194 



Conservation Department 



Fig. 1. — Galvanized square foot with sieve dipper 

 in use 



averages, at each station, whether or not the center of stream beds 

 contain more nutritive elements by weight, than is found at the 

 sides of stream beds. 



By comparing bottom studies made in streams under seven feet 

 in width with those above seven feet, it is evident that these small, 

 cold headwaters produce much more available fish food per unit 

 area than the larger, warmer main trunks. The average weight 

 of nutritive elements per square foot of bottom in streams under 

 seven feet is 2.36 grams, for those above seven feet it is 1.04 grams, 

 a difference of 1.32 grams; or in other words, streams below seven 

 feet in width probably produce more than twice the food by weight 

 per unit area of bottom. 



It is readily seen that the quantity of food organisms in 

 streams above 18 ft. in width decrease from the shore line to the 

 middle of the channel. At the fifteen foot (station 6) stream width 

 the three bottom catches weighed almost the same showing that the 

 food was fairly evenly distributed over the bottom, but still higher 

 in the center. At the eighteen foot stream width (stations 1, 3) 

 the food has materially decreased in the center of the stream bed 



