126 THE LIFE OF THE SALMON 
rivers for avery long period ; but it is quite possible, 
and I would venture to say in many cases very 
probable, that the cause of the late character has 
nothing whatever to do with the physical conditions 
of the rivers, but is purely the result of the influence 
of man in his treatment of the fisheries, and that as 
the treatment has continued on the same lines within 
the memory of man, so no one has ever known or 
heard of early runs of fish in those rivers. One might 
instance the case of the river Leven, which flows 
out of Loch Lomond into the Clyde at Dumbarton. 
This river has for a very long time been considered 
a late river, and there are old records of Dumbarton 
fisheries which point to this conclusion. A thriving 
dyeing and bleaching industry has long been estab- 
lished, gross pollution has resulted, and net fishing 
at the mouth of the river has been steadily carried 
on. But of late years an active and I may add a 
philanthropic angling association, which allows all 
anglers to participate in the sport which the loch 
affords, has done something to improve the general 
conditions and the stock of fish, with the result that 
early fish are appearing. In other cases where 
serious over-fishing has been allowed to continue 
rivers have naturally acquired a late character. With 
over-fishing, or other causes of reduction of breeding 
stock, the first class of fish to disappear is the spring 
run. We are therefore not safe in presuming that 
in all cases when we do not find a spring run the river 
isa late one. We must satisfy ourselves first that the 
river has every chance of bearing a full stock of fish. 
In Scotland—and concerning questions of tem- 
