— 170 — 
| 8 
Year Age | Average = = Hes HR — Average percentage 
class = | length incm. ‚large medium small | no | of ister 
| ister, 3 | ister, 2 | ister, 1 | ister, 0 
or | 2) 2 23.1 SDR ARS | 0 0 2.92 
1906 | SR 24.3 | DASEIN RZ 0 0 2.96 
1905 EN 25.5 ee | eal AA ea 0) 0 2.79 
1904 | By 25.9 Er 0 0 2.80 
1903 | 6 | 26.8 | we Bh 1 O 0 2.77 
and spring herring, the proportion of ister is never so high as in the case of the fat herring. 
This will be easily seen from the following table, showing the same factor in the case 
of 380 herring taken on the Viking Bank, west of Bergen, on the 16th September 1909. 
The results here given are stated as above, in percentage of each fat class falling to each 
of the year groups represented. 
| | : 5 
Year Nee | Average | — au si a a: - | Average percentage 
class 8 | length in cm. | ‚large |medium small | no | of ister 
| | ister, 3 | ister, 2 | ister, L | ister, 0 
| | | | 
iGO.) | 28.8 }  @ 33 67 | © | 1.33 
1904 | 5 | 29.1 4 35 56 S| 138 
1903 6x | 29.9 haps} 39 55 3 | 1.42 
1902 Ce | 30.2 | © 42 54 4 1.36 
1901 8 | 30.0 | 0 | 3 47 18 | Lit 
1800 | 9 | 30.5 0 18 68 13 1.04 
1899 10 30.3 0 20 64 16 | 1.04 
Although these fish were taken in September, the most favourable season, the quan- 
tity of ister is far less than in the case of the fat herring. As the herring near their spaw- 
ning, the quantity of ister rapidly decreases, the spent fish all having to be placed in 
Class ©. 
We have thus seen, that the contents of ister varies with the age of the fish, the devel- 
opement of the genital organs in particular being a factor of great significance. In ad- 
dition to this, the quantity of ister also varies greatly according to the time of year; 
this applies not only to the ister itself, but also to the contents of fat on the whole, as 
shown by chemical analysis. 
Amount of fat in herring. 
H. Buzz has at various times made numerous analyses of the amount of fat in her- 
ring. Some of these will be found in the following table*), which shows the percentage 
of fat for each cm. of size from 15 to 24cm, and for these sizes at different times of the 
year from May to November, 1910. 
The table gives an instructive view of the manner in which the amount of fat varies 
both with the age of the fish and the time of year. Within the limits of size here stated, 
*) Aarsberetn. vedk. Norges Fiskerier. 1912. 
