The Producl'wity of Fish Food in Oneida Lake 2^ 



The dredging in deep water was difficult. Experiments were 

 first made in shallow water; the 16 inch dredge was dragged 

 for a distance of 48 inches, providing a square area of 168 

 scjuare inches (16x48), or the ecjuivalent of 48 of the 16 

 square inch shallow water units. Of course the error in this 

 was much greater than in the shallow water dredgings with 

 the Walker dipper, but a special effort was made to make the 

 work as accurate as possible. In shallow water there were a 

 large number of dredgings, in all 544, the large number reduc- 

 ing the error considerably and making the results fairly 

 reliable. In the deeper water only 18 dredgings were made so 

 that both the small number and the difficulty of taking an 

 accurately measured sample made the error much greater. 

 On the other hand the animals decline both in number of 

 species and in individuals, and probably in importance as fish 

 food, with depth, so that recognizing these limitations the cal- 

 culations have been tabulated and used as in shallower water. 



This material has been carefully examined quantitatively, 

 the groups represented in each station lot being sorted and 

 counted, a labor the monotony of which can be realized only 

 by those who have engaged in similar statistical work. The 

 sorting and enumeration of individuals was performed in glass 

 dishes about two inches in diameter. For this purpose the 

 glass dishes known as Syracuse watch glasses were used. A 

 hand lens of 5 and 10 diameters and a compound microscope 

 with powers up to 50 diameters were used in sorting the 

 material. When finally sorted and made ready for examina- 

 tion by specialists the collections occupied more than 1500 

 vials. All of the data supplied by the material has been plotted 

 on the quantitative tables in the body of this report. 



Petersen both counted and weighed the animals used for 

 his quantitative studies, giving " dried " and alcoholic weight 

 ('11, pp. 50-53). In the present report only the number of 

 animals per unit area has been used. It may be of value in 

 future investigations of this character not only to weigh the 

 animal matter but also to calculate the food value in terms of 

 proteid, fat, etc., as has been done by many European investi- 

 gators in marine studies (see Johnstone, '08, pp. 189-191). 



