[eee ccl 
oy vas Sy We af 
Le 
RES SINE 
y, = 
Zion 
Se 
2 
fa 
Fig. 25-26.—Two species of fishes deci- 
mated because impoundments have de- 
stroyed many of their habitats. Circles, 
before 1905; dots, after 1950. 
5. 26. 4 — 
ETHEOSTOMA RY 
BLENNIOIDES MELLUCIDA eAEN \- 
Unknown Causes 
No single factor can be identified as the probable 
cause for the extirpation in Illinois of the muskellunge, 
which once occurred in extreme northern Illinois, and 
the stargazing darter, which once occurred in the 
lower Wabash River (Smith 1965). The decline 
of the lake sturgeon, blue sucker, and paddlefish 
is probably due to a combination of such factors as 
dams, silt, drainage of marginal lakes, pollution, and 
overexploitation. The decimation of the orangespotted 
sunfish, a species rather tolerant of silt and some pollu- 
tion, is inexplicable. 
So-called channel improvement through dredging 
and stream straightening destroys habitats over eX- 
tensive stretches of streams, but by itself it cannot be 
regarded as the principal cause for the decimation 
of any native fish. 
Summary of Factors Discussed 
The following tabulation lists the factors primarily 
responsible for the extirpation of 8, and the decima- 
tion of 60, native species of [linois fishes. 
Number of Number of 
species species 
extirpated decimated 
Silt 2 14 
Drainage 0 13 
Desiccation during drought 0 12 
Species interaction 2 7 
Pollution 2 5 
Dams and impoundments 0 4 
Temperature 0 il 
Unknown causes 2 4 
14 
LITERATURE CITED 
BAILEY, REEVE M., Chairman. 1970. A list of common an 
scientific names of fishes from the United States an 
Canada, 3rd ed. American Fisheries Society Speci: 
Publication 6. 150 p. 
Forpes, STEPHEN ALFRED, and RoBERT HARL RICHARDS 
[1908]. The fishes of Illinois. Illinois State Laborato) 
of Natural History [Urbana]. exxxi + 357 p. + separa 
atlas of 103 maps. p 
JorpAN, Davin S. 1878. A catalogue of the fishes of Tilino: 
Illinois State Laboratory of Natural History Bullet 
Gh (BY) Sexe | 
Larmmore, R. WELDoN, and PHILIP W. Sir. 1963. T 
fishes of Champaign County, Illinois, as affected by 
years of stream changes. Illinois Natural History 5 
vey Bulletin 28 (2) :299-382. 
1935. Annotated list of the fist 
Survey Bulle 
O’DonnELL, D. JOHN. 
of Illinois. Illinois Natural History 
20(5) :473-500. 
Pagh, LAWRENCE M., and RicHarp L. SmirH. 1970. Rec 
range adjustments and hybridization of Notropis wir 
sis and Notropis spilopterus jin Illinois. Illinois St 
Academy of Science Transactions 63 (3) 1264-272. 
Suiru, Purine W. 1965. A preliminary annotated list 
the lampreys and fishes of Illinois. Illinois Natu 
History Survey Biological Notes 54. 12 p. 
. 1968. An assessment of changes in the fish fal 
of two Illinois rivers and its pearing on their fut 
. 4 
Illinois State Academy of Science Transactions 61(- 
31-45. 
STARRETT, WILLIAM C., WILLIAM J. Harry, and Par 
Surru. 1960. Parasitic lampreys of the genus Ich 
omyzon in the rivers of Illinois. Copeia 1960 (4) 1337- 
