100 American Fisheries Society 



edge of what are appropriate breeding conditions ; in the 

 case of the wall-eyed pike we are, I believe, still quite 

 ignorant. It seems to me useless to introduce the fry 

 into waters in which suitable breeding conditions are not 

 known to exist. We need more knowledge. In the ab- 

 sence of this, it is best to plant only in waters in which 

 the fish are known to be already breeding, and to intro- 

 duce the young, if possible, on the breeding grounds. 

 Small-mouthed bass require clear water and gravel bot- 

 tom for breeding. Large-mouthed bass prefer plant- 

 grown bottom and are more tolerant of turbid water. 

 Suckers require running water and gravel bottom. It is 

 unwise to introduce any of these forms into waters lack- 

 ing in the conditions peculiar to its breeding activities. 

 What is true of these species is equally true of others. 



2. Preservation of Breeding Grounds. The ditching of 

 streams and the lowering of lake levels by this or other 

 means need not seriously affect the food supply of many 

 fishes whose breeding grounds it destroys. The common 

 sucker, red-horse, the stone-roller and several species of 

 valuable bait minnows lay their eggs or build their nests 

 on the ripples of the smaller streams. Ditching such a 

 stream destroys these breeding grounds. They may be 

 restored by the meandering of the stream which forms 

 new ripples by depositing in its bed materials eroded 

 from its banks. But in the meantime the increase of 

 suckers or bait minnows may have been seriously 

 checked. If the stream is kept straight by repeated ditch- 

 ing these fish may disappear from it. 



Where lake levels are lowered the breeding grounds 

 of the majority of fishes may be destroyed. The pike 

 lays its eggs in the marshes or on the shallowest weed- 

 grown bottom, often on over-flowed meadows. The basses 

 and sunfishes and the bullheads build their nests on the 

 shoals in water usually not over two feet deep. The 

 blunt-nosed minnow, food for the large-mouthed bass 

 and pike, the Johnny-darter and the miller's thumb, lay 

 their eggs under stones very near the shore. When the 

 shoals are laid bare the breeding grounds of all these 



