96 PACIFIC SALMON FISHERIES. 
In the present condition of sanitary science it is a comparatively 
easy matter to dispose of this filth by modern septic devices, and a 
number of cities are now disposing of their sewage in this manner. 
The irrigation ditch, a comparatively new product on this coast, 
while of great benefit in developing the arid lands in certain sections, 
as at present operated is a considerable menace to the salmon fisheries. 
But few ditches have screens at their head, and as a result many 
thousands of young salmon slowly making their way to their ocean 
home pass into and down these to an early doom. Every owner of 
such a ditch should be compelled to place at its head a screen with 
fine enough mesh to prevent absolutely ne passage through the 
same of even the tiniest baby salmon. 
Next to man and his methods the trout is undoubtedly one of the 
greatest enemies of the salmon. The Dolly Varden follow the salmon 
from the sea to the spawning beds, and when the eggs are extruded 
devour countless thousands of them. Many and many a time the 
writer has seen on the spawning beds female red salmon swimming 
around with a cloud of trout spread out behind like a fan, following 
her every movement, eagerly waiting for the moment when the eggs 
shall appear. 
In the summer, when the young are heading for the sea, the trout 
are lying in wait for them and again take their toll of countless 
thousands. 
Much is said by certain people of the ravages amongst the salmon 
of certain animals, as the seal, sea lion, bear, eagle, kingfisher, crane, 
duck, loon, and hawk. While in the aggregate the ravages of these 
animals are considerable, they are barely a drop in the bucket as 
compared with the direct or indirect ravages of man and his 
agencies. 
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