562 BULLETIN OF THE BUREAU OF FISHERIES. 



Enemies. — From ova to senility the trout is subject to destruction by enemies. 

 These enemies are many and various, almost every zoological class, as well as some botan- 

 ical classes, being more or less represented. Bacterial, fungus, plasmodial, and para- 

 sitic diseases destroy them individually and epidemically. Nonparasitic, as well as 

 parasitic, worms and crustaceans and some insects are not infrequently fatal. Among 

 the vertebrates certain fishes, batrachians, reptiles, birds, and mammals can be men- 

 tioned. Of these, disregarding man, the fishes, not excepting the trout itself, are the 

 most serious. Under normal conditions these are some of nature's regulatory provisions 

 for maintaining those conditions. It is only when normal conditions are disturbed that 

 the enemies become generally harmful. 



The normal enemies of trout in the Rangeley waters have probably existed there 

 as long as the trout, and trout existed in normal numbers until civilization interfered 

 with the natural conditions. This interference augmented the numbers of some enemies 

 and diminished the number of others. The increase has been chiefly amongst the fishes, 

 the decrease among the birds and mammals. These natural enemies were not exclusively 

 enemies of the trout, but included other fishes, some of which were also trout enemies. 

 The additional enemies of the trout were not only direct but competitive enemies, 

 thus doubling their injurious effect. Thus, it may be seen that the decrease in birds 

 and mammals can not have compensated for the increase amongst the fish enemies. 



As has been seen in the faunal fist, the Rangeley Lakes were peculiarly free from 

 voracious fishes such as occur in most other trout waters, even in the neighboring river 

 basins, and some of which were found in the Androscoggin itself but which had no 

 natural access to the lakes. The principal resident enemies were suckers, chubs, eels, 

 and miller's thumbs, and while most of these were, in a way, naturally inimical, they 

 were to some extent directly and indirectly essential to the trout's existence. Eels seem 

 never to have been abundant, at least within the memory of man. The others were not 

 too abundant and were rendered so only by man's interference; that is, by the introduc- 

 tion of other more abundant and more easily obtainable food, thus making the original 

 food, the fishes named, unnecessary, as they were less apt to be eaten, and permitting 

 and promoting a greater multiplication of them. 



The directly inimical fishes that have been introduced into these waters are the 

 hompout, pickerel, and salmon. The effects of their accession are discussed in other 

 places in this paper. 



Of the natural enemies, the suckers are particularly harmful on the spawning beds 

 of trout, at least in some places, where they devour the eggs. 



The chub is to some extent harmful in that direction but more so in eating the fry, 

 and in this they are not restricted to naturally produced fry, as the following note indi- 

 cates, and which suggests the advisability of careful selection of the place of deposit for 

 artificially hatched trout. Regarding trout fry planted in Gull Pond, a letter from J. F. 

 Teach, to Maine Woods, dated September 25, 1903, contained the following: 



A few days ^o a number of trout fry from the Rangeley hatchery were put in here at my camp. The 

 next morning, observing these fish schooled in dense masses amongst the rocks on the water's edge, 

 Anthony Tibbetts, a guide, suggested catching a few chubs, of which there are multitudes in the pond, 

 in order to find certainly whether that fish devoured trout fry. Twenty-six chubs were taken out 

 accordingly, and every one, large and small, was packed to the lips with these trout. 



