CYPEINUS THE CARP 109 



lb. It is shown also that catfish gradually increased from 700,- 

 000 to 990,000 lb between 1894 and 1903; that crappie in- 

 creased from 138,000 to 210,000 lb; that sunfish increased from 

 175,000 to 507,000 lb between 1894 and 1899, falling off some- 

 what in 1903; and that suckers, although falling off from 155,000 

 to 67,000 lb between 1894 and 1899, rose again to 199,999 lb in 

 1903. The sole important commercial species that have fallen 

 off steadily since 1894 are buffalo and drum, the first declining 

 from 3y$ million pounds to about half that amount in 1903; 

 and drum from 348,000 to less than 100,000 ib in the year last 

 mentioned. If these records show anything at all it would 

 seem to be that the competition of the carp as spawn-eater and 

 water-soiler has not seriously affected many of our Illinois 

 River species. It is by no means improbable that causes entirely 

 apart from depredations and competition of carp may have 

 had a large influence in producing the recent decrease of buffalo 

 and drum. Among such causes may be mentioned increased 

 contamination of waters from municipal and industrial sources; 

 the obliteration, by drainage and diking, of backwaters used 

 as spawning grounds; and the increased rapidity of run-off 

 from the prairie and upland, as a result of tiling and the cutting 

 of the forests, affecting the extent and duration of the spawning 

 havens afforded by both swampy areas and small streams. To 

 these causes is to be assigned the decrease and approximate dis- 

 appearance of such minor species as pickerel and lake sturgeon, 

 which were never very abundant in the rivers in question, and 

 which began to fall off in numbers long before the carp entered 

 the field. 



It is not denied that carp will eat fish spawn; but it has not 

 yet been shown that they seek out spawn for the purpose of 

 consuming it. Black bass, crappie, and sunfish are doubtless 

 able to defend their nests against carp in any case. Certainly 

 the devouring of spawn has not affected the multiplication, as 

 shown by the output, of any of these three species, or of suckers 

 or catfish. That even a favorable effect of the multiplication 

 of the carp is not impossible is evident when it is remembered 

 that the myriads of young carp offer an almost inexhaustible 

 supply of food to the growing bass, crappies, and sunfish. The 

 drum and buffalo, which have decreased, are in their food habits 

 more directly in competition with the carp being chiefly bot- 

 tom feeders, utilizing mollusks, crustaceans, and insect larvae. 



