KNUT DAHL. 



According to this, the grilse caught in our waters during 

 summer would be ca. 4V4 years old, and the emigrating smolts 

 would thus, during 3 years in the ocean, develop into grilse. 



As I have mentioned above, our knowledge as to the growth 

 of young salmon must necessarily be to a large extent theore- 

 tical as long as we do not possess a sufficient number of young 

 specimens caught in the ocean. 



At present there is nothing to guarantee that the growth 

 in my aquaria has been quite normal. 



In order to judge, if other fish grow normally in the aquaria, 

 a sufficient supply of food granted, I have kept numbers of 

 young saithe (gadus virens) in a special tank. 



Their growth very well corresponded to the growth of the 

 same group of saithe in the sea, which from time to time 

 I easily caught for comparison. 



I do not however think, that these experiments with the 

 saithe justify any definite or final conclusion as to salmon. 

 Although I believe it to be probable, that really no large dis- 

 proportion exists between the growth of salmon in my aquaria 

 and in the sea. 



Chapter IV. . 

 On the growth and migrations of the trout. 



Like the salmon the trout of the sea ascend our rivers 

 to spawn. The trout run as a rule during late summer and 

 autumn. The ova are deposited in sandy places in the rivers. 

 Spawning occurs in most places in September — October. 



During winter the embryos develop. From the end of 

 February and towards the beginning of May the eggs hatch, 

 the ca. IV2 cms. long larvae emerging. Like the salmon they 

 are provided with a yolk-sack. Reposing among the gravel 

 of the bottom these larvæ during development use up the 



