Fish Culture in Inland Waters 279 



qualities, it does not signify that they are useless in the waters 

 inhabited. This is a matter that should also be determined. 



Natural Enemies of Fish, The so-called natural enemies of fish 

 are many and various, almost all zoological as well as some 

 botanical classes being more or less represented. Bacterial, fungous, 

 plasmodial and parasitic diseases destroy them individually and 

 epidemically. Non-parasitic, as well as parasitic worms and crusta- 

 ceans and some insects are not infrequently fatal. Among the 

 vertebrates certain fishes, batrachians, reptiles, birds and mammals 

 can be mentioned. Of these the predacious fishes are generally 

 regarded as the most serious. 



The normal enemies of any fish, under natural conditions in a 

 given body of water, have probably existed in normal numbers until 

 civilization interfered with natural conditions. These so-called 

 enemies are nature's balance wheels and it is only when normal 

 conditions are disturbed that those enemies of any fish become 

 generally haiTnful to it. Man has been the most destructive enemy 

 of fish in general. He has tampered with nature's machinery and 

 thrown it out of balance. The results have not always been cor- 

 rectly attributed to him, but rather laid at the door of some of the 

 alleged natural enemies. 



Man's interference may have increased the number of some 

 enemies and diminished the number of others. Some one natural 

 enemy of a given fish may prey upon other fishes as objects of his 

 " enmity." Some of the latter may also be enemies of the first 

 mentioned fish; sometimes direct enemies, that is, preying directly 

 upon the fish, or competitors for the food supply, or both. In the 

 latter case their injurious effects w'ould be doubled. So if man 

 should destroy the first mentioned enemy which serves as a check to 

 the undue increase of the others, the effect of an over-production of 

 the latter might be worse than before. 



There are many well-known instances of lakes and streams, which 

 have been stocked and restocked, but which have shown only brief 

 periods of satisfactory fishing, or none at all. In such instances the 

 most common remedy suggested for the condition has been the 

 extermination of one or another fish alleged to be an enemy of a 

 more highly esteemed fish. Whenever this has been accomplished 

 the desired or expected results have seldom been attained. 



Let us take a specific example. In the report upon the investiga- 

 tion of Lake George, elsewhere cited, Mr. Titcomb said : " within 

 the past twenty years at least thirteen distinct species of fish have 

 been planted in the waters of Lake George, and some of them in 

 very large numbers. There has been more special legislation for 

 the protection of the fishes of this lake than for any other body of 

 water within the State. Notwithstanding these facts, anglers report 

 that fishing conditions are not as good as they were some years ago, 

 and this appears to be especially true with reference to the lake 

 trout which may be regarded as the most important food fish 

 inhabiting- the lake." 



