— 178 — 
many years past it has been noticed that the fluctuations in the annual yield appear 
to be not altogether fortuitous, exhibiting rather a very regular wave-like movement, 
with long periods of high and low percentage, each covering several years. Fig. 106 shows 
the course of this movement from 1880—1912. We find here deep hollows for the early 
80’s, the middle 90’s and at the commencement of the present century, with a rise between 
each hollow and the next. The whole appearance of the curve is so regular that it is 
by no means surprising to learn that the question has long been regarded with consider- 
able interest in the fishing industry, the facts as here shown being employed as a basis 
for speculation as to the price in coming years. 
This curve representing the quantity of liver follows very closely that for percentage 
of oil, as will be seen from figure 107. For the statements as to fluctuations in 
the percentage of oil for the years 1880—1912, I am mdebted to Mr. P. M. Heyer- 
18801 2 5 4 856 7 8 91891 254956 7 8 919001 2 54 056 7 8 91901 2 à 
Fig. 107. Curve 1 (scale to right of figure) indicates no. of hectolitres of liver 
pr. 1,000 skrei in the years 1880—1912. 
Curve 2 (scale to left of figure) indicates average percentage of fat in skrei liver 
for the same years. 
DAHL, who has had occasion to personally observe the course of the fishery throughout 
this period, and whose experience in collecting reliable information on the subject, and 
m estimating the representative value of the same, is probably unique. 
It will be seen that the two curves exactly correspond, showing that the fluctua- 
tions in the size (volume and weight) of the liver coincide with those of the percentage 
in volume of the oil. 
It is therefore not surprising that the quality of the fish, its condition in point of 
nourishment, has long been regarded as subject to great fluctuations, exhibiting a 
peculiar periodical movement, with alternating “fat and lean” years, or rather series 
of years. The natural conclusion would then be that these fluctuations were due to 
corresponding variations in the nutritive matter present in the sea, upon which the 
fish depend for food. 
