Tiffany. — The Gi::::ard Shad 



383 



known as Protococcales ; a number are desmids and diatoms; 

 and a few are filamentous. The number of any particular kind, 

 especially among the Protococcales, seems to depend directly 

 upon the richness of the plankton present. No attempt is made 

 in this paper to give the identification of the microscopic plants 

 and animals — a further study is necessary before such a report 

 can be made.* 



The following table gives in approximate percentages the 

 food of the gizzard shad in a comparative way for each locahty : 



Approximate Percentages of Kinds of Food in Gizzard Shad 



One of the outstanding features of the foregoing table is 

 the constancy in the percentage of microscopic plants found in 

 the fishes examined, regardless of locality or size within the 

 range of this study. The kinds of algae comprising the food 

 were not the same for different localities, and even for the same 

 locality differences were noted in fish collected in June and 

 August. This variation is doubtless due to the geographic dis- 

 tribution of the plants and to the fact that most algae have 

 rather definite seasonal cycles of vegetative development. But 

 the more or less constant percentage seems to indicate that the 

 gizzard shad is able to utilize a rather large variety of micro- 

 scopic plants. The writer hopes to be able to follow out some 

 of the seasonal changes for a given locality in the near future. 

 Another interesting observation is the comparative sameness 

 of diet of the fish throughout the period it is attaining a length 

 of seventy millimeters and even more. Many other fishes, like 



• A complete list of the algae determined in the food of the Gizzard Shad appeared 

 in the Ohio Journal of Science for February, 1921. 



