raie 
Fig. 36 shows the composition in point of size. In the sample from the east coast 
of England (7) two groups are slightly indicated, one about 23 and one about 26 em. 
This presumably corresponds to the mixed composition of the sample, consisting of fat 
herring and spring spawners, (coast herring). The Dogger Bank sample (4) shows a 
distinct maximum at 27 em., that of the Viking Bank fish (2) at 31 cm. 
In like manner, Fig. 37 indicates a maximum for the English coast sample (7) of 
the year class 1908, that from the Dogger Bank (4) of 1906, and that from the Viking 
Bank (2) of 1904. That this difference in composition with regard to age does not alone 
determine the difference in size will be seen from the dotted curves in Fig. 36. These 
curves show the variations in size for the year class 1904 among the Dogger Bank and 
Viking Bank fish: it will be seen that the individuals from 1904 were far larger among 
the Norwegian coast herring than among the Dogger Bank fish, (which is also evident 
from the average sizes for the year class as shown in the table). The Dogger Bank fish 
therefore consisted, in 1911, of smaller individuals, both absolutely and in relation to age. 
Numerical relation of the year classes in different parts of the North Sea. 
From this it would seem that we may hope, even with the present material and 
with simpler methods, to obtain a view of the composition in point of age of the spawning 
or grown shoals of herring in the North Sea. In the charts Fig. 38—40 therefore, a 
number of the results from the age determinations of the 1911 samples have 
been given. The charts have been drawn up with a view to separately representing 
the numerical value of the year classes in all the samples examined. All stations have 
therefore been marked on a chart of the North Sea, a circle being drawn at each with 
radius according to the percentage of the year class as represented in the sample taken 
there. Thus the chart in Fig. 38 gives a graphical illustration of the percentage of the 
1904 year class in the North Sea samples from 1911. Fig. 39 shows the same for 1906, 
and Fig. 40 for 1908. These three year classes, 1904, 1906 and 1908 were, it will be re- 
membered, the most prominent in the three different types of composition with regard 
to age given above. 
In the chart for 1904 year class, Fig. 38, we find large circles along the 200 metre 
line in the northern and north-eastern part of the North Sea; in on the banks, however, 
the values are everywhere small, decreasing southwards, except for August—September, 
when we find somewhat larger circles (10—20 %) on the Dogger Bank. 
The chart for 1906 on the other hand, shows very small circles along the 200 metre 
line, and larger, (20—40 %) from the Shetlands southward along the east coast of Scot- 
land and England and on the Jutland Bank. As we shall see later on, similar conditions 
prevailed on the coast of Bohuslän. In the immediate vicinity of the coasts, however, 
somewhat smaller circles will be noticed, as for instance off the coasts of Scotland and 
England. 
The chart for 1908 shows only very small values in the north-eastern part of the 
North Sea, all, with one exception, being less than 10 %. Nearer the Shetlands they 
are somewhat larger, while in the southern part of the North Sea they amount to over 50 %. 
A comparison of the three charts seems to indicate: 
1) That in the study of age composition also, it is possible to follow the migration 
of the Norwegian herring out to the edge of the banks in the North Sea, and here to 
