SEA-FISHERIES LABORATORY. 217 



the fiords. The upper parts of it move as a rule outwards 

 with great speed up to 20-30 cm. per second. The lower 

 parts of it move inwards with less speed. The depth 

 of the outgoing current varies. 



The larvae are found in the outgoing as well as in 

 the ingoing current. The fast-flowing surface layers are 

 not so rich in larvae as the deeper inflowing layers; but 

 then they run much faster, and thus transfer just as 

 great masses of larvae as the slow-flowing deeper layers 

 that are more apt to " stow up " the larvae or pack them 

 more closely together. Tides are in this locality of very 

 small account, amounting only to about 10 centimetres. 



Changes may occur in the above-sketched current 

 system. A westerly gale lasting some days will thus 

 blow nearly all the surface water away from these fiords, 

 and bring the salt bottom water, from 20-30 metres 

 depth, right to the surface. After such a gale the salt 

 bottom water will again drop down and pull over it a 

 strong, deep, ingoing water-layer from the Skagerrak. 

 liises and falls in the deep salt-layers of the Skagerrak 

 will produce the same effect. A diagram showing the 

 alterations in the water-layers contemporaneous to the 

 tow-nettings, which I have mentioned above, will clearly 

 illustrate the great changes which took place in the 

 Sondeledfiord as well as also in the neighbouring fiord, 

 the Sandnesfiord. The water-layer, in which the larvae 

 mainly live (the white layer between 20 and 30 per thousand 

 salinity), and where the isopykn of 1,021 is drawn, is 

 subjected to great changes. The salt bottom water rises, 

 sweeps all the water above 20 m. depth out of the fiord, 

 then again drops and sucks in new water of low salinity 

 from the Skagemik. 



Exactly the same changes occur in the Skagerrak, 

 where contemporaneous observations were made two 



