Fish Culture in Inland Waters 245 



should not be planted in brook trout waters. Because of these facts, 

 there are but few waters in Oneida County in which it is advisable 

 to plant rainbow trout." 



Concerning these same species, Embody says : " It is beheved that 

 of the three trout the brown trout is the most predacious and most 

 destructive of other fish and it is often stated that if a stream is 

 stocked with all three species, the browns will eventually exter- 

 minate the others. There are many streams where brook trout have 

 disappeared or become greatly reduced in numbers a few years 

 after the introduction of brown trout, but it has in no case been 

 proved that brown trout has caused the trouble. In fact there are 

 streams in Tompkins County where the brook trout and brown trout 

 occur apparently in equal numbers and have lived so for a number 

 of years. The Van Pelt Brook is perhaps the best example. This 

 matter is important enough to merit investigation. But until some- 

 thing more definite is known, it is well not to take any risks and 

 those who have studied the question deem it wise to keep the 

 coolest and purest streams for brook trout only, except in some 

 cases where rainbows may be advantageously introduced." 



Embody discusses also other stated habits of the brown and rain- 

 bow trouts, but it does not appear to have occurred to either 

 Clemens or Embodv or their predecessors in trout study, that real 

 incompatibility might be indirect rather than direct. Given three 

 individuals of the same size, one of each species, it may be a ques- 

 tion which is the most " predacious." From the statements of some 

 " authorities " it would appear that the advantage on the part of the 

 brown trout is due to the large size it attains (figure 21). Within its 

 natural growth limitations the size attained by any fish is in a 

 great measure dependent upon the quantity and quality of its food 

 supply. It is axiomatic that any stream can provide only a certain 

 amount of animal life. It has been claimed that the optimum of 

 favorable conditions for the three species in question differs some- 

 what, but these favorable conditions seem to overlap. Given a body 

 of water of optimum favorable conditions for one of the species but 

 which the other species nevertheless find congenial, might it not be 

 reasonable to expect that the first mentioned would ultimately crowd 

 out the others, not necessarily because it eats the other two forms 

 but because under optimum conditions it is a competitor of greater 

 capacity for the food supply? This might and probabh' would, in 

 some cases at least, react upon this fish itself in that during the period 

 of competition it is deprived of more or less food, but such reaction 

 would again be relieved if the fish were driven to eat the other 

 species, or if the other species were driven out. Then the natural 

 food supply could be expected to again increase to a maximum. 

 This situation might exist in connection with any one of the three 

 species mentioned. As Embody says, it merits investigation. How- 

 ever, to the present writer's mind the i^oint is that no more than one 

 species of the trouts should be planted in the same place. If a 

 stream possesses optimum brook trout conditions in one part, optimum 



