CHAPTER XVI 

 DISPERSION OF FRESH-WATER FISHES* 



ISPERSION of Fishes. The methods of dispersion of 

 fishes may be considered apart from the broader topic 

 of distribution or the final results of such dispersion. 

 In this discussion we are mainly concerned with the fresh-water 

 fishes, as the methods of distribution of marine fishes through 

 marine currents and by continuity of shore and water ways 

 are all relatively simple. 



The Problem of Oatka Creek. When I was a boy and went 

 fishing in the brooks of western New York, I noticed that 

 the different streams did not always have the same kinds of 

 fishes in them. Two streams in particular in Wyoming County, 

 not far from my father's farm, engaged in this respect my special 

 attention. Their sources are not far apart, and they flow in 

 opposite directions, on opposite sides of a low ridge an old 

 glacial moraine, something more than a mile across. The Oatka 

 Creek flows northward from this ridge, while the East Coy runs 

 toward the southeast on the other side of it, both flowing ulti- 

 mately into the same river, the Genesee. 



It does not require a very careful observer to see that in 

 these two streams the fishes are not quite the same. The 

 streams themselves are similar enough. In each the waters are 

 clear and fed by springs. Each flows over gravel and clay, 

 through alluvial meadows, in many windings, and with elms 

 and alders "in all its elbows." In both streams we were sure 

 of finding trout, f and in one of them the trout are still abun- 

 dant. In both we used to catch the brook chub,t or, as we 



* This chapter and the next are in substance reprinted from an essay pub- 

 lished by the present writer in a volume called Science Sketches. A. C. Mc- 

 Clurg & Co., Chicago. 



t Sak-elinus fontinalis Mitchill. 



J Semotilus atromaculatus Mitchill. 



282 



