ON SALMON. 



1909. 



35 



A close examination of these tables shows that the age of the smolts at 

 migration varies between two and five winters. In the south the smolts 

 are generally young, but the farther north we go the more pronounced is 

 the tendency for the fish to remain longer in the river before migration. 

 This is clearly seen from a comparison of the percentage of the different year- 

 classes, and we also find that in both tables the main features are identical. 



It will be remembered that it was previously pointed out that a direct 

 examination of fish caught in the rivers in the same districts (see p. 31) 

 showed that the river life tended to lengthen as we proceeded northwards, 

 and we have now been able to confirm and strengthen this theory by other 

 methods of investigation. 



(b.) The Length of the Salmon's Life after Migration. 



The two following tables show in condensed form the results of my 

 analysis of the salmon and grilse caught in 1908 and 1909 : 



1908. 



1909. 



32 



