228 



BUIvI/ETlN OF THE BUREAU OI? FISHERIES. 



spondingly numerous. They have eaten some of every kind of nymph listed, but their 

 preference seemed to be for the damselflies rather than for the dragonflies, if we may 

 judge by the numbers consumed. At all events, it can easily be seen that odonate 

 nymphs are more toothsome to them than any other single article of diet. 



The dragonfly nymphs recorded up to the present time are mostly lyibellulides, and 

 it is generally stated that gomphine nymphs escape the fish by burrowing in the sand, the 

 mud, or the accumulated debris of the bottom. But even this burrowing habit does not 

 save them from some fish. Of three spoonbill cats, Polyodon spathula, taken at Keokuk 

 in May, 191 6, 40 per cent of the stomach contents of one fish consisted of nymphs of 

 Gomphus notatus. The second fish's stomach contained i Gomphus vastus nymph and i 

 Enallagma nymph, constituting 10 per cent of the food; the third stomach contained i 

 Gomphus vastus nymph, 25 per cent of the food. Of three moon-eye herrings, Hiodon 

 alosoides, one taken March 24, 1916, near Hamilton, 111., and the other two in June at 

 Keokuk, Iowa, each contained a full-grov/n gomphine nymph and nothing else. A river 

 drum, Aplodinotus grunniens, taken at Keokuk in June, contained a single gomphine 

 nymph, constituting 60 per cent of its food. 



Evidence from the fishponds themselves will be more convincing than that from 

 rivers, streams, or lakes, and fortunately there is an abundance of evidence from this 

 very source which furnishes just the proof desired. During the year from June, 191 6, to 

 June, 1 91 7, H. E. Schradieck, an employee of the Bureau of Fisheries, v/as engaged in 

 examining the food of the fishes in the very series of ponds (series D) here considered. 

 Permission has been granted to select from his manuscript records the data relating to 

 odonate food, and these data have been arranged in the following table : 



Food of Fishks from Ponds in Seriks D, Fairport, Iowa, Examined by H. C. Schradieck. 



Kind of fish. 



jer of fish ex- 

 amined. 



from which 

 taken. 



tnes in length. || 



ige length. 11 



Der containing 

 isel nymphs. 



jer containing 

 asel imagos. 



jer containing 

 ;on nymphs. 



0 

 0 



J| 



ft 



ite food, 75 to 

 ) per cent. 



,ge per cent 

 matefood.o 



ite eggs. 





s 



Ti 



a 





> 



Numt 

 dam 





as 



g 



g 



f 



§ 







0 



Ph 











0 





0 









Mm. 



Mm. 



















144 

 136 



3 



16 



so 



45 

 SI 



2 



38 

 18 



24 



8 



38 



68.5 









los 

 t6 



40 





29 



62 









3 



92 

 _8 



16 





0 



0 





0 









103 





20 



42 

 51 



29 



0 







4 



34 





Ictiobus bubalis: Buffalofish 



7 



60 



33 





0 



0 





X 









73 



















Ictiobus bubahs: BufTalofish 



350 



S&7 







0 





0 



0 





0 







8 



27 





18 





78 



14 



46 



68.5 

 34 





Eupomotis gibbosus: Common sunfish 



173 



16 B 



64 



45 



25 



8 







0 







143 



8 



23 



38 



30 



S 



0 









41 





Ictalurus pimctatus: Channel cat 



5 



9 





9 





0 



0 











Ictalurus ptmctatus: Channel cat 



21 



9 



45 



70 























95 

















<i This average includes only the fish that had eaten odonate food. 



