50 THE LIFE OF THE SALMON 



half years later off* an island on the coast more 

 than 90 miles distant from the river where it was 

 marked. It then weighed 18 lb. The unusual 

 size it had attained, coupled with the fact that it was 

 taken much nearer to rivers frequented by large fish 

 than the Figgen river, is at least suggestive of 

 the idea that the explanation of some rivers holding 

 fish of a much smaller average size than others may 

 be due to the fish seeking new rivers after they have 

 attained a certain size." 



In a chart showing migrations of salmon along the 

 coast of Scotland ^ are five lines indicating move- 

 ments of marked fish from the river Deveron, 

 which debouches on the southern shores of the 

 Moray Firth, to the east coast nets near Aberdeen. 

 Three of the five fish referred to were grilse, and in 

 each case this rather marked migration had been 

 made in four months or less. We have of course no 

 proof that those fish would not have travelled back 

 again, but I certainly consider such a return unlikely. 



The great majority of marked fish, grilse as well 

 as salmon, are found again in the rivers in which 

 they were marked, but such cases are suggestive of 

 the possibility referred to above. Yet after the con- 

 siderable amount of salmon marking which has now 

 been carried out in Scotland, it is natural to sup- 

 pose that if such a transference occurred frequently 

 in our rivers, more direct evidence of it would by 

 this time have been obtained. 



I have made reference to the large proportion of 



* Twenty-fourth Annual Report, Fishery Board for Scotland, 

 Part II. p. 69. 



