November, 1954 
when the opportunity arises. This loss of 
small fish is not considered serious; rather, 
in many situations it must be considered 
beneficial, because one objective of a bass 
management program is to bring the young 
fish up to desirable sizes as rapidly as pos- 
sible, and the thinning of a crowded popu- 
lation by loss of individuals over a spill- 
way would allow an improvement in the 
rate of growth of the fish remaining. That 
movement of young fish out of Ridge 
Lake may be random was indicated by 
the continuation of a crowded population 
of bass all through the 1942 season, al- 
though bass could have moved out of the 
lake over the surface spillway following 
seven or eight different storms that oc- 
curred in May, June, and July, fig. 5. 
The brood of bass spawned in Ridge 
Lake in 1941 had been reduced to four 
individuals by 1951, table 20. The age 
attained by these four bass is probably 
near the maximum for largemouths in 
the latitude of Illinois. For the 1941 
brood, the unaccountable loss, which in- 
cludes the loss resulting from natural 
deaths, was 39.1 per cent in the 1949- 
1951 period, whereas in the 1947-1949 
period it was only 9.8 per cent. 
The catches of bass for the individual 
years 1944 through 1950, which ranged 
from 31.0 to 62.4 per cent of the marked 
fish in the lake, table 19, may be con- 
sidered to represent high exploitation rates 
for a species of fish that has a normal life 
span of 8 to 10 years in the latitude of 
central Illinois. That these exploitation 
rates were not excessive for the Ridge 
Lake population was indicated by the fact 
that there was a comparatively high 
poundage of bass present when the lake 
was drained in 1951, table 7, after 7 years 
of these rates. It is true that in this 
period the yield of bass in numbers and 
total poundages, table 6, and pounds per 
acre, table 8, varied a great deal from 
year to year, but I can see no upward or 
downward trends in population abundance 
that can be clearly associated with rates 
of exploitation. 
So little information is available on 
exploitation rates of bass in other bodies 
‘of water that it is impossible to make a 
Eemparative evaluation of the exploitation 
rates at Ridge Lake. The high bass fry 
production in alternate years, table 9, was 
BENNETT: LARGEMOUTH Bass 1N RinpGE LAKE 
273 
important in that it assured adequate re- 
placements for fish caught, regardless of 
the exploitation rate. 
Today (June, 1954+) descendants of the 
435 bass with which Ridge Lake was 
stocked in 1941 are still rising to the lures 
of some of the fishermen who caught their 
great-great-great-grandparents in 1942, 
These present-day fish and the thousands 
that have inhabited the lake in the period 
since 1941 are mute evidence that the 
largemouth bass will respond to a few 
simple management techniques. The fish 
technician or the pond owner who knows 
when and how to apply these techniques 
need never worry for the future of bass 
fishing. 
Summary 
1. Ridge Lake, the dam for which was 
completed in April, 1941, is an artificial 
impoundment that at overflow level in 
1941 had an area of 18.1 acres and a 
maximum depth of 25 feet. It was made 
by damming Dry Run Creek, a tributary 
of the Embarrass River, in Coles County, 
Illinois. Both tower and surface  spill- 
ways were constructed. The tower spill- 
way was provided with a gate valve to be 
used in draining the lake basin. A perma- 
nent laboratory was built on the south 
shore of the lake about midway between 
the dam and the upper end. Silting of 
the lake basin was and is a serious problem, 
as much of the 902-acre watershed drains 
into the lake through steep-sided ravines, 
some of them pastured. The lake is 
eutrophic-like in character in that it has 
no dissolved oxygen in the deep water in 
summer, except when the cool oxygen- 
deficient water is flushed out of the lake 
through a tower spillway by the entrance 
of surface runoff into the lake basin after 
heavy rains. 
2. The lake was stocked in 1941 with 
435 bass, table 2, in 1944 with 129 blue- 
gills, and in 1949 with 138 warmouths. 
In 1942 and most subsequent years, the 
public was allowed to fish from boats be- 
longing to the Natural History Survey, 
and a record was made of kinds, numbers, 
and weights of all fish caught, table 6, 
time spent in fishing, table 15, kinds of 
baits, table 22, and the tackle used. A 
few scales were taken from each of the 
