Osburn. — Conditions Detrimental to Bass. 31 



thorn-headed worms, which they obtain from larger crus- 

 tacean food. (Wickliff, Transactions, Vol. L. p. 364-371 and 

 Turner and Kraatz Transactions, Vol. L. p. 372-380, have 

 shown how the type of the food varies in relation to the size 

 of the fish.) 



But it is not only the young fish that are affected by these 

 enemies. The adults may sometimes be heavily infested 

 with tape worms so that the intestine may be almost closed 

 by them.. Fluke worms may attack the liver and the coeca, 

 especially, to injure the fish and thorn-headed worms may 

 occur sometimes by the hundreds in the intestine and the 

 coeca. Fishes so parasitized usually show it by the gaunt 

 appearance, the absence of intestinal fat, the smaller size 

 of the reproductive organs, etc. It is not possible to esti- 

 mate with any degree of exactness the check which these 

 parasites produce on growth and reproduction and it prob- 

 ably varies greatly in different waters and in different sea- 

 sons, but it is undoubtedly important. It may not be possi- 

 ble to control parasitism in natural waters, but I shall have 

 something to say later concerning the control of parasitism 

 in hatcheries. Parasitic Crustacea and certain of the fluke 

 worms occur on the gills, but I have not found these numer- 

 ous enough on the basses to produce serious results. 



The natural enemies preying on the basses are many, 

 especially in their younger stages. The predaceous water 

 insects get some of them when they are very young, Pre- 

 daceous fishes take their toll and it is not a small one. I 

 have found young bass in the stomach contents of many fish- 

 es but especially in the yellow perch, the gars and the grass 

 pike. To a lesser extent I have found them in catfishes of 

 various species, the chubs, the crappies, the green sunflsh 

 and occasional others, while the larger bass do not hesitate 

 to make a meal of their younger kin at times. 



Frogs, snakes and turtles occasionally get the bass as a 

 part of their diet, though the bass is usually too quick for 

 such enemies. Various kinds of birds also take their toll of 

 the young bass, as is well known. The common tern is pro- 

 tected and there has been considerable discussion pro and 

 con as to the destructiveness of this bird on the game fishes. 

 This much has come under my own observation. The small, 

 barren Starve Island, near Put-in-Bay, Ohio, is inhabited by 

 large numbers of terns which breed there. I have been un- 

 able to find any young bass about this island in several sea- 

 sons, though the character of the bottom is suitable for 

 breeding purposes. Careful investigation of the food of 

 these birds may force us to include them among the un- 

 desirables. 



