1 00 Kv. .•..•.•.■,•.•.•■.■.•■.•.•■.••.••!;:;•■.■.•;.•;.■::•. :•.'.•.•■.'.'.■.'. 



3 4 5 6 



DIVISION OF STUDY AREA 



Fig. 24. — Distribution (in per cent) of the four most numerous darters in the eight divisions of the 

 Jordan Creek study area, 1950. 



iscussion 



Jordan Creek was found to have an abundant 

 fish population, not only from the standpoint of 

 total number and weight but also from that of 

 variety of species. The abundance of fish was 

 probably related to the fertility of the lands drained 

 by this creek, whereas the number of species re- 

 flected the variation in the stream habitat. 



A natural division of the study area into 

 a rough, wooded area downstream and a flat to 

 rolling, open area upstream facilitated the relating 

 of fish distribution to ecological conditions. The 

 lower area showed more typical upstream charac- 

 teristics than did the upper area with its long, slow- 

 flowing pools. This reversal of upstream-down- 

 stream conditions tended to emphasize the specific 

 factors influencing fish distribution. 



Several species (rock bass, stonecat, brindled 

 madtom, and blackside darter) were restricted to 

 the lower area, whereas other species (largemouth 

 black bass, sand shiner, spotfin shiner, and star- 

 head topminnow) occurred abundantly only in the 

 upper area. The number and weight of the common 

 shiner decreased progressively upstream; the 

 number and weight of the silverjaw minnow de- 

 creased progressively downstream. The distribu- 

 tion of several species (white sucker, stoneroller, 

 bluegill, green sunfish, and yellow bullhead) seemed 

 to be influenced by specific habitats not restricted 

 to either the upper or lower areas. A few species 

 were represented by only one or two specimens and 

 were considered only temporary residents of 

 Jordan Creek. 



Species with similar general distribution 

 patterns in the study section may have different 



23 



