300 



Illinois Natural History Surnlv Bulletin 



Vol. 28, Art. 2 



tion of some of tlu- difHcult specimens. 

 Dr. Horace W. Norton and Mr. Bud J. 

 Meatior }2;ave counsel and fiuidance in an- 

 alvzinji our data. Dr. Thurston E. Lar- 

 son, Dr. Russell T. Odell, Dr. Robert A. 

 Evers, and Mr. \\\ J. Roberts offered de- 

 tailed information relating to their par- 

 ticular specialties. 



The photographs were taken bv Mr. 

 ^Villiam E. Clark and Mr. Wihiier D. 

 Zehr; fig. 6 was drafted by Mrs. Alice 

 Ann Prickett; much of the drafting of 

 the distribution on maps was done by Mr. 

 Ralph G. Downer. 



We owe a special debt to Dr. George 

 W. Bennett for suggestions and encour- 

 agement throughout the investigation and 

 to Dr. Bennett and Dr. H. H. Ross for 

 critical perusal of our early manuscript. 

 We are indebted to Mr. James S. Avars 

 for his editing of the final manuscript. 



The Illinois State Department of Con- 

 servation co-operated in this study by sup- 

 porting part of the field work and labora- 

 tory analyses. 



METHODS AND EQUIPMENT 



Methods and equipment employed in 

 sampling stream fish populations should be 

 selected on the basis of the demands and 

 objectives of the study and the amount of 

 time and effort that can be expended in 

 making the collections. During each of 

 the surveys of the fishes of Champaign 

 County, the procedure was to visit well- 

 distributed sites, selected to yield a com- 

 prehensive picture oi the fishes of the 

 streams. Seines were used as standard 

 equipment in the first two investigations; 

 during the third survey both seines and 

 electrofishing ecpiipment were employed. 

 The total time spent procuring collections 

 may have doubled with each succeeding 

 survey. These changes in procedure and 

 intensity of collecting present difficulties 

 in comparing results of the three sur\eys. 

 In drawing conclusions, we have care- 

 fully weighed the difficulties inherent in a 

 study extending over more than half a 

 century. 



Forbes & Richardson Procedure 



Forbes c^ Richardson (^K)8) made 

 their collections by seining, presumably 

 with seines of various mesh sizes, at se- 

 lected sites throughout the county. As far 



as we know, these early investigators made 

 no attempt to do a uniform amount of 

 seining at each station or to determine the 

 relati\e abundance of the \arious species 

 found. The number of revisits, if any, 

 that they made to their stations cannot be 

 ascertained. According to Thompson & 

 Hunt ( I'^^^O: 16), the collections of Forbes 

 & Richardson spanned a 20-vear period : 

 1 in 1882. 3 in 1885. 1 in 18Q2, 2 in 1898, 

 22 in 1899, 3 in 1900. and 8 in 1901, giv- 

 ing a total of 40 collections from 40 sta- 

 tions. Apparently these counts were made 

 from the old accession catalogs and the 

 atlas of maps that accompanied Forbes & 

 Richardson's The Fishes of Illinois. They 

 do not agree with our calculations. Our 

 count of localities plotted by Forbes 



(1907) and b}- Forbes iSc Richardson 



(1908) and of localities represented by 

 specimens still extant at the Natural His- 

 tory Survey from early collections raises 

 the number of Champaign County locali- 

 ties sampled by Forbes & Richardson to 

 48, distributed by drainages as follows: 

 Salt Fork 27, Sangamon 10. Kaskaskia 5, 

 Embarrass 3, and Middle Fork 3. 



Thompson & Hunt Procedure 



Thompson .^ Hunt (1930:1-1—7) em- 

 ployed seines of certain lengths and mesh 

 sizes. They recorded the actual number 

 of fish taken at each collecting station and 

 the calculated number per 100 square 

 yards of area seined. In the words of 

 Thompson & Hunt (1930:5), "the gen- 

 eral methods emploved in the former sur- 

 vey have been applied intensively to a 

 small area. Champaign County, and use 

 has been made of special methods which 

 yield results more strictly quantitative." 

 Records show that 126 stations were sam- 

 pled in 1928 and that a few stations were 

 revisited in the spring of 1929. Of the 

 total number of collections. 132, Thomp- 

 son & Hunt (1930:14-7) made 127 with 

 a seine, 10 feet by 4 feet, having meshes 

 one-sixth inch square and 5 with a seine, 

 75 feet by 6 feet, having meshes 1 inch 

 square. Their 126 stations were distrib- 

 uted by drainages as follows: Salt Fork 

 48, Sangamon 31, Embarrass 19, Kaskas- 

 kia 15, Middle Fork 9, and Little Ver- 

 milion 4. Thompson & Hunt emphasized, 

 and demonstrated with amazing success, 

 the importance of skill and efficifncy in 



