SMOLTS 5 
instance, I have two smolts which were reared at 
the Duke of Richmond 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 
Library, that “the overwhelming majority of the 
members of the sub-order of which the salmonids 
