246 
algae, and rooted aquatic vegetation, either 
submergent or emergent. For example, in 
1944, when the spawn estimate was only 
1,000 fry, table 9, and in 1949, when 
it was 24,000, the censusing operation 
was handicapped by mats of floating algae. 
In both of these years, the enumeration 
of young bass was continued, after the 
schools had broken up, by counting the 
fry scattered along the shore shelf. In 
1945, when the peak spawn was recorded, 
few floating algae were present, but dense 
beds of submerged aquatic plants (not at 
the time reaching the surface) were in 
the lake. In 1946 and in 1947, turbid 
water during the height of the spawning 
seasons so reduced the visibility that not 
until 3 or 4 days after the first schools 
were observed was it possible to make a 
comprehensive census. 
Despite many possible sources of in- 
accuracies, the fairly uniform technique 
of censusing that was continued each 
year after it was established in 1941 gave 
comparative data that are very useful. 
The results of bass fry estimates, 1941 
through 1950, were reported in a previous 
paper (Bennett 1951:237) and are re- 
peated in table 9, along with an estimate 
of the 1951 spawn and the actual dates 
when the first schools of bass fry were 
seen in each year. Table 9 has been set 
up in two sections to emphasize the strik- 
Intinors NaturaAL History Survey BULLETIN 
Vol. 26, Art. 2 
ing difference in the abundance of spawn 
between years in which the population was 
culled of small “yearling” fish (fish 
spawned the previous year) and years in 
which many of these fish were present. 
Although the numbers shown in table 
9 may be far from accurate, if these num- 
bers are taken as indices of the relative 
abundance of young bass from year to 
year, it is believed that they are highly 
significant. In 1941, when the lake was 
first stocked with adult bass and in years 
when the lake was drained and restocked 
with only the larger fish, the average of 
the estimated numbers of fry (50,500) 
was about 8.6 times the average of the 
estimated numbers of fry found in alter- 
nate years when the lake was not drained 
and the fish population was not culled 
of small “yearling” fish. The difference 
between average numbers would have been 
much greater if the spawn count of 1942 
had been omitted. The “yearling” fish 
present in 1942 (largely bass ranging in 
size from 6 to 11 inches) averaged larger 
than those present in any other compa- 
rable year (1944, 1946, 1948, or 1950). 
These bass were little interested in nest 
robbing or in predation on fish of fry 
sizes. hey decimated the 1942 spawn, 
but their predation is believed to have 
taken place after the 1942 bass fry had 
grown to fingerling sizes. 
Table 9.—Estimates of numbers of largemouth bass fry to reach schooling stage in 
years in which Ridge Lake fish population was culled of small “yearling” fish (fish spawned 
the previous year) in spring draining censuses, and similar estimates in years in which no 
draining censuses were made and many small “yearling” fish were present. The earliest dates 
on which bass fry were observed are listed. 
Data For YEARS IN WuiIcH SMALL “YEARLING” Data For YEARS IN WHICH SMALL 
Fish Were REMOVED IN SprING DRAINING “YEARLING” Fish WERE PRESENT; LAKE 
CENSUSES Nor DraineD 
Year | Saupeniey anise Earliest Date Year | Estimated Number Rae Date 
oO Oo of o 
Bass Fry Fry Appearance Bass Fry Fry Appearance 
1940 7: 76,000! May 29 1942 26,000! May 14 
Tag 6s =, 18,000! June 10 1944 1,000! June 4 
PS is: 116,000 June 3 1946 2,500 June 5 
LF by Rea a 37,000 June 4 1948 0? None 
(2 0 eae 24,000 June 3 1950 0? None 
ae 15 Sees 32,000 May 25 — —_ = 
Tetel. es. 303,000 | — 29,500 =a 
Average... 50,500 — 5,900 =o 
1 Few fish other than largemouth bass were present in the lake. 
? No schools of young bass could be found in 1948 and 1950. Extensive seining with a minnow seine produced no 
small bass in 1948; 
in 1950, one small bass was taken in one of five minnow seine hauls in the upper part of the lake. 
