16 New York State 



away and the area coming under the influence of this waste become 

 thereby barren of fish life. Plenty of evidence can be given to 

 prove that this occurs frequently, on streams of moderate or small 

 size. While such areas are to be found, the absence of fish life is in 

 fact not the most serious characteristic. In the adult condition the 

 fish are relatively large and as little susceptible to the effects of 

 pollution as any organisms which inhabit the water. Even though 

 they may be lacking from a given area, it \s often the case that they 

 have been driven away by adverse conditions, as well as directly 

 destroyed through poisonous substances. The net result of driving 

 fish out of water that might be made productive is quite as bad as 

 killing them in it. 



Chemical substances which are of such a character as to destroy 

 the life of the small organisms will eliminate from the territory 

 those things on which directly or indirectly the fish feeds, and with 

 the disappearance of its food the fish are forced to migrate or to 

 starve. They are quick to respond to such influence, as i& well 

 known to fishermen, for by thoroughly baiting a given area with 

 food, fish may be readily attracted into it and are, of course, also 

 sought in those places that are the best feeding grounds. Con- 

 versely, an area barren of life is not a satisfactory place io go fish- 

 ing. The absence of other forms of life is good evidence that the 

 fish will not, in general, be found there. Evidently, then, agencies 

 that tend to reduce a water area to a barren condition will be 

 promptly instrumental in driving away the fish that naturally con- 

 gregate in that territory. 



Pollution and Fish Propagation 



There is another way in which pollution of water very directly 

 and seriously affects its fish population, and that is in the influence 

 upon the propagation of the species. Fish deposit their eggs 

 variously, but, in general, at selected points in the stream bottom, 

 some species choosing one kind of environment and others selecting 

 another. Fish seek for this purpose a clean area of bottom, or 

 prepare it in definite fashion by brushing away the dirt from a 

 limited space which serves as a nest. If the waters are highly 

 polluted, the sediment which covers the bottom befouls the area 

 and reduces the free oxygen to low terms. As a result, a satisfac- 

 tory nest cannot be cleaned out, or, if it is, the adjacent decaying 

 materials still affect the water so unfavorably that the eggs cannot 

 live and the reproductive activities of the fish are seriously interfered 



