Biological Survey — Oswego Watershed 



197 



Comparison of Quality of Food in Stream and Pool Bot= 

 toms.— By referring to Table 3, it is seen that 36.9% of the 6,277 

 stream bottom animals taken were mayfly nymphs, while in pool 

 bottoms they constituted 41.24% of the 565 animals collected. 

 Whereas the per cent of mayfly nymphs in rapid water bottoms 

 was 36.9% as compared to 41.24% in pool bottoms, it must be 

 kept in mind that they constituted the largest single food element 

 taken in stream bottoms, while in pool bottoms they occurred 

 second to fly larvae and pupae, showing a decided preference for 

 lotic water. Stonefly nymphs, caddisfly larvae and pupae, beetle 

 larvae and adults, crayfish and shrimps (Crustacea), snails and 

 clams (Mollusca) were found in greater numbers in rapid water 



Table 3. — Showing Comparison of Available Aquatic Fish Food from Bottoms 

 in Rapid Water and in Pool Bottoms. 

 (Given in numbers and per cent by order) 



ORDER 



Rapid water 

 bottoms 



Number Per cent 



Pool bottoms 



Number Per cent 



Mayfly nymphs 



Stonefly nymphs 



Caddisfly, larvae and pupae 



Beetle, larvae and pupae 



Fly larvae and pupae 



Sialis larvae et al. (Neuroptera) 



Dragonfly nymphs and damselfly nymphs 



Crayfish and shrimps 



Snails and clams 



Miscellaneous 



Totals 



2,316 



921 



1,335 



476 



869 



58 



8 



235 



15 



44 



36.90 



14.67 



21.27 



7.58 



13.84 



.92 



.13 



3.74 



.24 



.7 



233 



23 



7 



15 



264 



12 



3 



1 



1 



6 



41.24 



4.07 



1.24 



2.65 



46.73 



2.12 



.53 



.17 



.17 



1.06 



6,277 99 



565 



bottoms. Sialis larvae (Neuroptera), dragonfly and damselfly 

 nymphs showed a preference for the quieter pool waters. 



Terrestrial and Other Food Animals Falling Into Streams. — 



For this class of food material the name "drift food" is pro- 

 posed, a term including all forms of available food, both plant and 

 animal, which may be carried by a current of water in a stream. 



Drift food was collected from streams of various types and 

 widths in different localities in an effort to find out the relative 

 amounts available under different conditions and widths of 

 streams. It has long been known that terrestrial insects and other 

 food animals accidentally falling into the water furnish abundant 

 food for trout, though the relative amounts of such food and the 

 types of stream environment which furnish the greatest amounts 

 of such food have never been known. 



