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Fluctuations in the currents. 
In view of this, attention was drawn, at a very early date, to the question of changes 
in the sea itself, and the study of the subject was soon included in the programme of 
the Norwegian fishery investigations. 
In the 90’s, H. H. Gran and the present writer*) arrived at the conclusion that 
the first necessity in any investigation of the changes in the sea must be a study of the 
so-ealled Atlantic current, or Gulf Stream, which passes from the Atlantic through the 
Faroe-Shetland channel into the Northern Ocean. Despite the paucity of means at 
our disposal, we succeeded in carrying out a summer and a winter section of this current. 
Our observations of salinity did not, unfortunately, attain such a degree of accuracy 
as has been rendered possible of late years by the developement of this branch of marine 
research in the course of the International Investigations. From the observations as 
to temperature, however, and distribution of the pelagic organisms, we could not but 
conclude that the fluctuations in this current were of so great extent as to render them 
of the highest significance to the animal life in the Northern Ocean. 
When the Norwegian research steamer “Michael Sars” was built in 1900, I there- 
fore instituted, as part of the annual programme of work for the vessel, cross sections 
of the Atlantic Current, to be carried out at the same time of year (in May), with a view 
to comparing the volume of the current from year to year. The route was laid from 
Sognefjord to a point east of Iceland (the Sognefjord section) and thence to Lofoten 
(the Lofoten Section), making two sections of the current at different latitudes. These 
cruises were carried out in the years 1901—1904, care being taken to hold the same course, 
as nearly as possible, each year. 
Helland-Hansen’s and Nansen’s comparison of fluctuations in the ocean 
currents with those of the fishery. 
The material thus collected was dealt with by B. HetLAnD-HanseEN and F. NANSEN**), 
who endeavoured, in the course of the work, not only to make clear the fluctuations 
in the volume of the currents, but also to discover how far any definite relation could 
be said to exist between these and the fluctuations of the fishery. 
Figs. 108—11 show the sections drawn by HELLAnD-HAnsenand Nansen of the Atlantic 
current along the southern route, (the Sognefjord section). The shaded surfaces show 
the cross section of the so-called Atlantic water, (salinity over 35 % ) the darker shading 
indicating water of over 35.2 % salinity. For these, i. e. for all water over 35 % sali- 
nity, the average temperatures have been calculated, both in the Sognefjord and the 
Lofoten section. The figures obtained were taken as characteristic of the temperature 
of the Atlantic current during the years in question, and curves were accordingly drawn 
for purposes of comparison with certain features of importance in the fishery. We may 
here consider some of the comparisons made. 
*) Currents and pelagic life in the Northern Ocean (in Report on Norwegian marine investiga- 
tions 1895—97). Bergens Museums Skrifter, Vol. 1, 1899. 
**) Die jährlichen Schwankungen der Wassermassen im Norwegischen Nordmeer etc. Inter- 
nationale Revue der ges. Hydrobiologie und Hydrographie: Bd. II, Hefte 3. 
The Norwegian Sea. Report on Norwegian Fishery and Marine Investigations. Vol. IT, 
No. 2, 1909. 
23* 
