— 171 — 
Percentage of fat in herring. 
Centimetres 
| Average = 
& | 16 m | el ol Mar | oe | se | oe 
May TRIO... oc soee 7.62 | 408 | 555| 696 | 804 | 851 | 882 | 7.62 | 7.5 
June A. ali | 497 | 634 | 634 | sıs | 993 114.93 |1433 | ... 
July N BRB | ee lo | coe en Reo TAGS lee) | 
August Ne 1205 | ...| ... | 885) 916 |1148 [11.19 [11.34 | 13.38 |15.94 | 19.22 
September » ....... 36 | ...|'...| ... | 893 | 7.0 | 10.76 | 12.70 |16,38 15.11 | 16.84 
October a bee 12.45 2.1... | 826 11104 | 11.08; |19.88)13.32 | 15.64 
November 12.91 re | ae Moss |15.24 12.74 | 11.59 
Mean... | 1151 | 452) 594 | 7.38 | 9.20 | 9.55 |11.78 | 11.99 | 12.69 14.28 | 15.82 
the amount of fat increases with the length of the fish; thus the fish of 15 cm. exhibited, 
in June 1910, 4.97 % of fat, the 21 cm. fish examined at the same time showing 14.33 %. 
During spring and winter, the percentage of fat is low, in summer and autumn high. 
According to BuzL’s investigations, mature herring may also, at certain seasons of the 
year, exhibit a high percentage of fat. Thus he has found Scottish “fulls” with a percen- 
tage of up to 15 %, whereas the spent winter fish may show as little as 24% %. 
From the analyses made by Buzz, Lra*) draws the significant conclusion that 
the supply of fat increases during the summer and is consumed during the winter, while 
water is excreted in the summer and assimilated in the winter. During the winter, part 
of the dry matter in the system is consumed, and replaced by water, so that no great 
loss in weight is apparent. The quality of the fish, however, is considerably affected. 
Amount of fat in the sprat. 
Buzz has also investigated the amount of fat in the sprat, and drawn up the fol- 
lowing figure expressing the results obtained. The thick black line shows the average 
contents of fat, the dotted line the lowest, and the third line the highest quantity of 
same for the cm. groups. 
This figure distinctly shows the same great seasonal variation which we noticed 
in the case of the herring, the percentage being high in summer and autumn, low in winter 
and spring. Oscar SUND has made a comparison of this variation in the quantity of 
fat with the variations in temperature of the water off the west coast of Norway. The 
results of this comparison are shown in figure 104. 
We notice that the quantity of fat and the temperature of the water both vary 
from summer to winter. In the spring, the increase in fat appears to be almost simul- 
taneous with the rise in temperature; in autumn, however, the two curves by no means 
agree. It is thus impossible to assert that the amount of fat at all times corresponds 
to the temperature of the water; there are evidently other factors to be taken into con- 
sideration. 
The same writer**) has also carefully investigated the age and growth of the sprat. 
*) Publ. de Circ. No. 61. 
**) Oscar SunD: Undersokelser over brislingen i norske farvand. Aarsberetning vedk. Norges 
fiskerier, 3die hefte, 1910. 
22% 
