— 21 



KNUT DAHL 



Wo will instantly observe that eggs as well as larvae are I'uund in y;real number 

 considerably above the level where the normal maximal specific gravity of eggs and 

 larvae (1-021) is to be Ibimd in the water column. This variation I am inclined to 

 attribute to the current. The current system of this fjord is far more active and vigo- 

 rous than that of the Sondcled-Fjord and eggs and larvae are evidently raised by the 

 current from levels where they would keep in more still water. 



Parallel examples might also be quoted from the S0ndeled-Fjord where the distribution 

 of eggs and larvae shows a tendency towards a similar variation when stations with 

 weak and strong current are compared. 



The other kind of variation in the vertical distribution of eggs and fry is illustrated 

 by the following comparison between the number of cod eggs and fry obtained in 

 the diferrent levels on two occasions. 



Sendeled-Fjord st. I— IV 



We observe that eggs as well as fry have decreased in the deeper layers, and 

 increased towards the surface parallel to the alterations in specific gravity, which have 

 taken place. The alterations in specific gravity seem to have affected the fry a little 

 less than the eggs, possibly because the fry at the end of April did not consist exclusively 

 of larvae and as a consequence had become a little more active. 



These variations in tlie vertical distribution of eggs and pelagic fry, are very 

 important if we wish to understand the effects, which the horizontal movements of the 

 water layers exercise upon these organisms. 



Hydrographical observations show, that in these fjords those waterlayers, whore 

 eggs and fry were found, are subject to strong and quick changes and that these changes 

 are intimately connected with the strong Baltic current running past the coast of 

 Southern Norway ^ 



These changes are especially great and quick in the upper 30 — 40 metres. Direct 

 current measurements and numerous direct observations of the currents show that the 

 waterlayers are moving now in and now out of the fjords. The upper part of the 

 water as a rule moves outwards with considerable speed (in the S0ndeled-Fjord for 

 example a speed of 20—30 cm. sec. has been observed). The depth of this outgoing 



^ In July 1906 the coast current outside Ris0r was measured from the Michael Sars. The surface 

 layers possessed an average westward speed of ca. 80 cms. pr. second. (30 — 40 miles in the 24 houi-s)% 

 Even at 100 m. depth the current was still S cm. pr. sec, W, S,W, 



