LAKE MANAGEMENT REPORTS 
1. HorsESHOE LAKE NEAR CAIRO, ILLINOIS 
Davip H. THompson and GEORGE W. BENNETT 
Illinois Natural History Survey 
For many years the Illinois Natural History Sur- 
vey has been measuring fish populations and fish 
production. Among the various types of Illinois 
waters studied, it has been found that each tends 
to have the capacity to support a certain number of 
pounds of fish per acre which is constant from year 
to year. This number of pounds per acre remains 
constant even though there may be ten times as 
many fish (of one-tenth the average weight per fish) 
in some years as in others. When this amount of 
fish flesh per acre is disturbed by putting in or 
taking out fish or by floods or drouths, readjust- 
ment takes place much more rapidly than is popu- 
larly supposed. 
When a new lake is stocked with a few breeder 
fish the saturation point is usually reached in about 
a year. When one-fourth, or less, of the total 
amount of fish in a lake is removed during the 
course of a season, readjustment takes place so rapid- 
ly that changes in abundance are not detectable. 
This means that the yield of game fishes from an 
acre of water can be many times the amount taken 
out by ordinary fishing. 
Fish grow to more desirable sizes and furnish a 
better quality of food and sport when their numbers 
are reduced enough to give rapid growth rates. Good 
farmers understand this view of livestock and crop 
production and practice it continually. The follow- 
ing is an account of the changes which have taken 
place in Horseshoe Lake since its reconstruction in 
1931. 
DESCRIPTION 
Horseshoe Lake embraces about 2,400 acres of 
water with a 1,400-acre island in the center. The 
Illinois Department of Conservation owns the island 
and about two-thirds of the water surface and main- 
tains it as a waterfowl refuge. The lake is located 
about 12 miles northwest of Cairo on Highway 150. 
Horseshoe Lake is part of a former channel of the 
Mississippi which has grown up in cypress. Cypress, 
gum, willow and buck brush grow throughout all 
parts of the lake, although the trees are more scat- 
tering along the east side, leaving considerable areas 
of open water. With the exception of some flooded 
pasture lands, the remainder of the lake is grown up 
in timber and brush. The east side of the lake has 
a uniform depth of about six feet; the remainder is 
KINDS, SIZES AND NUMBERS OF FISH IN HORSESHOE LAKE 
Average Total Length in Inches 
Total No. 
Kind Handled 
1934-38 1934 
Warpemouth Bassi. ey oor ea 235 12.4 
WhitelCrappie ts fanig.c Sorter eee 1,044 10.3 
Black: Crappieaes. a7 cae = oe ee 3,913 6.3 
White Bass seeee. ate Oe ee ee 3 
YY ellow Bass’ 3). on nhs Gee 15 
Warmouth'Bass*.. oo oe 9 
Bluegill yo. ose ee ties ake aes eee eee 969 Thee 
Green: Sunfishs <5. 35 oe ti eee oe 2 
Flier:Sunfish 3. 22. ey a eee 825 Deo 
Grass Pikes< een eee ee eee 14 
Spotted: Gar’, a ae es Dr sewer 2 
Dogfish tA a eee eee eee ae 17 
Channel: Cat2: 5. = pee is Gee eee 9 
Black+Bullhead st. Wee ae ee eee 1,122 9.1 
Yellow sulheadis serene ee ee tee 329 10.8 
Gizzard (‘Shad Soycn ee eee cee eae 1,244 9.1 
Golden: Shiner.oG453"...5 oc he eis eee 11 
Carp false ater spas Ra SMa ee ere 217 19.8 
Redmouth buttalo.22 eee oe eee 618 13.8 
MonerellButialotene eet eee 33 15.2 
Smallmouth Sbultalo ese 12 
Quillback We. cee eee eee eee mae coe 9 
Redhorse2terr te ee ee aoe 1 
Spotted Suckers aya. geae ie rn ran 139 12.9 
GhubiSucker:taeccay aoe ee eee ee 1 
Total Seg ek ees Sd ee are 10,793 
Estimated Number in Lake 
during the Past Year 
1936 1937 1938 
16.2 15.4 16.2 5,000 to 10,000 
10.7 10.9 8.5 250,000 to 350,000 
7.9 7.6 7.9 500,000 to 700,000 
6.9 6.8 6.8 150,000 to 250,000 
6.0 5.8 5.9 4,000 to 15,000 
10.0 10.5 Bll 150,000 to 250,000 
10.9 12.1 11.4 35,000 to 50,000 
9.7 10.4 10.7 50,000 to 200,000 
20.8 21.5 22.6 25,000 to 50,000 
17.0 17.9 18.1 25,000 to 100,000 
20.3 22.7 21.7 1,000 to 5,000 
16.2 16.8 MV foll 5,000 to 20,000 
1,200,000 to 2,000,000 
=) 
