496 U. S. BUREAU OF FISHERIES 



The State authorities appear to be helpless in these matters, but an 

 enactment by the Federal Government could be maintained, as the 

 principle has been applied to fishery matters elsewhere, notably the 

 spring mackerel closed season for five years and the sponge law relat- 

 ing to the landing of undersized sponges taken from the grounds oft' 

 the Florida coast. 



Pollution of streams. — Next to the fishing operations of man, the 

 gravest danger to the salmon fisheries of the Pacific coast lies in the 

 pollution of the rivers which the salmon ascend for spawning purposes. 

 The salmon, both old and young, require pure cold water, and the 

 immense runs which have annualh'^ ascended the streams for many 

 years are doubtless due to the fact that such conditions have pre- 

 vailed in them. The large increase in the popidation of the coast 

 States within recent ,years, with the resulting increase of mills and 

 factories, has greatly increased the amount of sewage from cities and 

 towns and the waste of the manufacturing plants. Many of the 

 latter have also constructed dams without adequate fish w" ays, and 

 these also wreak great havoc to the industry by cutting the fish oft* 

 from the upper reaches of the rivers upon which constructed. 



The emptying of sewage into streams ought to be made a crime. 

 It is an exceedingly crude method of dealing with it, and, instead of 

 disposing of the filth, merely transfers it from one place to another, 

 making the water unfit for use at points farther downstream and 

 spreading diseases and death amongst not only the finny but also 

 human users of it. 



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 the 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 the passage through the same 

 of even the tiniest baby salmon. 



Animal 'enemies. — Next to man and his methods the trout is un- 

 doubtedly 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 Avait 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 sea!, sea Hon, bear, eagle, kingfisher, crane, 

 duck, loon, and hawk. While in the aggregate the ravages of these 

 animals are considerable, they are not a drop in the bucket as com- 

 pared with the direct or indirect ravages of man and his agencies. 



