244 Intinois Naturat History Survey BULLETIN Vol. 26, Art. 2 
Table 7.—Pounds of fish, per acre of lake, taken in draining censuses of Ridge Lake 
and pounds, per acre of lake, returned following each census, 1943-1951. The area of the 
lake was assumed to be 18 acres. 
TAKEN IN Dratninc Census 
YEAR 
uarge- | 
mouth — Bluegills pie 
| » ‘Bass > | | ; 
1941 (original 
BEDEK) |. 5 ois Hinsenie “= — —_ 
hh ERE a A. Bp _ | (Viele 
SGEE sor No cas kh ee 7.0 Don 
1k y dare aaa Sede Pe ee Pe OS 3352 
BN8 eid 080 am 86.9 2.98 
| joy VE at fate 3 JR 105.2 8.74 
RetTuRNED FOLLOWING 
THE CENSUS 
| Total in Large- : War- 
re mouth Bluegills h 
ensus iat mouths 
os Sys! — — 
48.7 21.4 _ — 
123 28.7 1.4 — 
256.3 ely fn 15.8 — 
140.2 44.7 — _ 
163.8 42.4 Tes 2.9 
1 Black bullheads and green sunfish. 
2 Black bullheads, green sunfish, carp, and one black buffalo. 
2 Black bullheads, yellow bullheads, and green sunfish. 
* Warmouth bass, black bullheads, carp, and miscellaneous minnows. 
Table 8.—Pounds of fish per acre of lake (18 acres) taken by fishermen and fishing 
pressure at Ridge Lake, 1941-1950. 
PER ACRE 
YrieLp, Pounps 
YEAR | 
ea ane Bluegills 
OA Bact too i die eae Oo5 — 
EE VERE SS) Seats eel — 
LO ES age Aire simi aad 1.0 — 
MAAS FeO eens HS550 — 
IOS eee ale 19.8 0.1 
[Ko 2 Ee Bag Sartre 14.6 UPA] 
Se RS nip ieee Phan S| 6.2 
Rei ce cp ie ora: 2576 45.9 
ee Se te a a 30.0 0.2 
Re eine PE Teeg 18.3 6.7 
! 
FisHING PRESSURE, 
Green Black Man-Hours PER ACRE 
Sunfish Bullheads 
— — 212 
+2 2.0 90 
+2 0.3 105 
1.8 0.8 168 
0.2 0.1 155 
1.9 3.9 320 
— +2 220 
0.53 4.2 224 
1 Lake not open to public fishing in this year. 
2 Less than 0.1 pound per acre. 
® Consists of 0.3 pound per acre of green sunfish and 0.2 
ably were much below the potential maxi- 
mum. 
In a review of table 7, this question 
may immediately arise: If a determi- 
nation could be made of the maximum 
poundage of each of several fish species 
that can be supported individually by a 
lake, and then if all of these species could 
be placed together in the lake, what would 
be the relationship between the maximum 
poundage of this composite population of 
fishes that can be supported by the lake 
and a summation of the maximum pound- 
ages of fishes supported by the lake as in- 
dividual species ? 
The data in table 7 cannot give a satis- 
pound per acre of warmouths. 
factory answer, but they advance the 
suggestion that, while the diversification 
of species may improve the degree of 
utilization of available food and space and 
thereby add to the poundage of fish the 
lake can support, the maximum poundage 
of a composite population will be con- 
siderably less than the summation of the 
maximum poundages of individual species. — 
Even in a bass-bluegill combination in 
which, in theory, the young of the blue- — 
gills should improve the food supply of 
bass, there is no evidence from this study _ 
that the bass population is able to expand — 
to a poundage significantly greater than — 
the lake supports when bluegills are ab- 
