o 
Esk in Mid-Lothian, where, about fifty years ago, I have 
seen hundreds of true salmon wriggling up over the mill- 
weirs ; but there have been no such fish in that river for the 
last twenty years. 
Where have all the salmon and their progeny gone to, 
which frequented these rivers? The natural conclusion 
is, that rivers elsewhere have been resorted to. 
In some of the cases I have mentioned, and in multi- 
tudes of others, the probable cause of desertion, was the 
pollution of the streams by the establishment of paper-mills, 
dye-works, mining operations, and other manufactures, the 
refuse of which rendered the waters in these rivers unsuit- 
able for salmon life. 
Thus, about thirty years ago, shortly after the establish- 
ment of paper and woollen works in the upper parts of the 
river Whitadder, I used to see its lower parts covered 
with an oily scum and foam most destructive to fish. 
These remarks lead me to refer to other circumstances 
inimical to salmon when in our rivers. 
One is the formation of mill-dams or weirs, of such 
heights that, except in “spates” or heavy floods, the fish 
cannot reach any spawning grounds. In the cases of the 
Thames and of the Coquet, the English Fishery Inspectors, 
after careful investigation, gave it as their opinion that 
what originally caused desertion of salmon from both 
rivers, was the erection of impassable mill-dams and locks, 
which cut off access to spawning grounds. On the other 
hand, there are: rivers where salmon have become more 
plentiful, as in the Tyne; and the Chairman of the Fishery 
Conservators of that river informed me, that he attri- 
bute this increase chiefly to the removal of mill-dams and 
the formation of fish-passes. It seems a well-established 
fact that unless the fish find suitable ground for spawning 
