SMOLTS 5 



instance, I have two smolts which were reared at 

 the Duke of Kichmond and Gordon's ponds near 

 Fochabers at the mouth of the Spey, which are of 

 precisely the same age, viz. , twenty-one months. One 

 is fully eight inches in length, while the other is only 

 four inches. Under natural conditions experience 

 shows that it is well-nigh impossible to find a salmon 

 smolt of eight inches even at twenty-six months. 

 The smolt of the sea trout may occasionally be found 

 of this size, but not that of the salmon. The reason 

 for the greater size of the sea trout is simply that 

 this fish has a much more estuarial habit, and after 

 descent of the fresh water continues to feed and live 

 and apparently to move up and down in the tidal 

 waters of estuaries. Many common brown trout are 

 to be found under precisely similar conditions and 

 feeding on a purely marine diet ; in the estuary of 

 the Tay near the Tay Bridge I have found large 

 silvery common brown trout with freshly swallowed 

 herring as well as much digested herring in their 

 stomachs and intestines. Yet we must not too 

 hastily believe that we see in such instances as 

 these the cause of the seaward migration of the 

 salmon. In spite of the fact that the eggs of the 

 salmon can only live and develop in fresh water, 

 there are many who consider that the salmon and 

 indeed all salmonids are originally of marine origin. 

 Mr. Boulenger, whose word on such matters is im- 

 portant, points out, in his chapter on the salmon 

 family in the Fishing volume of the Country Life i 

 Library, that " the overwhelming majority of the 

 members of the sub-order of which the salmonids 



