Biological Survey — Erie-Niagara Watershed 229 



taken over a three months period in many types of streams. How- 

 ever the general tendencies are somewhat similar though the actual 

 figures vary considerably. For instance, 83 per cent of the food 

 found in the above mentioned twelve trout was aquatic and 17 

 per cent terrestrial in origin. This year of the 147 stomachs 56.66 

 per cent of the food was aquatic and the remaining 43.34 per cent 

 terrestrial in origin. Crayfish and shrimps were abundant in the 

 stream (Newfield creek) studied last year and formed 32 per cent 

 of the food consumed by the trout taken there. This class of food 

 formed only 0.72 per cent of consumed foods found in trout this 

 year and were generally quite unavailable forming only 0.2 per 

 cent of all available foods. 



From both seasons' work it is evident that trout consume to 

 the greatest extent those foods which are the most numerous. 

 They are opportunists like most organisms and eat what they find 

 on hand at the moment. The practical applications of this work 

 will lie in feeding trout upon these natural foods and determining 

 the relative amounts of each necessary to produce so many pounds 

 of fish. Then by determining quantitatively and qualitatively the 

 amount and kinds of food available in any selected stream, a 

 stocking policy can be developed to suit the food conditions in that 

 stream. 



Available Fish Food of Submerged Plant Beds. — In Table 7 

 will be found the combined results of two season's work upon the 

 productivity of plant beds. Three additional types were studied 

 this year; namely, Curly Pondweed {Potamogefon Crispus), water 

 moss (Fonfinalis) and a mixed bed of water moss and an alga, 

 Cladophora. It is to be remembered that only one unit area study 

 has been made in each type and these figures must not be con- 

 sidered as average. Much more work is necessary upon this 

 problem before any true evaluation of plant beds in trout streams 

 may be attained. 



Of the new types of plant beds studied this year, the Curly 

 Pondweed was the most productive and gave a weight of 5.85 

 grams (Table 7) of available fish food. The mixed bed of 

 Clado]^hora and Fontinalis produced 4.15 grams and the Fontinalis 

 alone, 3.4 grams per unit area. 



