The ProductivUy of J-'ish Tood hi Oneida Lake 2\y 



Some years ago, lM)rl)es ('<S,S, p. 5; 'o,^, |>. .V') examined the 

 stomach of two Pike Perch (Slirjoslcdioii vilrcum) from 

 Peoria Lake, Ilk, and found 10 specimens of (iizzard Shad 

 (Dorosoiua ccpediaunm) in one Pike Perch and 7 specimens 

 in another. These lish were from 3 to 4 inclies loni(. I'orbes 

 estimated that a Pike J'erch coukl not thrive on less than three 

 full m^eals a week averaging 5 small lish for a meal. Assuming 

 that the Pike Perch feeds for 40 weeks of the year, Forbes 

 estimated, on the above basis, that the Pike Perch eats 600 

 Gizzard Shad in the course of a year. This would mean that 

 100 Pike Perch, in a year's time, would consume 60,000 Giz- 

 zard Shad. The data upon which this estimate is based is 

 quite insufficient but indicates in a measure the number of 

 small lish that are necessary to support a large community 

 of a predacious fish like the Pike Perch. 



During the 1917 field work on Oneida Lake a number of 

 Pike Perch were collected in trap nets of which 3 out of 15 

 specimens examined contained fish in the stomach. One (20 

 inches long) had a Pumpkinseed 4 inches long (No. 1252); 

 another (13 inches long) had 4 small fish i^A inches long, 

 partly macerated; and a third (20 inches long) had one fish 

 nearly 4 inches long, partly macerated and unidentifiable 

 (No. 1229). From these examinations it would appear that 

 these Oneida Lake Pike Perch did not use as many small fish 

 for a meal as did Illinois specimens. As Forbes does not 

 give the size of the Pike Perch examined it is possible that 

 they might have been larger individuals than the Oneida Lake 

 speciniens examined. On the basis of the average food of the 

 Oneida Lake Pike Perch examined, 2 small fish per stomach, 

 using the feeding time indicated by Forbes, 40 weeks, and 

 three meals a week of 2 fish each, we calculate that a single 

 Pike Perch, of the average size of 17 inches long, will con- 

 sume 240 small fish in a year. On this basis 100 Pike Perch 

 will eat 24,000 small fish each year. Forbes' estimate of 6,000 

 food fish per year 100 Pike Perch w^ill consume 60,000 small 

 fish in the course of a year. On the basis of Riddle's ('09, 

 p. 450) conclusion that the digestive powers are reduced one- 

 third between November and March, these figures would be 



