AGE AND GROWTH OF SALMON. 139 



There is also a well-authenticated instance of a 

 smolt that was marked on its way to the sea, and 

 that, when taken the next year on its return from salt 

 water, weighed 20 lbs. It cannot for one moment 

 be taken for granted that all salmon grow at such a 

 rate ; but had this little fish, which was marked when 

 a smolt, continued to grow with the rapidity of its 

 grilse year, it would have attained a weight of 40 lbs. 

 under four years from the date of its birth. Of 

 course this estimate is made without taking into 

 consideration that the fish had spawned, in which 

 case it would take another year before it could put in 

 an appearance as a 40 lb. fish. It is very evident that 

 we could only in isolated cases ascertain the age 

 of salmon of such a heavy weight as 40 lbs., and 

 when we consider the infinitesimal number of 

 smolts that are marked, and also the very small 

 proportion of salmon that ever attain a weight of 

 40 lbs., the chances of ascertaining the age of even 

 marked fish of such a weight are very small 

 indeed, whilst to ascertain or even give an ap- 



