82 
Hjort has stated the opinion and supplied data to support 
it, that the great fluctuations which take place in the quantity 
of liver from year to year are due chiefly to variations in the com- 
position in point of age and size, not in the quality of the fish. 
Now if this be the case, seeing that the greatest quantities of liver 
were obtained in 1890, 1899 and 1908, it is the same as stating 
that large cod tend to occur in nine-year periods. 
The following statistics for catches of cod for Nordland are 
taken from the Report of the Committee appointed by the Fishery 
Board for Scotland to enquire into the Scottish whaling industry, 
page Lo. 
Year. Thousands. Year. Thousands. 
1898 sae 16.897 1907 es 20,906 
1899 oa 17,401 1908 5 16,974 
1900 mals 10,796 1909 tie 19,874 
1901 oa 15,491 1910 a, 17,278 
1902 bale 17,959 1911 we 15,120 
1903 ee 19,441 1912 bes 24,602 
1904 ie 18,598 1913 nar 15.951 
1905 oe 16,831 1914 558 19,306 
1506 on 22 321 1915 aa 25,590 
From the catches of 1903, 1906 and 1907, 1912 and 1915 it 
is clear that if the large fish are predominant in certain years and 
give large yields of liver, governed by a nine-year period, in other 
years small cod come on to the grounds in considerable numbers. 
Great quantities of liver were obtained in 1908, and the next nine- 
year period would give 1917 as the year of greatest liver yield, 
therefore 1903 and 1912 were the years when young cod joined 
the shoals in greatest numbers. Hyjort states that in certain years 
(1903) greater numbers of young fish may be present. These 
years, 1903 and 1912, were years of great activity of Atlantic 
waters, and according to the above data they are marked by large 
numbers of young cod amongst Norwegian shoals of adult cod. 
The activity of Atlantic water in 1920 was followed by what is 
considered a high number of young herrings in our spring spawning 
shoals, and the activities of the year 1921 coincided with the poor 
condition of North Sea herrings. It is possible that the chief 
-sause of the fluctuations in the yield of liver from Norwegian cod 
is to be found in periodic changes in the flow of Atlantic waters, 
which tend to drive young fish into the shoals and lower the 
conditions of the older fish. 
