24 Conservation Department 



The factors are many and their interrelations are complex. How- 

 ever, it seems desirable to attempt some sort of an evaluation of 

 the trout streams in order to avoid the more obvious errors in 

 stocking that have been made in the past. 8ome of the factors 

 involved may be briefly discussed as follows: 



Area of Stream Available for Trout. — It is not an unwar- 

 ranted assumption to state that, all other things being equal, the 

 j)roductiveness of a stream varies directly with the foraging area, 

 which is practically that part of a stream inhabitable to trout. 

 An approximation of this area was calculated by finding the aver- 

 age width from a series of measurements made in different sections 

 and multiplying this by the length. For convenience in the final 

 calculation, this area was expressed in acres per mile. 



Abundance of Primary Food Organisms. — Collections of the 

 principle group of lourely aquatic food organisms w^ere made in 

 different sections of the various streams. It was then possible to 

 classify streams as: (1) Rich in food, (2) containing average 

 quantities and (3) poor in food. This does not seem to cover 

 the terrestrial forms which fall into the water, such as worms, 

 grasshoppers, bees, ants and others, sometimes constituting as 

 much as 50 per cent of the food of trout. There is some relation 

 between the width of the stream and the number of insects, etc., 

 falling in and hence this item would be rougldy covered in con- 

 sidering the area. 



Certain environmental factors w^ere found to be correlated with 

 the abundance of food organisms. They are named as follows in 

 the order of increasing richness : 



(1) A bottom of sand or hardpan without vegetation contained 

 very few food animals. 



(2) One of coarse to fine gravel was little better. 



(3) Muck or silt bottom with much organic debris seemed to be 

 provided with an average amount of food. 



(4) Bottom of flat rocks and rubble contained mayflies, stone- 

 flies, caddis worms, crayfish, and mau}^ others in great abundance. 



(5) A stream margined with watercress or a bottom with fre- 

 quent and dense clumps of moss, Fonfinalis, constituted the richest 

 of any environment encountered. Fresh-water shrimps of three 

 genera — Gammarus, Eucrangonyx and Hyalella; Oligochaete 

 worms, midge larvae, mayfly and stonefly nymphs and caddisfly 

 larvae were among the most abundant forms. 



Pool Conditions. — In the case of central New York trout 

 streams, it is well known to anglers that those having the largest 

 iiiiiiiix'i- of dee}) ])ools with suitable shelter, furnish the best fishing, 

 b()1li ill j)oint of numbers and size of fislies. Of course, sheltei" 

 is an im|)ortant factor in attracting fish, but shelter acting alone 

 could not account for the greater amount of fish flesh produced 

 in those streams. There must be some relation between the abun- 

 dance or accessibility of food and the type of ])ool, although it is 

 nol known wlial this is. Nevei'theless, we must consider the abun- 

 dance, tre(piency and tyi)es of ])0()ls in making our calcuhitions. 

 Tlie streams have been classified in this respect as follows: 



