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LIBRARY OF THE
UNIVERSITY OF ILLINOIS
AT URBANA-CHAMPAIGN

no.6G@ - 99

SURVEY

ILLINOIS STREAMS:

A Classification Based on Their Fishes
and an Analysis of Factors Responsible

for Disappearance of Native Species
By Philip W. Smith

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ILLINOIS STREAMS: A Classification Based on
Their Fishes and an Analysis of Factors Responsible
for Disappearance of Native Species

ILLINOIS HAS MANY different drainage systems.
It is bounded on the west, south, and southeast by
great rivers and on the northeast by Lake Michigan.
Within its borders it has many creeks, rivers, ponds,
and artificial lakes, plus a few glacial lakes in the
northeastern corner of the state. Thus it is not sur-
prising that almost 200 species of fishes have been
recorded in the state. The great number of streams
and variety of stream habitats are primarily responsible
for the richness of the Illinois fauna.

As a group, fishes are tolerant and adaptable or-
ganisms that can survive considerable habitat abuse,
but the ecological tolerances of the many different
species vary tremendously. The presence of fish indi-
cates little about the condition of a stream, but a
knowledge of the assemblage of species and _ their
numerical relationships provides the ichthyologist with
an excellent biological picture of the water course
and its well being. When such information is available
over a long period of time, fishes can be one of the
most sensitive indicators of the quality of the aquatic
environment.

From time to time for more than a hundred years,
ichthyologists at the Illinois Natural History Survey
and other agencies have conducted censuses of Illinois
fishes so that, in a sense, changes in the aquatic envi-
ronment have been monitored all this time. A particu-
larly thorough collecting program spanned the period
from 1876 to 1905 and culminated in publication of
the classic “Fishes of Illinois” (Forbes & Richardson
1908). The collecting stations are shown in Fig. 1.
Another program, begun in 1950 and recently com-
pleted, was even more thorough, thanks to modern
transportation facilities. The collecting stations are
shown in Fig. 2. A wealth of information on changes
in fish populations and aquatic habitats in Illinois has
been assembled by comparing distributional patterns
and census data from the two surveys, and this in-
formation is available to interested agencies.

Analysis of these data has made it possible to as-
sign virtually all of the streams in the state ratings

_ of excellent, good, fair, or poor. The ratings are based
| on the species composition of the hundreds of collec-

tions available. It has also been possible to detect
long-term changes, and to identify factors that are

:
This paper is published by authority of the State of Illinois,
IRS Ch. 127, Par. 58.12. It is a contribution from the Section
| of Faunistic Surveys and Insect Identification of the Illinois
| Natural History Survey. Dr. Smith is a Taxonomist and Head

of the Section of Faunistic Surveys and Insect Identification.

Philip W. Smith

responsible for each stream’s deterioration and each
species’ change of status.

Owen F. Glissendorf, Technical Editor of the Sur-
vey, edited the manuscript. Lawrence M. Page aided
in the analysis of data and critically read several pre-
liminary drafts of the manuscript. He and R. Weldon
Larimore provided counsel in many areas. Douglas
W. Schemske compiled the counts of species known
from each drainage system by consulting species dis-
tribution maps. Since 1962, Alvin C. Lopinot and his
staff in the Division of Fisheries of the Illinois Depart-
ment of Conservation have deposited in the Survey
collection hundreds of fish collections made through-
out the state. I have made free use of information
assembled in the series “Surface Water Resources” for
Illinois counties issued by the Division of Fisheries
and recommend these publications to anyone inter-
ested in more specific detail about his own county.

CLASSIFICATION AND
DESCRIPTION OF STREAMS

The following annotated list of stream systems rates
each stream on the basis of fishes presently known
to occur in it and its potential for harboring others.
A rating of excellent signifies that the expected species
are still present in a numerical relationship to each
other that indicates little modification of the stream
from its original condition. Good, fair, and poor are
self-explanatory. Consideration has been given to the
varying adequacy of sampling different stream sys-
tems. Unusual species and habitats, if present, are
noted, and sources of problems in the stream, if they
can be identified, are indicated.

The order of treatment is roughly north to south.
Stream systems are numbered and can easily be lo-
cated on the accompanying map (Frontispiece). Tribu-
taries of the river cited are discussed only if their
condition differs from that of the main stream. Near-
by small streams that are not tributaries are some-
times included because of their proximity and simi-
larity. For example, Menominee, Smallpox, and
Sinsinawa creeks are not tributaries of the Galena
River, but they are close to the Galena River, and it
is convenient to treat the four streams as one unit.
The Mississippi, Ohio, Wabash, and Illinois rivers are
not included in the annotated list, but their species of
fishes are included in the counts for the stream systems
if records are available for sites near mouths of the
streams.

Fig. 1—Locations of collections of fishes made from
1876 to 1905.

The common names of fishes used in this article
are those recommended in American Fisheries So-
ciety Special Publication No. 6 (Bailey et al. 1970),
in which the scientific names can also be found.

1. Galena River system (including Menominee,
Sinsinawa, and Smallpox creeks).—Rating good.
Species present, 58. Unusual species: longnose dace.
Unusual habitats are the gravel-rubble riffles and
marginal aquatic vegetation. Barnyard pollution is
a minor problem.

2. Apple River system.—Rating good to excellent
(in upper reaches). Species present, 62. Unusual
species: Ozark minnow. Unusual habitats are gravel
riffles and clear pools. Some barnyard pollution is
present and siltation is a problem in lower reaches,
but in general Apple River and its tributaries are ex-
ceptionally clean streams.

3. Plum River system (including Johnson, Rush,

Fig. 2—Locations of collections of fishes made from
1950 to 1971.

and Otter creeks ).—Rating fair. Species present, 53.
Unusual species: brassy minnow. Unusual habitats
are gravel riffles. Barnyard pollution and siltation
are the principal problems.

4. Rock-Green River system (including Mere-
dosia Ditch)—Except where it borders or passes
through highly urbanized and industrialized areas,
the Rock River is rated good and, in some areas, ex-
cellent. Species present, 98. The Pecatonica and
Green rivers are only fair because of siltation and
agricultural pollution. Such tributaries as the Kish-
waukee, Leaf, and Kyte rivers and Elkhorn, Pine,
Grove, and Piscasaw creeks are good to excellent;
other tributaries are fair to good. Unusual species:
lake sturgeon, gravel chub, Ozark minnow, brook
stickleback, and brassy minnow. Unusual habitats are
the rocky and gravelly raceways in some of the rivers,
and the small brooks with aquatic vegetation. De-

spite the dams on the Rock River and the urbanization
along its banks, the system has not been affected as
severely as many other drainages in the state.

5. Edwards River system (including Copperas and
Pope creeks ).—Rating poor to fair. Species present,
52. Habitats are limited, and many of the streams
are sand choked and rather sterile. Problems are
dredging, agricultural pollution, siltation, and the
lack of habitat diversity.

6. Henderson Creek system (including Ellison
and Honey creeks ).—Rating poor to fair. Species
present, 57. Most of the streams contain excessive
amounts of silt in their headwaters and sand in lower
stretches. Problems are siltation, agricultural pollu-
tion, and lack of habitat diversity.

7. Bear Creek system (including several small,
direct tributaries of the Mississippi River).—Rating
poor to fair. Species present, 54. Sand, gravel, and
rocky riffles and pools are present, but species di-
versity is low. Problems are desiccation during drought
periods and rather severe agricultural pollution.

8. The Sny-Bay Creek system (including several
small, direct tributaries of the Mississippi River).—
Rating poor to fair. Species present, 76. Many habi-
tats are available, and Bay Creek appears to be an
outstanding stream with water of high quality. Prob-
lems are desiccation during drought periods and agri-
cultural pollution, but these factors cannot account
for the low species diversity in the system.

9. The Des Plaines River system (including Du-
Page River, Salt Creek, and other direct tributaries
and canals of the Illinois River).—Rating poor. Species
present, 63. Problems are domestic and industrial
pollution and extensive modification of streams and
habitats. It is remarkable that so many streams still
contain fish, although some support only goldfish,
goldfish-carp hybrids, and green sunfish. Prairie and
Jackson creeks have good species diversity, but Hick-
ory Creek is the outstanding stream in the system
and contains populations of such unusual species as
the northern hogsucker, rosyface shiner, and slender
madtom.

10. Fox River system (including glacial lakes of
Lake and McHenry counties and Aux Sable Creek).—
Rating good to excellent. Species present, 102. Un-
usual habitats are the clear well-vegetated natural
lakes, clear gravel-bottomed creeks, and spring-fed
streams. Unusual species: blackchin shiner, banded
killifish, brown bullhead, Iowa darter, banded darter,
and mottled sculpin. The Fox River proper has some
domestic and industrial pollution, but most of its
tributaries have a variety of habitats and rather high
species diversity. Many of the glacial lakes have
been ruined by pollution and introduction of sport
fishes; others, such as Channel, Grass, Loon, and
Cedar lakes, contain a rich variety of native species.
Some of the species in this system do not occur any-
where else in the state.

ll. Little Vermilion (of the north) system (in-
cluding several nearby direct tributaries of the Illi-
nois River )—Rating fair. Species present, 52. Un-
usual habitats include clear, gravelly streams. Un-
usual species: mottled sculpin. The species diversity
is rather low, despite the availability of relatively
unaltered habitats.

12. Big Bureau Creek (including the Illinois and
Mississippi Canal and Senachwine Creek).—Rating
good to excellent. Species present, 74. Unusual habi-
tats in the area are the fast, sandy and gravelly riffles
and clear pools. Some of the streams are sand choked,
and the canal is badly silted. Big Bureau Creek and
its larger tributaries are relatively unaltered, and
agricultural pollution has not had an appreciable
effect on the species diversity.

13. Kankakee-Iroquois River system (including
marginal sloughs and drainage ditches in marshes and
sand areas).—Rating excellent. Species present, 72.
Unusual habitats are swamps, marshes, clear well-
vegetated streams, gravel-rubble riffles, and sand-bot-
tomed pools. Unusual species: ironcolor shiner, weed
shiner, blacknose shiner, lake chubsucker, starhead
topminnow, northern longear sunfish, and least darter.
The Kankakee River and most of its tributaries have
excellent species diversity. The Iroquois River is
rather sluggish, brushy, and turbid, but some of its
tributaries, notably Beaver and Sugar creeks, contain
rich assemblages and unusual species.

14. Mazon Creek system (including nearby small,
direct tributaries of the Illinois River ).—Rating good.
Species present, 67. Unusual habitats include exten-
sive beds of marginal aquatic vegetation and gravelly
riffles and pools. Unusual species: black redhorse, big-
eye shiner, and banded darter. Mining and agricultural
practices in the area have not appreciably damaged the
streams in the system.

15. Vermilion (of the north) River system (in-
cluding Covel Creek and other nearby small, direct
tributaries of the Illinois River )—Rating fair. Species
present, 80. Unusual habitats are gravelly and sandy
rifles and pools, extensive areas of marginal aquatic
vegetation, and rocky riffles. Covel Creek has such
unusual species as the black redhorse and slender
madtom. The Vermilion River has a variety of habi-
tats and should have a richer fish fauna than it has.
It has some domestic and agricultural pollution along
its length, and its badly silted headwaters are peri-
odically dredged.

16. Kickapoo Creek (including Copperas Creek).
—Rating good. Species present, 76. Unusual habitats
are the clear, gravelly raceways and sand-gravel rifles.
Unusual species: blacknose dace, redbelly dace,
hornyhead chub.

17. Spoon River system (including nearby direct
tributaries of the Illinois River ).—Rating fair. Species
present, 87. In view of the size of the watershed
and number of habitats available, the species diversity

5

should be greater than our collections indicate. Prob-
lems are excessive siltation, agricultural pollution, and
desiccation of small streams during drought periods.

18. La Moine River system (including McKee,
Sugar, Crooked, and Bay creeks).—Rating fair.
Species present, 78. Problems are siltation, severe
agricultural pollution, and desiccation of small streams
during drought periods. A few small streams in the
area are spring fed and have clear, gravelly riffles.

19. Mackinaw River system (including nearby
small, direct tributaries of the Illinois River) —Rating
good to excellent. Species present, 100. Unusual habi-
tats are sandy and gravelly riffles and pools, and
extensive areas with marginal aquatic vegetation. Un-
usual species: rosyface shiner, silver redhorse, and
freckled madtom. Problems are siltation, dredging,
and agricultural pollution. Many habitats are pres-
ent, and species diversity in the Mackinaw River
proper is quite high.

20. Sangamon River system.—Rating variable.
Species present, 94. Unusual habitats are sand-bot-
tomed pools, submerged aquatic vegetation, gravelly
riffles, and some deep pools. Unusual species: high-
fin carpsucker, silver redhorse, ironcolor shiner,
spotted sunfish, and banded darter. Problems are
siltation; the Lake Decatur dam; industrial, domestic,
and agricultural pollution; and dredging. Because
of the size of the basin, many different habitats are
available and there is a high diversity of species.
Salt Creek and its tributaries are less altered than
the Sangamon River proper, although both branches
have lost some of the species they once had. The
headwaters of the Sangamon, Kickapoo Creek, and
some small tributaries near the mouth of the Sanga-
mon support particularly rich assemblages of fishes
and are rated good; other areas are rated fair.

21. Indian-Sandy-Apple-Macoupin-Otter creeks
(including other small, direct tributaries of the lower
Illinois and Mississippi rivers ).—Rating variable.
Species present, 87. Unusual habitats include some
cold springs and sand-bottomed pools. Unusual
species: hornyhead chub, bigeye shiner, redbelly dace,
and banded sculpin. Problems are siltation, desicca-
tion during droughts, and agricultural pollution. Otter
and Mill creeks have good species diversity; the other
streams in the area are rated poor.

22. Wood River-Cahokia Creek (including other
small tributaries of the Mississippi River in Madison,
St. Clair, and Monroe counties).—Rating poor. Species
present, 64. Problems are extensive industrial pollu-
tion, siltation, and desiccation of small streams during
drought periods. The streams in the area lack variety
in aquatic habitats and would not have great species
diversity even if they were not polluted and otherwise
altered.

23. Kaskaskia-Marys River system.—Rating vari-
able. Species present, 104. Because of the size of the
basin and large variety of habitats, an exceptionally

6

large number of species occurs in this system. Un-
usual habitats include swamp, sand-gravel riffles and
pools, and deep pools. Unusual species: blue sucker,
freckled madtom, slender madtom, bigeye shiner,
sauger, and river darter. The headwaters of the
Kaskaskia are periodically dredged, and the upper sec-
tion receives much agricultural pollution and some in-
dustrial pollution from a manufacturing plant near
Tuscola. The middle section of the river receives
mine wastes and oil-field pollution. The lower section
has been channelized for barge traffic. Many of the
tributaries are low-gradient, brushy sloughs that have
a limited number of habitats. Such tributaries as
Shoal Creek, Crooked Creek, and Silver Creek are
swampy with usually turbid water. Until recently
the least disturbed part of the basin was the Kaskaskia
River and its tributaries in Moultrie, Shelby, and
Fayette counties, but the recent creation of Lake
Shelbyville destroyed most of the habitats upstream
from Shelbyville. Although there is a long list of
species recorded from the Kaskaskia system, many
species will probably disappear soon. The Marys
River would have very poor species diversity were
it not for several large-river species that ascend the
Marys from the Mississippi River.

24. Big Muddy River system.—Rating good in
lower reaches, very poor upstream from Murphysboro.
Species present, 88. The marginal swamps of the
lower course are rich in species. Until the recent cre-
ation of Lake Kinkaid, Kinkaid Creek was the out-
standing tributary of the Big Muddy. Other tribu-
taries such as Beaucoup Creek, Little Muddy River,
and Crab Orchard Creek are low-gradient, brushy
streams with little habitat variety, and Crab Orchard
Lake has destroyed many of the smaller streams in
the system. Most of the basin suffers from siltation,
desiccation during drought periods, and oil-field and
other industrial pollution. The low quality water sup-
ports only the most ecologically tolerant and tenacious
species of fishes in the middle and upper parts of the
basin.

25. Clear Creek-Horseshoe Lake system.—Rating
excellent. Species present, 99. Unusual habitats in-
clude the nearly unique Pine Hills swamp, luxuriant
beds of aquatic vegetation, many cold springs, clear
gravelly tributaries, and a large-river habitat near the
mouth of Clear Creek. Horseshoe Lake is a typical
cypress-lined oxbow with good populations of swamp
species. Unusual species in the system: spring cave-
fish, spotted gar, starhead topminnow, banded pygmy
sunfish, bantam sunfish, flier, blacktail shiner, central
mudminnow, and river darter. Although much of
Clear Creek appears to be a lowland stream, it and
its clear, gravelly tributaries have an incredible list
of species, some of which do not occur anywhere else
in the state.

26. Cache River system—Rating good. Species
present, 81. Although the lower and middle stretches

of the Cache River consist of cypress swamp and mud-
bottomed sloughs, many of the headwater streams
are clear and gravelly, and some are spring fed.
Unusual species: flier, blackspotted topminnow,
cypress darter, spottail darter, and stripetail darter.
Problems are desiccation during drought periods and
siltation.

27. Massac-Bay-Lusk-Big Grand Pierre-Big Creek
system (including many lesser direct tributaries of the
Ohio River and some marginal lakes and swamps).—
Rating excellent to good. Species present, 79. The
outstanding stream in the system is Big Creek, closely
followed by Lusk Creek. Unusual habitats are clear,
rock-bottomed pools, gravelly riffles, and cold springs.
Unusual species: black redhorse, rock bass, small-
mouth bass, cypress darter, spottail darter, stripetail
darter, and banded sculpin. The smaller streams in
the area are rated fair, and those not fed by springs
are subject to desiccation during drought periods and
to some agricultural pollution. The lowland lakes
and swamps have good populations of lacustrine
species such as the pugnose minnow.

28. Saline River system.—Rating poor. Species
present, 57. Problems are stripmine wastes, siltation,
oil-field pollution, drainage of natural lakes and ponds,
desiccation during drought periods, and a paucity
of aquatic habitats. Some parts of the Saline River
are devoid of fish because of the discharges of acid
from coal mines, and its tributaries have rather low
species diversity. Several species have been extirpated.

29. Little Wabash River system.—Rating poor in
lower reaches but very good in upper part of the
system. Species present, 78. Problems are oil-field
pollution, siltation, and desiccation during drought
periods. Tributaries such as the Skillet Fork, Elm
River, and Fox River are low-gradient, brushy streams
with oil pollution and very low species diversity. The
Little Wabash River between Louisville and Neoga
has alternating pools and sand or sand-gravel riffles
and high species diversity. Unusual species: spotted
bass, bigeye shiner, greenside darter, and dusky darter.
Tributaries in the upper portion of the basin are
shallow, sandy streams with fair species variety; the
headwaters of the Little Wabash above Lake Mattoon
are badly silted.

30. Bonpas Creek system (including some small,
direct tributaries of the Wabash River ).—Rating fair.
Species present, 71. There is a limited number of
habitats available in this small watershed, and oil-field
pollution, drainage of natural lakes and ponds, and
siltation have taken their toll of native species. Un-
usual species in the system are the pugnose minnow
and spotted sucker; the nearby Wabash River has an
extremely rich variety of species.

31. Embarras River system.—Rating — variable.
Species present, 92. The lowermost section of the
Embarras has oil-field pollution and has been partly
rechanneled, and the headwaters above Lake Charles-

ton are badly silted. A major tributary, the North
Fork, has severe oil-field pollution and siltation. These
three areas must be rated fair to poor, but the major
part of the Embarras River proper and especially the
stretch from Charleston to Newton has an excellent
variety of habitats and extremely rich species diversity.
Unusual species: harlequin darter, dusky darter, east-
ern sand darter, spotted bass, mountain madtom, and
greenside darter. The harlequin darter does not occur
anywhere else in the state. The middle section of
the Embarras is one of the outstanding Illinois streams.

32. Direct tributaries of the Wabash River in
Crawford, Clark, and Edgar counties—Rating good.
Species present, 82. The outstanding streams in the
system are Mill Creek, Big Creek, and Brouilletts
Creek, all of which contain sandy and gravelly pools
and riffles and water of high quality. Unusual species:
blacknose dace, redbelly dace, greenside darter, and
bigeye shiner. Some oil-field pollution exists in the
watersheds, but the streams suffer most from desicca-
tion during drought periods.

33. Little Vermilion-Vermilion River system.—
Rating variable. Species present, 86. The Little Ver-
milion has been in part rechanneled and dredged
and is subject to desiccation during low-water periods.
The Vermilion is badly polluted by domestic sewage
several miles downstream from Danville but recovers
before it leaves the state. The North Fork is badly
silted above Lake Vermilion and somewhat polluted
below the lake. The West Branch is devoid of fish
most of the year because of domestic sewage from
Champaign-Urbana, and the East Branch receives
some pollution from Rantoul and Chanute Air Force
Base. The Salt Fork between Homer and Danville
consists of clear pools, wide sand and gravel bars,
and rubble-gravel riffles and has quite high species
diversity. The outstanding stream in the system, and
one of the finest in Illinois, is the Middle Fork, which
in addition to the habitats listed for the Salt Fork
has some boulder riffles and exposures of bedrock.
Unusual species: bluebreast darter, river redhorse,
dusky darter, eastern sand darter, mimic shiner, and
rosyface shiner. The bluebreast darter does not occur
anywhere else in the state.

The number of species in a stream system de-
pends on the number of relatively unmodified habitats
available. In general, a large drainage system will con-
tain a greater variety of habitats and more species
than a small one. For example, the Kaskaskia River
system is the largest in Illinois and has the greatest
variety of fishes (104 species). However, the re-
lationship is not absolute. Other stream systems with
high species diversity are the Fox (102 species),
Mackinaw (100 species), Clear Creek (99 species),
Rock-Green (98 species), Sangamon (94 species), and
Embarras (92 species). The Fox, Mackinaw, and
Embarras systems are moderate in size, and Clear
Creek has a rather small drainage basin.

7

Some of the systems with low species diversity are
the Edwards (52 species), Little Vermilion (of the
north) (52 species), Plum (53 species), Bear Creek
(54 species), and Saline (57 species). Most of these
streams have rather small watersheds.

LONG-TERM CHANGES
IN ILLINOIS FISH POPULATIONS

If freakish discoveries of aquarium escapees and
released pets are ignored, the list of species recorded
from Illinois waters stands at 193 (13 naturalized and
180 native species ).

Four of the 13 non-native species (brown trout,
goldfish, carp, and grass carp) are exotic species.
Six of them (rainbow trout, brook trout, coho salmon,
chinook salmon, American smelt, and white catfish)
are native to other parts of this continent and have
been deliberately stocked in Illinois waters. Three
of them (sea lamprey, alewife, and threadfin shad)
are native to other parts of this country and have
recently extended their ranges into Illinois.

Of the 180 native species, 8 (silverjaw minnow,
bigmouth shiner, red shiner, redfin shiner, fathead
minnow, creek chub, mosquitofish, and redear sun-
fish) have expanded their ranges in Illinois and in-
creased in abundance. The first three cited thrive in
small, shallow streams with sand bottoms and mod-
erate current and are quite resilient to dredging,
straightening, and other modifications of streams.
It has been shown that in Champaign County, streams
tend to be wider and shallower than formerly (Lari-
more & Smith 1963:320), thus increasing the amount
of preferred habitat for these mobile and aggressive
species. Similar changes have occurred over the entire
state.

The redfin shiner, fathead minnow, and creek
chub occupy quiet pools of small streams with silt
bottoms, and they are rather tolerant of turbid waters.
Siltation and other human alteration of watersheds
have increased the amount of favorable habitat for
these fishes. The mosquitofish and redear sunfish,
native to southern Illinois, have been widely trans-
planted in efforts to control mosquitoes and to provide
another species of panfish in many reservoirs. Both
are tolerant of some habitat abuse and have strong
dispersal powers.

For 104 of the native species little change was
revealed in distribution and abundance. This may
be attributed to less adequate sampling during the
first censusing as reported by Forbes & Richardson
(1908) or because the change in status of these
species could not be clearly demonstrated for various
reasons.

Eight native species have been extirpated in TIli-
nois and 60 other native species show clear-cut evi-
dence of range shrinkage and decimation. Some of
the latter group reveal rather minor reductions in

8

range size and abundance; others are so severely
decimated as to be endangered, and some of them
may have been extirpated in Illinois since our survey
was completed.

FACTORS RESPONSIBLE FOR
CHANGES IN FISH POPULATIONS

If the present ranges and former distributions of
the native fish species in Illinois are carefully ex-
amined, it is possible in most cases to identify the
factor chiefly responsible for the extirpation or decima-
tion of each species. A tally of the species affected
by each identified factor permits an objective assess-
ment of the environmental changes responsible and
brings each factor into perspective.

Silt

Excessive siltation ranks first and is implicated as
the principal cause for the extirpation of 2 native
species and the decimation of 14 others. Its effects
include loss of water clarity and subsequent disap-
pearance of aquatic vegetation, and the deposition
of silt over substrates that were once bedrock, rubble,
gravel, or sand. Feeding and spawning sites, as well
as the usual habitats for such fishes, have been reduced
over much of the state.

The crystal darter, described from a small tribu-
tary of the Mississippi River in Hancock County
(Jordan 1878:38), once occurred also in the Rock
River, Little Wabash River, and Mississippi River
in Jo Daviess County (Forbes & Richardson 1908:301),
but it has not been found in the state since 1900.
The gilt darter was collected in the Rock River as
early as 1877 (Forbes & Richardson 1908:289) and
found there in 1927 and 1932 (O'Donnell 1935:489),
but it has not been taken anywhere in the state since,
despite careful searches in recent years.

The bigeye shiner, bigeye chub (Fig. 3), and
pugnose minnow (Fig. 4), all of which require clear
water, have been decimated primarily because of the
disappearance of aquatic vegetation. The mooneye,
highfin carpsucker (Fig. 5), rock bass, longear sunfish,
and walleye have been adversely affected by increas-
ing water turbidity. The gravel chub (Fig. 6), Ozark
minnow, weed shiner (Fig. 7), western sand darter,
banded darter (Fig. 8), and slenderhead darter have
reduced ranges because they have lost extensive
gravel- and sand-substrate habitats to silt.

Excessive siltation has adversely affected fishes
over a long period of time and has drastically altered
stream habitats over the entire state with the possible
exception of high-gradient streams in extreme north-
western Illinois.

Drainage

Drainage of natural lakes, sloughs marginal to
large rivers, swamps, and prairie marshes ranks sec-
ond in importance and is responsible for the shrink-

4. /
NOTROPIS
EMILIAE

3.
HYBOPSIS
AMBLOPS

—_

zie

ee
Re

1 i
6. NOTROPIS
HYBOPSIS TEXANUS

X-PUNCTATA

| I
te}

ACRE EN
yA

ay

as 4
CARPIODES =~
VELIFER

8. Z
ETHEOSTOMA
ZONALE

Fig. 3-8—Some species of fishes decimated because silt has destroyed many of their habitats. The bigeye chub,
last collected in Illinois in 1961, may already be extirpated. Circles, before 1905; dots, after 1950.

age in range of 13 native species. The populations of
pugnose shiner, blackchin shiner, blacknose shiner
(Fig. 9), and banded killifish (Fig. 10) have been
reduced to a few glacial lakes in extreme northeastern
Illinois as a result of the widespread drainage of
natural lakes and marshes in the northern half of the
state. The ranges of the bowfin, central mudminnow
(Fig. 11), lake chubsucker, brown bullhead (Fig. 12),
starhead topminnow (Fig. 13), pygmy sunfish, bantam

sunfish, spotted sunfish, and Iowa darter (Fig. 14)
have shrunk as a result of the drainage of the floodplain
lakes and sloughs marginal to the large rivers.
Strictly lacustrine species such as the pugnose
shiner, blackchin shiner, and banded Killifish are
especially affected, for when the lake is drained the
populations of these fishes are eliminated and there
is no opportunity for recruitment into newly created
impoundments. Semilacustrine species such as the

9

Sty

=

10.
FUNDULUS
DIAPHANUS

ee

TCTALURUS : FUADULUS 7
NEBULOSUS NOTTI

ait
re
LS

iy
ae:

a
fe
Me
ip

Fig. 9-14—Some species of fishes decimated because drainage of natural lakes, sloughs, and marshes has destroyed

many of their habitats. Circles, before 1905; dots, after 195

bowfin, mudminnow, and others, on the other hand,
may have nearby populations in stream oxbows or
pools that can disperse into new bodies of water.
However, new artificial lakes are usually populated
by stocked species and minnow-bucket releases.

Drainage has affected fishes for many years and
has produced the most dramatic effects by the elimina-
tion of bottomland lakes and sloughs marginal to
all of the large rivers and the prairie swales through-
out the northern half of Illinois.

10

0.

Desiccation During Drought

Desiccation of stream systems during drought
periods ranks third in importance and is responsible
for the range shrinkage of 12 species. In recent
decades the water table has fluctuated more widely
than it did before 1930. During severe late summer
and fall drought, streams that were once permanently
flowing now dry up, seeps and springs cease to flow,
and some relatively large rivers temporarily become
medium-sized or small streams.

a

The effects of desiccation have been particularly
devastating on headwater and creek species such as
the silvery minnow (Fig. 15), hornyhead chub, striped
shiner, redbelly dace, blacknose dace, longnose dace,
creek chubsucker (Fig. 16), bluntnose darter (Fig.
17), and slough darter. The effects of reduction in
size of streams on large-river species are most dra-
matically seen in range shrinkage of such typical
large-river species as the emerald shiner (Fig. 18),
bullhead minnow (Fig. 19), and mud darter (Fig.

Seas
=< we UR t Siwy,
ai
a

©) &) eal a
ant bo

3 16. /
HYBOGHATHUS Gace

NUCHALIS

19. /
PIMEPHALES
VIGILAX

1
NOTROPIS
ATHERINOIDES

) fe Pl
aks
Ke |

20). When large-river habitat is no longer avail-
able, these fishes move downstream to their proper
habitat or perish. Annual droughts require that tribu-
taries be reoccupied each spring when the streams
are flowing again and are of sufficient size to provide
the proper habitat.

Stream desiccation is a relatively new factor that
has had its most devastating effects since 1930. Prior
to that year droughts had less effect because the
water table was less variable. Desiccation has been

Cpt

sre

1. ie
ETHEOSTOMA Ds
CHLOROSOMUM tec

20.
ETHEOSTOMA
ASPRIGENE

Fig. 15-20.—Some species of fishes decimated because desiccation during drought periods has eliminated many of their

habitats. Circles, before 1905; dots, after 1950.

11

most damaging in southern, western, and central IIli-
nois. During severe droughts, swamps, springs, creeks,
and even small rivers have dried up.

Species Interaction

Species interaction following modification of a
stream or watershed ranks fourth and is responsible
for the extirpation in Illinois of the Ohio lamprey and
the rosefin shiner and the decimation of seven other
species. Prior to 1917 the Ohio lamprey occurred in
the Wabash watershed, but the allied and allopatric
chestnut lamprey has since supplanted the Ohio lam-
prey in all of eastern Illinois and western Indiana (Star-
rett, Harth, & Smith 1960). The rosefin shiner occurred
in extreme southeastern Illinois in the last century but
has been supplanted in Illinois and adjacent Kentucky
by the more ecologically tolerant and allopatric redfin
shiner.

In addition to competition between members of a
pair of closely related fishes, there have been inter-
actions unrelated species that resulted in the decima-
tion of several native species. The explosive appear-
ance of the sea lamprey in Lake Michigan in the
1940’s was followed by a dramatic decline in popu-
lations of the cisco, lake whitefish, round whitefish,
lake trout, and burbot. When the ecological balance
was upset by sea lamprey predation, the alewife ap-
peared and mushroomed in numbers to become a seri-
ous pest in Lake Michigan.

The aggressive and ecologically tolerant red shiner
has gradually moved eastward in Illinois (Larimore
& Smith 1963) and has displaced the related spotfin
shiner (Fig. 21), and steelcolor shiner (Fig. 22) in
most parts of central Illinois (Page & Smith 1970).
Habitat modification evidently resulted in a break-
down of the reproductive isolating mechanisms in

21. 22.
NOTROPIS NOTROPIS
SPILOPTERUS WHIPPLE!

12

this group of species and permitted the red shiner to
hybridize with and eventually replace the other two
species.

Such species interactions have been in progress
for a long time and throughout the state. The effects
on certain native fish by the introduced carp and
goldfish are so well known that no comment is re-
quired. More recent stockings of the white amur,
redear sunfish, mosquitofish, white catfish, and salmon
species outside their natural ranges may pose equally
serious threats to native fish populations in the future.

Pollution

Pollution other than silt includes industrial, domes-
tic, and agricultural pollutants and ranks fifth. It can be
implicated as the cause for the extirpation of two and
decimation of five fishes. The greater redhorse oc-
curred in Salt Creek in northeastern Illinois but dis-
appeared sometime after 1901 when the stream be-
came polluted. The cypress minnow occurred in the
Little Muddy River as late as 1940 and was eliminated
by pollution, presumably from nearby oil fields.

The ranges of the silver chub, river shiner, brindled
madtom (Fig. 23), bluebreast darter, and blackside
darter (Fig. 24) are less extensive than formerly
because of localized pollution in several stream sys-
tems in eastern and southern Illinois.

Virtually all of the streams and lakes in Illinois
have been affected to some degree by pollution.
Among the most dramatic illustrations are streams
and lakes in the greater Chicago area because of
industrial and domestic pollution, the Big Muddy and
lower Little Wabash systems because of oil-field
pollutants, the Illinois River because of domestic
sewage from Chicago and other cities, most of the
Saline system because of coal mine wastes, small

Fig. 21-22.—Two species of fishes deci-
mated because they were unable to com-
pete with the related red shiner after
their original habitats had been altered.
Circles, before 1905; dots, after 1950.

GPa

B. he m4.
NOTURUS 7 R (uO PERCINA
MIURUS = MACULATA

streams in western Illinois because of runoff from hog
farms, and the West Branch of the Salt Fork because
of sewage effluents from Champaign-Urbana.

Fish kills have occurred repeatedly when toxicants
such as anhydrous ammonia and cyanide have been
accidentally or deliberately dumped into streams.
In most cases the streams are repopulated in 2 or 3
years, but endemic and relict species cannot return
once the population has been eliminated.

The revelation that water pollution ranks fifth
among the principal causes for extirpation and decima-
tion of native fishes is rather surprising. However,
many fishes are remarkably resistant to some degree
of pollution as long as the physical habitat remains
intact. Also, in many parts of Illinois, pollution has
become critically severe only in the last few years,
whereas other factors have been operative for a
century or more.

Dams and impoundments

The construction of dams to create mainstream
impoundments ranks sixth and is responsible for the
decimation of four species of riffle-inhabiting fishes.
The flowing stream consists of alternating riffles and
pools. Riffles may flow over bedrock, boulders, rubble,
gravel, or sand, and each bottom type comprises a dis-
tinctive habitat. Pools also may have different habitats,
depending on the type of substrate and current. When
a stream is impounded, riffles are eliminated and the
bottom of the reservoir quickly becomes silt, resulting
in only one habitat. The richness of the fish fauna
is directly related to the number of different habitats
available. Dams also block natural migration and dis-
persal of fishes.

The greenside darter (Fig. 25), eastern sand darter
(Fig. 26), fantail darter, and dusky darter have been

Fig. 23-24—-Two species of fishes deci-
mated because pollution has lowered the
water quality of streams that they in-
habited. Circles, before 1905; dots, after
1950.

decimated in the North Fork (Vermilion drainage)
and Embarras River by mainstream impoundments
(Smith 1968). The bullhead minnow is now re-
stricted to that part of the Embarras River below the
Charleston dam but once occurred farther upstream.

The effects of dams on the fishes of the Mississippi,
Illinois, Kaskaskia, and Rock rivers are more difficult
to document, but the dams are insurmountable to
migratory fishes except when the streams are in flood
condition, and many miles of stream that formerly
contained several distinctive habitats now have only
one.

The several proposed reservoirs in Illinois threaten
many native species because they are planned for
some of the most valuable waterways left, and many
of the unique aquatic habitats in the state will be
lost if the streams are dammed.

Temperature

The cutting of marginal trees and other vegetation
that afford shade, coupled with a reduced flow of
cold springs and low water levels during summer
droughts, result in higher water temperatures now
than formerly. No data on past stream temperatures
are available, but temperature offers the most likely
explanation for the disappearance of the northern
pike in streams of western Union County, where it
occurred prior to 1900 (Forbes & Richardson 1908,
atlas of maps).

Outlier populations of such species as the horny-
head chub, blacknose dace, longnose dace, redbelly
dace, and hogsucker in Union County have also been
eliminated, probably because they cannot survive the
summer stream temperatures. However, in other areas
of the state their decimation is more likely the result
of stream desiccation and siltation.

13

26.
AMMOCRYPTA
PELLUCIDA

STOMA
BLENNIOIDES

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 Illinois fishes.

Number of Number of

species species
extirpated decimated
Silt 2 14
Drainage 0 is
Desiccation during drought 0 12
Species interaction 2 7
Pollution 2 5
Dams and impoundments 0 4
Temperature 0 1
Unknown causes 2 4

14

eee

Fig. 25-26.—Two species of fishes deci-
mated because impoundments have de-
stroyed many of their habitats. Circles,
before 1905; dots, after 1950.

LITERATURE CITED

BAILEY, REEVE M., Chairman. 1970. A list of common and
scientific names of fishes from the United States and
Canada. 3rd ed. American Fisheries Society Special
Publication 6. 150 p.

Forbes, STEPHEN ALFRED, and Ropert HArL RICHARDSON.
[1908]. The fishes of Illinois. Illinois State Laboratory
of Natural History [Urbana]. exxxi + 357 p. + separate
atlas of 103 maps.

JORDAN, Davin S. 1878. A catalogue of the fishes of Illinois.
Illinois State Laboratory of Natural History Bulletin
1(2) :37-70.

LARIMORE, R. WELDON, and PuHiLie W. SmirH. 1963. The
fishes of Champaign County, Illinois, as affected by 60
years of stream changes. Illinois Natural History Sur-
vey Bulletin 28(2) :299-382.

O’DonneELL, D. JoHN. 1935. Annotated list of the fishes
of Illinois. Illinois Natural History Survey Bulletin
20(5) 473-500.

Pace, LAWRENCE M., and RicHArp L, SmirH. 1970. Recent
range adjustments and hybridization of Notropis lutren-
sis and Notropis spilopterus in Illinois. Illinois State
Academy of Science Transactions 63 (3) :264-272.

SMirH, PHinie W. 1965. A preliminary annotated list of
the lampreys and fishes of Illinois. Illinois Natural
History Survey Biological Notes 54. 12 p.

. 1968. An assessment of changes in the fish fauna
of two Illinois rivers and its bearing on their future.
Illinois State Academy of Science Transactions 61(1):-
31-45.

SrarrertT, WILLIAM C., WILLIAM J. HARTH, and PHILIP W.
SmirH. 1960. Parasitic lampreys of the genus Jchthy-
omyzon in the rivers of Illinois. Copeia 1960 (4) :337-846.

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