March, 1963 Larimore & Smith: Fishes of Champaign County 



331 



Table 6. — Summary of collections and the number of species taken and recorded in Cham- 

 paign County by various collectors. Figures in parentheses indicate the numbers of collecting 

 stations. 



Occurrence 

 Category 



Number of 



species taken 



Number of previously 



unrecorded species taken .- 

 Number of previously 



recorded species retaken . 

 Number of previously 



recorded species not taken 



Total number of species 

 recorded (cumulative) 



Pre-Forbes & 



RiCHARDSOK 



(?) 



2 

 2 

 

 



Forbes & 



Richardson 



(48) 



63 



63 







2 



65 



Thompson 



& Hunt 



(126) 



74 



15 



59 



6 



80 



Larimore 



& Smith 



(152) 



74 

 10 

 64 

 16 



90 



in the county 60 or more years ago by 

 Forbes <S: Richardson or by Large. Two 

 species (X. atherinoides and Etheostoma 

 asprigene) taken by Forbes iSc Richardson, 

 but not by Thompson S: Hunt, were re- 

 discovered in the county in 1959. In all. 

 our collections represented 74 species, 64 

 of which had been previously reported 

 from Champaign County. The number of 

 collecting stations, number of species rep- 

 resented, and other data for each survey 

 are summarized in table 6. 



Summary of Changes Over 

 60- Year Period 



With full realization that fish popula- 

 tions may vary from one year to the next 

 and that comparison of results of three 

 widely spaced surveys could thus lead to 

 erroneous inferences, we believe that cer- 

 tain changes are demonstrable in the 

 Champaign County fish fauna over the 

 period of study reported here. (In this 

 paper, occurre?tce of a species is mea- 

 sured in relation to both the number of 

 localities or stations represented and the 

 number of drainages in which it was 

 found.) 



Evidence provided by the three surveys 

 reveals numerous changes in occurrence of 

 the fish fauna of the county. Of the 9 

 species added in 1959, at least 1 (Xotropis 

 li/trensis) appeared to have dispersed nat- 

 urally from the west, and 15 species, 

 which presumably had always been present 

 in the county, showed increases in abun- 

 dance and in number of drainages occu- 

 pied. These 16 species, the percentage of 



stations in Avhich they occurred, and the 

 number of drainage systems in which they 

 were found in each survey are listed in 

 table 7. Increased occurrence of these 16 

 species is suggested by scrutiny of the dis- 

 tribution maps, figs. 15—70, pages 362-75. 



On the basis of table 7, we could as- 

 sume that the large fishes (Pylodictis 

 olivaris, both species of Aioxostoma, Ali- 

 cropterus dolomieui, and Cxprinus carpio) 

 appeared to be more common in 1959 than 

 formerly because the modern collecting 

 apparatus used was more efficient than 

 seines in sampling deep pools. Improved 

 sampling methods could conceivably ex- 

 plain the slight increases in occurrence 

 shown for P. olivaris, the two species of 

 Moxostoma, and part of the increase in 

 occurrence shown for C. carpio, which is 

 easily shocked. 



It has been suggested that the mush- 

 rooming of Cyprinus carpio populations 

 within the past 30 years could be as- 

 sociated with the increased water pollution 

 in the same period. Perusal of the list of 

 species in table 7 reveals that the two 

 other pollution-tolerant fishes, Xotropis 

 umbratilis and Semotilus atromaculatus, 

 showed only modest increases in abun- 

 dance in this period but that their great 

 increase in abundance occurred much 

 earlier, some time between 1899 and 1928. 

 Moreover, gains of equal magnitude can 

 be observed in such pollution-intolerant 

 species as A\ riibellus and Hypentelitim 

 nigricans. 



Xotropis ruheUus, X . dorsalis, and X . 

 lutrensis are of particular interest because 



