habitat preferences and be influenced by different 

 specific environmental factors. For example, the 

 rock bass and the stonecathad very similar general 

 patterns of distribution, figs. 12 and 13; but the 

 lock bass inhabited deep, shaded pools and the 

 stonecat swift, rocky areas, fig. 25. 



It was usually difficult to distinguish the 

 factors that actually defined the habitat for each 

 species. Stream gradient, amount of shaded water 

 surface, dominant bottom materials, and the use of 

 surrounding lands appeared to influence the dis- 

 tribution of Jordan Creek fishes. But it should be 

 kept in mind that the fishes were actually in- 

 fluenced by more specific environmental factors. 

 The abundance of the bluntnose minnow, for 

 example, varied inversely with the stream gradient 

 but its distribution may actually have been governed 

 by some more definite factor determined by stream 

 gradient, such as velocity of flow, size of pools, 

 steepness of riffles, kinds of bottom materials, or 

 the associated food organisms. 



Summary 



1. The fish population in a continuous section 

 of Jordan Creek was censused with an electric 

 shocker to form a basis for further investigation of 

 the fishes of this small, warm-water stream. 



2. The 4-mile study section was separated in- 

 to eight divisions, each approximately one-half 

 mile in length. The lower four divisions were in a 

 rough, wooded area. Here the stream was composed 

 of short, hard-bottomed pools and steep riffles. 

 The four divisions above this wooded area were in 

 open, sunny, farm and pasture land. Here the 

 stream gradient was low, resulting in long, slow- 

 flowing pools. 



3. In the eight divisions of the study area, 

 the numbers and weights of fish taken were 

 tabulated for each species and for each family of 

 fishes. Particular attention was given the relation- 

 ship between the distribution of the fishes and the 

 characteristics of the habitat. 



4. Forty species of fishes comprised the 

 population. The minnows made up 75 per cent of 

 the total number and 38 per cent of the total weight 

 of all fishes. Sunfishes were second and suckers 

 were third in total weight. By number the stone- 

 loller was the most abundant species and by 

 weight it was second to the hog sucker. 



5. The distribution of species appeared to be 

 strongly influenced by four primary factors of the 

 habitat: stream gradient, shading of water surface. 



dominant bottom materials, and use of sur- 

 rounding land. 



6. The smallmouth black bass, the favorite 

 fish with Jordan Creek anglers, had a distribution 

 by weight similar to that of the hog sucker. There 

 was a direct correlation in weight between bass 

 and suckers in individual pools and an inverse 

 relationship in weight between bass and minnows. 



7. Certain species (rock bass, stonecat) were 

 found only in the wooded area, with a high gradient, 

 whereas others (largemouth black bass, sand 

 shiner) were abundant only in the slow- flowing 

 pools of the upper, open area. 



Literature Cited 



American Fisheries Society 



1948. A list of common and scientific names 

 of the better known fishes of the United 

 States and Canada. Am. Fish. Soc. 

 Spec. Pub. 1. 45 pp. 



i 



Forbes, Stephen Alfred, and Robert Earl Richardson 

 1920. The fishes of Illinois. (Second ed.) 

 Illinois Natural History Survey, Urbana. 

 cxxxvi + 357 pp. 



Funk, John L. 



1949. Wider application of the electrical 



method of collecting fish. Am. Fish. ■ 

 Soc. Trans, for 1947, 77:49-60. 



Gerking, Shelby D. 



1945. The distribution of the fishes of 

 Indiana. Ind. Dept. Cons, and Ind. 

 Univ. Invest. Ind. Lakes and Streams 



3(1):1-137. 



Gerking, Shelby D. 



1949. Characteristics of stream fish popu- 

 lations. Ind. Dept. Cons, and Ind. 

 Univ. Invest. Ind. Lakes and Streams 

 3(7):283-309. 



Hubbs, Carl L., and Karl F. Lagler 



1947. Fish of the Great Lakes region. 



Cranbrook Inst. Sci. Bui. 26. xi + 186 pp. 



Moore, Geo. A., Harold R. Pollock, and Donna Lima 

 1950. The visual cells of Ericymba buccata 

 (Cope). Joui. Compar. Neurol. 93(2) 

 289-95. 



i 



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