EEE OR) ao 
%, 1904 in 1907 1908 1909 1910 1911 1912 1915 
Among fat herring .... 51.3 37.8 16.9 4.5 0 0 0 
» langes Rare 7.70 51.6 48.8 59.6 46.0 52.5 58.6 
» SON? yg s00 1.6 34.8 43.7 77.5 70.0 64.3 64.7 
The year class 1904 was, as here shown, extremely numerous in most of the samples 
of fat herring, (over 40 %) up to 1909 inclusive. In 1910, the year class is only poorly 
represented, and then disappears entirely from the shoals of the fat herring. At the 
same time, we find that from 1907—1910, the year class 1904 is continually increasing 
among the large and spring herring. In 1910 and 1911 it reaches, among the latter, 
the very high percentage of 77.3 and 70.0, and even in 1912 and 1913 it is over 64 %. 
It may now be of interest to consider, first of all, the composition in point of size 
of the spring herring in the years when the year class 1904 had disappeared from among 
the fat herrmg, and had become so numerous in the spring shoals. For this purpose 
four samples from the northern spring herring district, taken in 1910—1913, have been 
selected. 
Il II 
| . Percentage for sizes in cm. ee ae a se 
| ee = ble £ TRES 
I B | Ie ~ || à of year class 
| 26 | 27 | & | 29 | 30 | si | æ | 33 | 54 | 36 | 37 in cm. 1904 
pl cm = 
AMD) ooo oe 5.4 lise 26.1 | 32.5 | 149 27 | 27 | 1.4 | ; | re AR 2 28.6 28.4 
IS, Lao ae | 13 | 68 |28.2 135.2 114.7 | 7.9 | 3.1 | 08 | 08 | 03 30.0 29.7 
TD no | 1:0 | 2.2 |33:5 [eee 27.8 |114 |) 52 12| 03 | 0:3 30.5 | 30.3 
DE 6 soe ee | 34| 95 502 [984 | 87) 12) .. | .. Sin ests 
Fig. 15 gives a graphical representation of the figures here shown. The full line 
curves show the percentages in point of size for the whole samples, the dotted curves 
those of the year class 1904. It will be immediately seen that a distinct increase in the 
size of the spring herring took place in 1910—1913, while at the same time an increase 
in the size of the mdividuals belonging to year class 1904 is also apparent. In the four 
samples, the year class 1904 furnished the following percentages of each: PAC { 
1OLO 400% 78.0 We 
ICRA 71.2 f 
ICH RE 61.6 { 
AIO NE 70.2. 
With these high percentages in view, it would seem very natural to consider the 
excellent agreement of the increase in size of the whole sample of spring herring with 
the increase in size of the year class 1904 as due to the fact that this year class has been 
a determining factor in the size of the whole sample. 
A full and complete view of the position of the year class in the samples can, however, 
only be obtained by considering together the average percentages for all year classes 
in the samples examined. This will be found in the following table, which shows the 
A 
