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4. The occurrence of cod eggs and pelagic fry. Their dependence upon 



hydrographical changes 



The occurrence of pelagic cod eggs and larvae in the fjords and the Skagerrack 

 was studied by making tow-nettings in the following manner. A small motor boat 

 dragged a circular net (1 m. diameter) of silk gauze for 5 minutes. The net was 

 buoyed up so as to fish within a certain distance of the surface. In this way the net 

 was towed at depths of 0, 2, 5, 10 and 20 meters i. The distance covered by the boat 

 at each townetting was by means of repeated experiments (taking crossbearings), proved 

 to be about 250 meters. The occurrence of postlarval cod was studied by means of 

 larger nets dragged for hours, and also by hand-nets. 



In 1904 the investigations were carried out in various localities in the Sendeled 

 and the Sandnes fjords and also the waters outside Kis0r. 



In 1905 a series of hauls of uniform duration with the 1 m. net was repeated 

 every fortnight at 7 stations, from the end of March to the middle of May. These 



7 stations (Sendeled Fjord 4 st., 

 Sandnes Fjord 2 st., Skagerrack 

 1 st.) are marked on the ad- 

 joined chart. At every station 

 hydrographical observations 

 were made each time. 



Later in the summer very 

 long hauls were made with a 

 circular net of 1-7 m. diameter 

 and a mesh 2 mm. 



The eggs and larvae 

 of the cod were found distri- 

 buted over the whole of the 

 area examined. In order to 

 give an idea of the occurrence 

 of cod eggs, the following catches obtained in 5 min. tow-nettings, may be quoted. 



On the 28. of April 1904 the following quantities of eggs were obtained at four stations 

 (a— d) situated between the stations II and IV Sendeled Fiord (see chart). 



Fig. 7. Chart showing position of tow-net and hydrographical 

 stations 1905. 



A very small percentage of these eggs were haddock eggs, the rest being cod eggs. 

 Even if we do not attach any special importance to a quantitative comparison 



* At some of the stations the depth did not allow deeper townettings. At other stations the depth 

 was so varying that it would be fatal to lower the townet more than 20 m. The results gained by 

 these townettings cannot of course claim any absolute accuracy. Their value in respect of quantity 

 must necessarily be relative. 



