330 



Illinois Natural History Survey Bulletin 



Vol. 28. Art. 2 



Increases in abundance appear to be sig- 

 nificant, as will be shown later. Thomp- 

 son & Hunt believed that their data in- 

 dicated a pronounced increase in the 

 abundance and distribution of Semotilus 

 atroniaculatus, Ericyniba bitccata, and 

 Micropterus dolomieui and suggested the 

 recent arrival in the county of Aplodi- 

 not us t/riinniens. 



A number of species showed apparent 

 decreases in abundance and distribution. 

 Some of the apparent decreases were 

 probably the result of cyclic changes in 

 populations; others probably represent 

 gradual disappearance of species. Thomp- 

 son & Hunt cited Hyhrxjtiathtis nuchalis 

 and Minytrema nielanups specifically and 

 noted that several other species seemed to 

 have declined in abundance. Comparison 

 of the distribution maps of Forbes 3: 

 Richardson and those of Thompson «S: 

 Hunt suggests that a reduction in numbers 

 of stations represented, in numbers of 

 drainages occupied, or in numbers of both, 

 also occurred in the following species: 

 Dorosoma cepedianum, Carpiodes cy- 

 prinus, C. velifer, and Moxostoma macro- 

 lepidotnm. However, in these species the 

 apparent decrease in abundance and dis- 

 tribution was probably not real, as there 

 was no evidence of their decrease from 



1928 to 1959. Moreover, all are large 

 fishes characteristic of deep pools and can 

 be easily missed when collecting is done 

 principally with a 10-foot minnow seine. 

 Another group of fishes, all of which are 

 creek species of small size, also showed 

 some reduction in numbers of stations or 

 drainages occupied, or both; but their ap- 

 parent reduction is assumed to have been 

 due to only a temporary decline in their 

 populations about 1928, as in 1959 none 

 showed evidence of reduced occurrence. 

 A third group of species, to be cited later, 

 showed striking decrease in abundance 

 and distribution between 1901 and 1928. 

 Their continued decline is documented by 

 more recent data. 



Tn\esti^ations Between 1929 and 1959 



Although some observations on fishes of 

 Champaign County were made between 



1929 and 1959 by various fishermen and 

 by personnel of the Illinois Natural His- 

 tory Survey and the University of Illinois, 

 no records of unusual interest were pub- 



lished. Several of Thompson &: Hunt's 

 records were cited by Luce (1933), who 

 utilized their collections from the head- 

 waters of the Kaskaskia in his study of 

 that river, and by O'Donnell (1935) in 

 his list of Illinois fishes. During the next 

 several years, material from Champaign 

 County was cited in several revisionary 

 studies, but none of these contributed new 

 distributional information. Although no 

 concerted efiFort was made to obtain col- 

 lections from the county, occasional field 

 work by two University of Illinois bi- 

 ologists, the late H. J. \'an Cleave and 

 H. H. Shoemaker, and by ecology classes 

 at the University contributed to the 

 knowledge of local fishes. Personnel of 

 the Natural History Survey, with head- 

 quarters in the center of the county, have 

 been alert to major changes in field popu- 

 lations and to alterations of habitats in 

 the area ; they have supplemented their 

 own observations through contacts with 

 fishermen and other local observers. 



Recent Survey Records 



Collections in 1959, and subsequently, 

 added 10 species to the known fauna of 

 Champaign County. Six of these [Amia 

 calva, Carassius auratus, Ictalurus nehu- 

 losus, Gambusia affinis, Roccus rnisslssip- 

 piensis, and Lepomis microlophus) are 

 known to be introduced species; three 

 {Lepisosteus osseuSj Noturus nocturnus, 

 and Percina sclera) are native and pre- 

 sumably were always present but were 

 overlooked by previous investigators ; one 

 {Notropis lutrensis) recently extended its 

 range eastward into Champaign County. 

 Our collections failed to reveal the pres- 

 ence of 1 1 species that were taken 30 

 years before by Thompson <Sc Hunt: 



Ictiobiis cyprinellus 



Ictiobus niger 



Hybopsis amblops 



Notropis amtiis 



\otropis boops 



Opsopoeodus emiliae 



Pimephales vigilax 



y oturus exilis 



Lepomis punctatus 



Rtheostoma chlorosomum 



Etheostoma gracile 

 Our collections also failed to include 

 three species {Ictiobus bubalus, Hybopsis 

 aestivalis, and }\ otropis heterolepis) taken 



