42 



partly crayfishes, but chiefly the smaller kinds, known to zoolo- 

 gists as amphipods and isopods, and in common speech as 

 water wood-lice and brook shrimps. Aquatic insect larvae, 

 'especially those of day-flies, and small spiral-shelled moUusks 

 are eaten in about equal ratio. 



The two pike-perch or " ivall-eyed pike," are exclusively 

 piscivorous, if we may judge from twenty-six specimens whose 

 food I studied. More than a fourth of the fishes taken con- 

 sisted of the spiny-finned species, including eight per cent, of 

 catfishes, but nearly half were the common gizzard shad. 



We shall find accumulating evidence that this shad, not used 

 with us for food, is, notwithstanding, one of the most valuable 

 fishes in our streams. Nevertheless, not the slightest attention 

 is paid to its preservation, much less to its encouragement. 

 The fishermen commonly regard these fishes as a mere nui- 

 sance, and leave them to die on the bank by hundreds, rather 

 than take the trouble to return them to the water. They are a 

 very delicate species, and are easily killed by rough handling in 

 the seine, but the majority of those captured might be saved 

 with a little care. 



Their abundance as compared with some other species in 

 our rivers might seem to indicate that they are common enough 

 as it is. Few realize, however, the number of fishes needed to 

 feed a pike-perch to maturity. Two or three items from my 

 notes will furnish the basis for an intelligent estimate. 



From the stomach of a pike-perch caught in Peoria Lake, 

 October 27, 1878, I took ten well-preserved specimens of gizzard 

 shad, each from three to four inches long ; and from another I 

 took seven of the same species, none under four inches in length. 

 As the gizzard shad is a very thin, high fish, with a serrate 

 belly, these were as large as a pike-perch can well swallow ; 

 and we may safely suppose that not less than five of this shad 

 would make a full meal for that fish. The pike-perch is a very 

 active hunter, and it is not at all probable that one can live and 

 thrive on less than three such meals a week. The specimens 

 above mentioned were taken in cold autumn weather, when 

 most other fishes were eating but little ; but since fishes gen- 

 erally take relatively little food in winter, we will suppose that 



