254 
population of the lake. The survival of 
spawn in 1941 was very high, and the 
new lake contained adequate torage for 
these small bass throughout the 1941 
growing season, so that their growth rate 
in 1941 was rapid, table 12, even though 
the lake basin did not completely fill 
until December. 
In four collections in the spring of 
1942, consisting of a total of 148 fish, 
21.6 per cent of the bass were 10 inches 
or longer; on the basis of this sample, it 
was decided to open the lake to fishing 
in the summer of that year. 
In the fishing season of 1942, anglers 
took 323 bass of 10 inches or longer be- 
longing to the 1941 brood, table 6, and 
released 3,604 smaller fish they had 
caught. Apparently the larger fish were 
the cannibals of the brood. It was not 
until the draining census of 1943, after 
the fish of the 1941 brood had completed 
two growing seasons, that the average 
length in the brood could be placed accu- 
rately; it was 7.6 inches, table 13. Scale 
studies support the hypothesis that most 
of this growth was made in 1941 and 
that the fish remained about the same size 
throughout 1942. Growth was resumed 
in the 1943 season at a relatively slow 
rate, following the spring reduction in 
population. It was not until late in the 
summer of 1944 that a large part of the 
1941 brood exceeded the 10-inch length. 
In the draining census of 1945, after four 
growing seasons, this brood averaged only 
11.5 inches total length. The condition 
of overpopulation and stunting of bass 
that existed in Ridge Lake early in 1942 
might have been quickly rectified had fish- 
ermen been allowed to take the 3,604 bass 
of less than legal length (10 inches) that 
were caught and released in that year. 
As mentioned in the section “Spawning 
Success and Population Density,” very 
few bass of the 1942 and 1943 broods 
survived the postfry stage. The first brood 
of bass after that of 1941 to be repre- 
sented in anglers’ catches by fair numbers 
of fish was that of 1944. Ninety-two fish 
of this brood unexpectedly appeared as 
unmarked individuals in the hook-and-line 
catch of 1946. The survival of 1944 
brood fish, supposedly removed from the 
lake in the draining operation of 1945, 
may be theorized as follows: Bass of the 
Ittinois NaturAL History Survey BULLETIN 
Vol. 26, Art. 2 
1941 brood were about 10 inches in length 
in 1944 and were not particularly inter- 
ested in bass fry as food. Few bass of 
smaller sizes (1942 and 1943 broods) 
were present. Bluegills were placed in 
the lake in June of that year and imme- 
diately produced a large spawn. The small 
bluegills may have acted as a buffer, re- 
ducing bass predation on bass. The upper 
Table 12.—Numbers of 1941 brood of large- 
mouth bass of various lengths taken with 
fly-rod lures at Ridge Lake, on August 20 
and on October 14 and 21, 1941. 
Tora. NuMBER gels 
LENGTH, TAKEN, O a 
INCHES Avucust 20 Argos 
ie my Giese pane 0 0 
SU sie erse eae 1 1 
ND Eo Ne 3 2 
CR 2 9 
be Coady 1 1 
Dh eae Ee atinse 1 0 
Rid yea 9 4 
Guo ea ke as 11 1 
7 AP ete Ye! See 9 2 
LA corneas 5 5 
b6. Retin it een oe 6 9 
Bape acacia: 2 11 
edie On eae 0 20 
QU 6 Sesame 0 9 
LOST ees, Eee 0 7 
LOGS Si) Ae 0 2 
otal sous seeks 50 83 
part of the lake had developed a dense 
stand of the pondweed, Potamogeton foli- 
osus, and other plants into which some of 
the 1944 brood bass moved and lived 
throughout the summer. Individuals of 
this group made poor growth (as shown 
by the scale pattern of the brood) be- 
cause of food competition among the fish 
within the mass of plants. At the end 
of the first growing season most of these 
bass were less than 2 inches in length 
(calculated from scale measurements at 
later dates). 
Some of the small bass of the 1944 
brood escaped the 1945 draining census 
by remaining in pools or in the blind 
stream channel between the mouth of the 
diversion ditch and the dam until after 
the draining census was completed and 
water was again impounded. These fish 
then escaped from the confines of the 
blind stream channel or the pools. As 
