Bulletin


STATE OF ILLINOIS

DEPARTMENT OF REGISTRATION AND EDUCATION

DIVISION OF THE

NATURAL HISTORY SURVEY
STEPHEN A. FORBES. Chief

Vol. XV. BULLETIN Article VII.

Some Observations on the Oxygen Require-

ments of Fishes in the lUinois River

BY

DAVID H. THOMPSON

PRINTED BY AUTHORITY OF THE STATE OF ILLINOIS

URBANA. ILLINOIS

October. 1925



ERRATA
Page 57, statistical headings: for Year 1920 read Year I'JIO; for Year W09 read

Year HUG; in the ratio heading, for 1909 read 1920, and for 1920 read 1910.

The entries in the Year columns should change places.

Page 85, line 13 from bottom, for 87 read 86.

Page 88, line 20, delete red.

Page 115, line 6, over the column of figures read Acres.

Page 136, line 5, for /J.T read 131.

Page 145, First table, 4th column, for S5.9~ read 33.40; last column, for .052

read .0418.

Second table, second column, for .2158 read .2004; 5th column, for

.1131 read .0977; last column, for .0926 read .0772.

Last table, second column, for .714 read .663 and for total read $4,710;

5th column, for .374 read .323 and for total read $2,201; the last column,

for .307 read .256 and for total read $1,700.

Page 146: First table, second column, for 8.02 read 7.45 and for total read

52.92; third column, for 3.45 read 2.88 and for total read 19.10; 4th column

for 19.28 read 17.90 and for total read 127.18; last column, for 8.29 read

6.92 and for total read 46.35.

Second table, for 43.02 read 38.66.

Last table, for 8.0 read 6.7.

Page 382. line 10 from bottom, for Plat ytlieinis read Plathcmis.

Page 385, in list, the specific names of No.'s 33, 35, and 40 should end in ns

instead of a.

Pages 445 (line 4), 448 (line 4), 449 (line 23), 454 (line 8 from bottom), read

Belostomklac for Belostomatidae.

Page 457, line 21, for cornutus read cornuta.



STATE OP ILLINOIS

DEPARTMENT OF REGISTRATION AND EDUCATION

A. M. Shei.tox. Director

BOARD OF

NATURAL RESOURCES AND CONSERVATION

A. M. Shelton. Chairman

Wlliam Tkelease, Biology John W. Alvord. Engineering

John M. Coulter, Forestry Kexdric C. Babcock. Representing the

Edson S. Bastin, Geology President of the I'nivrrsity of IIU-

WiLi-iAj[ A. NoYES, Chemistry nois

THE NATURAL HISTORY SURVEY DIVISION

Stephen A. Poures. Chief

•-'S^^^S^^

Scii.NKi'f & Barnes, Printers
Springfield. III.

1925



Article VII.

—

Some Obscnrntions on the Oxygen Requiretnents of

Fishes in the Illinois River. By David H. Thompson.

Introduction

The amount of oxygen dissolved in the water is one of the most im-

portant factors hmiting the fish life of the Illinois River. Every year

low dissolved oxygen concentrations over a large portion of the river

profoundly affect the food, distribution, and even the existence of the

fishes. In the conservation of the Illinois River fishery it becomes neces-

sary to evaluate the oxj'gen requirements of the more common fishes.

The Illinois Natural History Survey and the State Water Survey have

for many years conducted a biological and chemical survey of the Illi-

nois River. As a result, the general oxygen conditions are rather com-
pletely known for the various parts of the river during the different sea-

sons of the year, and the distribution of fishes is well enough understood

to show the general relation to the range of oxygen concentrations. The
present paper is the result of an attempt to determine more precisely the

minimal oxygen requirements of the common fishes and some of the

effects of low dissolved oxygen concentrations, especially in winter.

Dr. R. E. Greenfield and Mr. A. L. Sotier, of the State Water Sur-

vey, made a series of dissolved oxygen determinations on the river dur-

ing the latter part of January, 1925. They reported that the fishes were

crowding into the "spring holes" in Peoria Lake, evidently on account of

unsuitable conditions in parts of the lake which were frozen over. The
writer, accompanied part of the time by Mr. Sotier, spent the latter part

of January and all of February gathering data on the fish life of the river

and making dissolved oxygen determinations in places where fishes were

being taken, where fishes were dying, and where fishes usually had been

taken but were absent at the time on account of special conditions of the

water. Much credit is due a number of fishermen for collateral infor-

mation and for their co-operation in the field work.

Some valuable determinations of dissolved oxygen in the channel

were made by the State Water Survey on January 23 and 24 and on Feb-

bruary (i and 7, 1925, which are published here for the first time.

The General Relation of Ice and Dissolved Oxygen

It is a common observation that fish often die in the winter under the

ice. This has been noticed most often where the ice has completely

covered the water for a considerable period. It is also commonly said by



424

fishermen, in certain places, that when a hole is cut in the ice the fish

will come to the place "to get air" and are very easily taken. It seems
quite clear that the reason fish die under ice or come to holes in the ice is

because there is a deficiency of dissolved oxygen in the water.

A layer of ice over a body of water very effectually prevents the

interchange of gases between the water and the air. The ice itself does
not decrease the amount of oxygen, but it stops the aeration of the water.

The decrease in amount of dissolved oxygen is brought about by the oxi-

dation of organic matter in the water. This organic matter does not
oxidize directly, but it forms the food of the bacteria and of larger plank-

ton—the immense numbers of minute plants and animals which utilize

the oxygen in their life processes. As a result, the amount of dissolved

oxygen that is removed from the water depends on the amount of organic

matter present and on the rate at which this is consumed by aquatic organ-

isms.

The life processes of these plants and animals which consume the

oxygen go on very slowly in water that is cold enough to be covered with

ice. It would seem that for this reason those lakes and very sluggish

streams which are frozen over early and thaw out late would sutler

most from the lack of oxygen. However, due to their sluggishness the

solid organic matter settles to the bottom and can not quickly reduce the

dissolved oxygen content of the whole body of water. In the deeper

lakes fish do not die under the ice, probably because of the relative scanti-

ness of organic matter and the greater amount of dissolved oxygen in the

deeper water. In most streams large amounts of organic matter are

constantly being added by drainage from the land and by wastes from
cities. The stirring action of the current is usually sufficient to keep

much of the solid organic matter in suspension and thus it exposes all

parts of the stream to loss of oxygen. Some streams are so swift that

they do not freeze over completely, and enough open water i.> left to keep

the dissolved oxygen content of the water high enough for the life of

fishes.

Recent Observations on the Relation of Ice and

Dissolved Oxygen in the Illinois River

The Illinois River is not often covered with ice long enough for the

oxygen dissolved in the water to be reduced to a point where the fish

show signs of distress. The river froze over in December, 1924, and did

not thaw out until the first week in February, 1925. It was completely

covered with ice except for small patches of open water where the cur-

rent was swiftest, notably in Peoria Narrows and below all bridges.

Fishermen say that this is the first lime the river has been frozen over

for any considerable time since the winter of 1917-1918. Kofoid* states

that during the winter of 1894-95 the river froze over the latter part of

December and the ice did not go out until the last of February.. Thb

• EuL in. state Lab. Nat. Hist., 6:176. 1901.



425

ice was present during a prolonged period of low water, and it was ac-
companied by the almost complete disappearance of the plankton organ-
isms and by the death of large numbers of fish. Although this occurred
before the Chicago Drainage Canal was opened, it must be remembered
that the Illinois River was even then a heavily polluted stream. At that

time the volume of water carried was much smaller than at present and
the rate of flow was slower. It seems probable that the river because
of its slower current was more likely to freeze over then than now, but
that this tendency was partially counteracted by greater changes in level

which tended to break up the ice and keep the channel open.

During January and February, 1925, dissolved oxygen determina-
tions were made in the Illinois River and related waters between La Salle

and Meredosia. Table I shows the results of these determinations to-

gether with notes on ice conditions and temperature of the water. Since
the river froze over before Christmas, it seems probable that when the

field work was begun, January 2;5, dissolved oxygen concentration had
reached its lowest point. Sami^les taken on January 23 and 21 showed
about 1.7 parts per million of dissolved oxygen at Peoria Narrows, Pekin,
and Havana, but those from Henry and La Salle showed about 6 parts per
million. This is probably not because of better aeration up-stream but
becau.se the initial charge of oxygen dissolved in the water that diluted

the sewage had, on account of the low temperature, not yet been consumed.
It is quite probable that at this time the very low oxygen prevailed from
Peoria Narrows to the mouth of the river at Grafton. On I'ebruarv 2.

oxygen concentrations as low as 0.4 part per million were found in Mud
Lake, which is partly fed by river water. Records of bullheads dying
in the traps and seines in Treadway Lake and Coleman Lake indicate

tbat low dissolved oxygen concentrations prevailed also in those back-
waters that are fed by the river. A sample taken in the middle of Quiver
Lake showed 2.3 parts per million of dissolved oxygen. This compara-
tively high figure is due to the highly oxygenated water coming out of

Quiver Creek. On February 4 samples taken in Treadway Lake and
Coleman Lake showed over 5 parts per million of dissolved oxygen. This
high figure is brought about by the dilution of these lakes with Sanga-
mon River water. By February 5, when the river channel was partly

o])en, sam])les at Beardstown showed 3.3 and 3.7 parts per million of dis-

solved oxygen in mid-channel with 4.6 and 4.1 near the east bank, due

to the better water coming out of Sangamon River. On February 6 and
7 there was much open water, but the water temperature w-as still between
0° and 4° C. Samples taken at Henry and Chillicothe showed about

5 parts per million of dissolved oxygen, which is somewhat lower than

the up-stream samples taken two weeks previously ; but the samples taken

at Peoria Narrows and Pekin gave about 3 parts per million, almost twice

the amount found on the earlier trip. The thawing continued until the

channel was free of ice by February S. On February 10 at Browning
the channel showed 5.8 parts per million of dissolved oxygen. The next

day at Beardstown it was 6.6.



426

>



427

Dissolved oxygen

parts

per



428

=5 ^^'^
2 K ^- B
H p.

00 t-_ 00 tP
LA irf LA ec^

CO CS T-( CS M
(^ Lri -rr M C--

<r ea C-; ci
t-J CO LO 00

C5 ^ Ol r^ rH t- o CC Ol o
t~t-000SOO05O000»

o o — •- o
E-

a ESS
o o o o.^ *J *J .^
*J -*J -*-» ^J ft
o o o c o
mca cQcQ H

s a a a ® a a ® »
O O V u ^
.*_» J *J *J ^ 9 O

oooo — ooo—"--oooo

LA LA O
T-I tH CO I I I I Mill I I I I

LA -^ O LA

cc e<i -^ LA

o
"- a s

o



429

A sample taken February 17 at Peoria Narrows with some new
shore ice present showed 7.6 parts per miUion of dissolved oxygen, and
a sample on February 18 showed 7.2 at the same place, with no change
in temperature. On February 19 at Water-works Point, where there

was still some shore ice. samples showed 8.9 parts per million of dis-

solved oxygen. For the remainder of February the dissolved oxygen
figures ranged from 8 to 10 parts per million in the vicinity of Beards-
town and Meredosia, with no ice and with the water temperature abotit

4° C.

From late autumn until late spring the water of the Illinois River

is cold enough to slow down the oxygen consumption of the organisms
that utilize the sewage and other organic matter in the river to a point

where the rate of aeration balances or exceeds the rate of oxygen con-

sumption. Under these conditions the amount of oxygen present is suffi-

cient for the ordinary river animals. If, however, aeration is stopped
by the freezing over of the river the dissolved oxygen is gradually ex-

hausted until it becomes so low in Upper Peoria Lake that fish show
signs of distress. When this condition is established, it does not change
until the ice goes out or until it is diluted with a large amount of water
highly charged with oxygen. When the ice goes out of a small fraction

of the channel there is a marked increase in the amount of oxygen dis-

solved in the water, and in about a week the normal cold water concen-

tration of dissolved oxygen is established.

The Effect of Low Dissolved Oxygen
Concentrations on the Fishes of the Illinois River

Fishes, like all other living things, require a more or less constant

supply of oxygen to maintain the activities of life, but the minimal

amount may vary greatly for the different forms of life. A striking

example of this is the problem in hand. The minute organisms which

feed on sewage and other organic matter can live and consume oxygen
in concentration too small to support the life of fishes. Some of them,

indeed, can live in a total absence of dissolved oxj'gen, since they are

able to derive oxygen from complex organic compounds.
A fact of fundamental importance to the existence of fishes is their

ability to avoid oxygen concentrations that would be fatal to them. When
low dissolved oxygen concentration obtains in a body of water, such as

the Illinois River, the fishes retreat into backwater lakes, spring holes,

mouths of tributaries, and other places where stagnation has not de-

veloped.

A case of this kind recently occurred near the town of S[)ring Bay
on the east shore of upper Peoria Lake, where there is a lagoon fed by
springs. At rather low stages of the river this lagoon, which has an

area of about two acres, is filled with clear, well-aerated water, warm
enough to j)revent freezing. Some time after the river was completely

frozen over in January, 1925, the fishes began to crowd into this spring



430

hole, and several carloads of carp and buffalo were taken here during

the last two weeks of January. A rise in the stage of the river largely

diluted this better water with the oxygen-deficient river water, and large

numbers of minnows, large-mouth black bass fingerlings, crappies, sun-

fishes, etcetera, died ; and the carp became much distressed and swam
at the surface with their heads out of the water. Part of the ice then

went out of the channel, the dissolved oxygen in the river water increased,

and the fishes no longer were attracted to this place. The unusually large

numbers of gulls that frequented the river at that time may indicate an

unusually large number of dead fishes ; but, with the above exception,

no dead fishes were seen by the writer except where they had been con-

fined in live-boxes, traps, and nets, and could not escape from the oxygen-
deficient water.

Those animals which are more sedentary in their habits and can not

so readily avoid oxygen-deficient water suffer more severely than the

fishes. After the recent prolonged period of ice, large numbers of dead

snails were washed up on the east shore of lower Peoria Lake. Fisher-

men in the vicinity of Meredosia and Beardstown have in recent years

remarked the growing scarcity of air-breathing animals that hibernate

on the bottom of the river, such as bull-frogs, snapping turtles, and soft-

shelled turtles. Some of the turtles, however, such as the painted turtle,

the ridge-back turtle, and the terrapin, do not bury themselves in the mud
and hibernate, but remain active, as shown by the fact that they are caught
in hoop-nets and traps throughout the winter. These latter species of

turtles are much more plentiful in the lower Illinois River than the

hibernating species. In cold water, frogs and turtles utilize the oxygen
in the water and can dispense with the use of their lungs. If they re-

main active they select the better water the same as the fish; but if they

bury themselves in the mud and become dormant, it may be that they

die there from deficiency of oxygen during times of stagnation.

In the attempt to determine what dissolved oxygen concentrations

the different fishes avoid and what concentrations are fatal to them, dis-

solved oxygen determinations were made where fish were being taken,

where they customarily had been taken but were absent at the time, and
where fish were dying. The procedure followed was to accompany a

fisherman who was raising hoop-nets and take dissolved o.xygen samples
at the nets. This was done at nets which had been fishing one, two, or

at most three days, and, when convenient, both when the nets were set

and when they were raised. The samples were usually taken near the

bottom because that is where the fish spend most of their time. One
advantage of hoop-nets is that they can be used in all kinds of situations

where the hauling of seines is often impossible. For the purpose of

ascertaining the relations of fish life to dissolved oxygen, hoo])-nets

have the further advantage, that they fish a very restricted area. The
amount of fish taken by them depends on conditions which cause the fish

to move about, such as high winds, changes in the stage of water, changes
in the quality of the water, and changes in temperature. What may be



431

considered a disadvantage of hoop-nets is their selcctiveness. Sluggish
fish are not caught as often as active fish. Carp avoid small-mesh
nets and traps, but they are readily taken in large-mesh nets. Chan-
nel cat and bullheads seem to go most readily into small-mesh nets

and basket traps, probably because, being largely nocturnal and hifl-

ing during the day, they go into the nets for concealment.
Table II gives the winter data showing the relation of fishes to

different conditions of ice and dissolved oxygen. It seems quite cer-

tain that dissolved oxygen concentrations between zero and two
parts per million will kill all kinds of fishes. Carp and buf?alo have
been found living in water showing as low as 3.5 parts per million.

As a rule, a variety of fishes were found only when they were four

or more parts per million, and the greatest variety of fishes was taken
when there were nine parts per million. This catch was made on
February 2G-27 in Vette Swale when at least twenty-two and ]ier-

haps as many as twenty-six species of the larger fishes were taken
in nine 2y>-mch mesh four-foot hoop-nets.

It was noticed a number of times that carp and buffalo taken
from oxygen-deficient water were very light in color and sluggish
in their movements, while the same kinds of fishes taken from well-

aerated water were quite darkly pigmented and very active when
disturbed.

Mention was made by fishermen, from time to time, at several
points on the Illinois River, of the inferior value of certain fish be-
cause they were "gassy"—their expression for a taste and smell of

the flesh of the fish, like the smell of coal gas. Others have described
it as like the taste of kerosene or of tar ; but to the writer it seems
more than anything else like the smell of the putrifying mud on the
bottom of the river, which is very like that of coal gas. This taste is

often so pronounced as to make the fish very disagreeable as food.

"Gassy" fish are definitely associated with periods of prolonged ice

on the river, mortality in nets and traps, and other indications of a

.scanty supply of dissolved oxygen. The species which most com-
monly have this taste are carp, buffalo, channel cat, and bullheads, and
these are the species which are most often found living in water with
a low oxygen concentration. If these fishes are kept in well-aerated

M'ater for a few days, they lose this "gassy" taste.

During the winter, except when the river is frozen over, fishes do
not suffer directly from lack of dissolved oxygen. From November
to May, in open water, the rate of aeration exceeds the rate of oxygen
consumption, so that there is usually a sufficiency of dissolved oxygen.

In midsummer, down as far as Peoria and .sometimes below, except
during high water, lack of dissolved oxygen excludes fishes from large

feeding grounds and destroys large amounts of fish food. For example,
Mr. Richardson observed a heavy mortality of snails in Peoria Lake in

August, 1917. As increase in temiterature accelerates the life processes
of fishes, lack of dissolved oxygen can not be endured in warm water as

long as in cold.



432

y. T-K

f Eh

o a

to -C A
lU S tS« t,
• o
p. M

o CO a^ "' -

ja . a

S m w
cj

"
" ^ a

0) QJ O ^M O J-
o Jf

oi :=:

a! .2

•a ^u

3 rt

c



433



434



435

Summary op Table II

Col-

umn



436

Bureau of Fisheries. The factors entering into the increase of the fish

yield were principally

:

(1) The introduction of the German carp.

(2) The increase in fishing operations.

(3) The increase in the area of the river due to the addition of

water from Lake Michig^an.

(4) The increase in the food supply resulting from the sewage.

T.UJI.K



437

taken. Here the factors making for increased yield have been offset

largely by reclamation of the bottomlands. The greatest change took

place in the Peoria-Browning section, where there was a marked increase

in fish yield up to 190S and an equally marked decrease after 1908. Here
the reclamation of bottomlands, notably the Thompson's Lake district,

took place several years later than in the lower section of the river. In

the upper section (La Salle-Chillicothe), although considerably less land

has been reclaimed, and the higher stage of the river has increased the

area of water, the fish yield shown by the 1921 and 1922 figures is scarce-

ly half its former value. This decrease has been brought about entirely

by the conditions produced by an excess of sewage.. The most important

effect of an excess of sewage is the reduction of dissolved oxygen to a

point where fish life is excluded from immense areas of water.