep. Norw. Fish. Ill 
18 PAUL BJERKAN: THE YOUNG HERRING 
In this report it has been shown that the material collected is 
insufficient to fix the average size of the herring of the different age- 
groups at the time of the cruises, because: 
1) The 0-group was not caught in sufficient number, as a lot of 
the smaller individuals escaped through the meshes of the gear, and 
the catches could thus not be representative of the shoals. 
2) The I-group, which had a suitable size to be taken regularly 
by the implements, has been shown to be distributed in such a manner 
that the smaller individuals live in the shallower water. The catches 
are thus only representative of the shoals at the depths, where they 
are caught, but not of the whole age-group. 
3) The II-group was only caught in small numbers and mostly by 
nets; very possibly a lot of individuals of this group fell off the small- 
meshed nets and could not be taken in those of larger mesh. 
These investigations have shown: 
1) That the 0-group mostly keeps to shallow water, below 20 m., 
which area seems to be the principal nursery-ground of the herring. 
2) That the I-group is mostly found from the 20 m. line out to 
a depth of 50 — 60 m. The individuals of the group seem to be distri¬ 
buted in such a way that the average size of the herrings caught is 
higher, the deeper the water is where they are caught. A continuous 
segregation and a subsequent migration of the larger herrings towards 
deeper water thus seems to take place. The largest individuals of 
the group are found pelagically among individuals of older herrings, 
especially of the II-group. 
3) That the II-group is mostly taken by nets and thus seems to 
live more pelagically than the younger age groups. The individuals of 
the group taken in nets (pelagically) are larger than those taken in 
the trawl (near the bottom). 
As a whole there seems to be a constant segregation and congre¬ 
gation in new shoals according to size and development. This segre¬ 
gation of the faster-growing individuals and their subsequent migration 
to deeper water is most conspicuous in the I-group, but is also marked 
in the II-group. It then follows, that if the investigations are to give 
complete results, catches must be made in all depths from the shore and 
out to the slopes by nets of different meshes and by fine-meshed trawl. 
