364 REPORT OF THE FOREST, FISH AND GAME COMMISSIONER. 



supposed to be pure may prove to be unfit for fish transportation, and such 

 conditions are usually discovered when it is too late to save the fish. 



Pollution of Wafers 



The contamination of trout streams and rivers and lakes in which val- 

 uable fish would live if conditions were favorable is a grave cause of failures 

 in fish culture. Sawdust and other mill refuse, poisonous acids and alka- 

 lies from refineries and chemical works, sewage and the drainings from barn 

 yards are responsible for greater depletion of streams and more disease and 

 mortalit}^ among fishes than all other causes combined. 



Sawdust covers up the spawning grounds, spreads and accumulates on 

 the bottom, ferments and offers a lodging place for fungus to such an extent 

 that it makes a stream uninhabitable for any good fish. Acids and alkalies 

 have been known to kill all the trout that come in contact with them. 

 Sewage and the liquors running from barnyards have spread bacterial 

 diseases among brook trout and brown trout so extensively as to destroy 

 the entire brood stock of some of our most important stations. Sewage 

 is not only a common source of disease among trout, but it is also a menace 

 to the public health, and many serious epidemics are caused by allowing 

 it to escape in streams. 



Destruction of Spawning Grounds 



Sawdust is not the only deleterious substance affecting the spawning 

 beds of trout, shad and other choice species. Cinders and ashes dumped 

 from river steamers and other craft are working great injury to the natural 

 reproduction of fish. As a recent illustration of this evil may be cited the 

 filling up of the Little Channel, near Tivoli on the Hudson, where no spawn- 

 ing shad could be taken in 1907, and nets cannot even be used on account 

 of the abundance of cinders. 



Difficulties in Collecting Eggs 



The spawning season of most of the good species utilized in fish culture 

 occurs in the late fall and winter or very early in spring when storms are 



