SEA-FISHERIES LABORATORY 



215 



Larvae * 



liberated 





20 Hauls 

 each time 



Cod 

 eggs 



Cod 

 eggs 

 last 

 stage 



Cod 

 larvae 



Size of 

 larvae 



Date 



Millions 



Date 











4/4/05 



about 7 





28/3-29/3/05 



1840 



64 



154 



3-5 mm 



7/4/05 



„ 8 





12/4-13/4/05 



2201 



76 



83 



3*5-5 mm 



10/4/05 



„ 10 





29/4-2/5/05 



2134 



18 



37 



3-5-8 mm 



19/4/05 



,, 8 





15/5-16/5/05 



1075 



22 



44 



2-10 mm 



It will be observed that the liberation of 33 millions 

 of cod larvae produced no effect which could be recognised 

 in the numbers caught. The totals from the hauls show 

 that eggs were constantly spawned and hatched. But 

 the relation between eggs and larvae is never influenced 

 in the favour of larvae. For instance, notwithstanding 

 that more than 20 millions were liberated between the 

 first and second investigations, and that 10 millions were 

 liberated even two days previous to the second investiga- 

 tion, the number of larvae constantly decreased as did 

 the number of eggs in the last stage. On the fourth 

 examination the number of eggs in the last stage as well 

 as of larvae, again slightly increased. 



A decrease in the number of larvae is naturally to be 

 expected with the advancing season. But this decrease 

 and the final slight rise is also explained by a consider- 

 ation of the hydrographical changes which took place at 

 the time of the investigations. 



It will easily be understood that these small recently- 

 hatched cod larvae which are liberated in the fiords are 

 freely exposed to the movements of the water. During 

 the many weeks (they rarely appear at the bottom before 

 June-July) in which they are leading a pelagic life in 

 * Larvae from the Flodevigen hatchery, ready for liberation, 



measure (preserved in formalin, same as the captured larvae) from 



3-5 to 4*5 mm. 



