AGE AND GROWTH OF THE CISCO 
261 
Table 42. — Silver Lake, Aug. 28, 1981 — Relationship of temperature and dissolved oxygen to depth 
[Oj in milligrams per litre. From Juday and Birge (1932)] 
Depth in meters 
Temper- 
ature in 
°C. 
Oi 
Depth in meters 
Temper- 
ature in 
0 C. 
0 2 
Depth in meters 
Temper- 
ature in 
° C. 
Oj 
7- 
20.2 
9. 20 
11 
9.4 
9. 80 
14 
7.7 
1.60 
8 
18.8 
9.90 
12 
8.6 
7. 50 
15 
7.2 
.60 
9 .. 
14.7 
13.20 
13 
8.2 
4.40 
18 
6.8 
.00 
10 
11.4 
11. 70 
The field records of lifts of ciscoes in Clear Lake indicate that in this lake the 
cisco occurs in all parts of the hypolimnion from midsummer to early autumn. 
(The dates of collection were July 22 to 28, 1931, Sept. 3 to 5, 1931, and July 12 
to 19, 1932.) This distribution of the cisco in Clear Lake suggests that it may at all 
times find a plentiful supply of oxygen throughout the hypolimnion. Such an 
assumption is supported by the data on the temperature and dissolved oxygen con- 
ditions in this lake based on a vertical series taken August 19, 1932 (table 43). 
These data show that at this time of the year there is in Clear Lake a plentiful supply 
of oxygen at all depths. Thus it is valid to assume that the net samples captured at 
different depths in the hypolimnion may be taken to represent the relative abundance 
of the cisco in Clear Lake. 
Table 43. — Clear Lake, Aug. 19, 1982. — Relationship of temperature and dissolved oxygen to depth 
[0 2 in milligrams per litre] 
Depth in meters 
Temper- 
ature in 
0 C. 
0 2 
Depth in meters 
Temper- 
ature in 
0 C. 
0 2 
Depth in meters 
Temper- 
ature in 
0 C. 
0 2 
0 
20.9 
8. 07 
12 
12.4 
9.46 
23 
8.4 
4. 51 
5 
20.9 
7.91 
15 
9.9 
7. 93 
26— - 
8.0 
3.25 
10 - 
18.5 
8.07 
20 
8.6 
6.03 
The data for the comparison of the relative density of the four cisco populations 
(table 44) represent the catch of 100 square yards of gill net fished over a period of 
24 hours. The lifts upon which the data are based were all made from depths at 
which the cisco occurred in abundance at the time of capture. These depths include 
the entire hypolimnions of Trout Lake and Clear Lake and the 10.5-15.5 meter 
stratum of Silver Lake, while in Muskellunge Lake the depths were 9 to 1 1 meters 
in 1930, 9.5 to 10 meters in 1931, and 11 to 13 meters in 1932. 
Table 44. — Catch in number of ciscoes per 100 square yards of gill net per 24 hours’ fishing 
[Data arranged according to lake, year of capture, and mesh of net] 
Lake 
Year of 
capture 
Size of mesh 
IK 
IK 
m 
2 
2K 
2K 
3 
J1930 
104.8 
73.0 
106.1 
143.9 
93.4 
31.6 
30.0 
1.4 
.9 
11931 
(1930 
> 61.0 
1 1.0 
2.8 
<1931 
(l932 
11930 
' 42.0 
1 .5 
50.0 
45.0 
3.5 
.7 
Clear 
11931 
J1931 
(1932 
1 62.0 
.1 
# 2 
> 76.0 
2.3 
1.9 
3.7 
2.4 
5.5 
4.3 
7.5 
3.8 
1 This size of mesh was not represented in the gear of the preceding years. 
1 The data for the 1932 Muskellunge Lake collections are presented in detail in table 40. 
