334 



li.i.iNOis Natural History Survey Bulletin 



Vol. 28, Art. 2 



Table 9. — The number of species of fish taken and recorded in each of the six Champaign 

 County drainages and the number of species restricted to each of these drainages. 



it is indeed astounding that many of our 

 species were still present in the same 

 streams in 1959 and probably in approxi- 

 mately the same numbers then as 30 and 

 60 years previously. 



Results of an analysis of distribution of 

 species by drainage systems are sum- 

 marized in table 9. It will be seen that 

 Forbes 5c Richardson found the Salt Fork 

 drainage both the richest in number of 

 species, with 47, and the most distinctive, 

 with 9 species occurrinji: there exclusi\ely. 

 On the basis of these same criteria, they 

 found the Sangamon to be second, the 

 Middle Fork third, the Kaskaskia fourth, 

 and the Embarrass fifth. They made no 

 collections in the Little V^ermilion drain- 

 age. About 30 years later, Thompson & 

 Hunt found the Sangamon richest in spe- 

 cies and most distinctive, with a total of 

 50 species, 13 of which they diil not find 

 elsewhere. Other drainages ranked as fol- 

 lows: Salt Fork, Middle Fork, Kaskaskia, 

 Embarrass, and Little Vermilion. Our 

 findings were similar to those of Thomp- 

 son & Hunt, except that we found fewer 

 species restricted to a single drainage, and 

 no species restricted to the Embarrass 

 drainage. 



The most significant results of this 

 analysis, aside from the richness of the 

 fauna in each drainage, are the number 

 of species restricted to a drainage system. 

 More than 10 per cent of the 67 species 



in the Sangamon, almost 9 per cent of the 

 51 species in the Kaskaskia, almost 6 per 

 cent of the 55 species in the iVIiddle Fork, 

 roughly 5 per cent of the 20 species in 

 the Little Vermilion and of the 64 species 

 in the Salt Fork occurred only in their 

 respective drainages. None of the 36 

 species in the Embarrass occurred exclu- 

 sively in that drainage. This lack of spe- 

 cies distinctiveness for the Embarrass is 

 clearly evident on the distribution maps. 

 We can express distributional changes 

 by examining the drainage systems and 

 talhing the number of changes observable 

 when the Thompson & Hunt list of spe- 

 cies is compared with that compiled by 

 Forbes & Richardson and the Larimore & 

 Smith list of species is compared with that 

 compiled by Thompson & Hunt. A sum- 

 marv of these changes in presented in table 



10. ■ 



Table 10 indicates that the greatest 

 number of changes between the Forbes 

 ^' Richardson and the Thompson & Hunt 

 surveys occurred in the Middle Fork 

 drainage; 30 species were taken in one of 

 these surveys but not the other. The least 

 number of changes occurred in the Embar- 

 rass; 21 species were taken in one of these 

 surveys but not the other. No collections 

 were made in the Little Vermilion by 

 Forbes & Richardson. Within the approxi- 

 mately 30 years between the survey of 

 Forbes & Richardson and the survey of 



