AGE AND GROWTH OF THE CISCO 
259 
of the nets was again shifted, this time to depths of 7 meters and shallower. The 
catch on August 29 was: 60 perch, 13 suckers, 8 smallmouth black bass, 3 rock bass, 
and only 13 ciscoes. Thus it may be seen that at the end of August 1930, ciscoes 
occurred on the bottom in abundance only within a rather limited region. They 
were not plentiful in depths less than 9 meters and were absent in the deeper portion 
of the hypolimnion. 
Most of the ciscoes collected from Muskellunge Lake in 1931 were taken in a single 
set made July 14 at a depth of 9.5 to 10 meters. Although there are no 1931 data 
that may be used to set the upper and lower limits of the vertical range of the Muskel- 
lunge Lake cisco in that year, nets set at depths less than 8 meters for the capture of 
other species failed to take ciscoes. 
The results of the rather extensive fishing of the 1932 collecting season (table 40) 
give the most complete information concerning the vertical distribution of the cisco in 
Muskellunge Lake. From these samples which were taken at different times in 
July and early August it appears that approximately two-thirds of the fish were 
captured in nets set at depths between 11 and 13 meters (the fish were taken in the 
stratum of water 6 feet thick immediately above the bottom). Data on the 0 2 and 
temperature conditions in Muskellunge Lake in the late summer of 1932 based on the 
results of a vertical series of temperature and 0 2 concentration determinations made 
August 25 (table 41) offer an explanation of the concentration of the cisco into such a 
narrow stratum and suggest that such a concentration most probably occurs every 
year. The data of table 41 indicate that in Muskellunge Lake in late summer, oxygen 
is almost completely lacking in the hypolimnion and may be abundant in the upper 
part only of the thermocline. As a result of this deficiency of oxygen in the deeper 
strata the ciscoes are forced out of the cooler strata and by reason of their preference 
for cool water and their need of oxygen become concentrated in that stratum of water 
that has the lowest temperature available and yet contains sufficient oxygen to 
support life. 
Table 40. — Muskellunge Lake cisco, 1982 — Vertical distribution of the cisco 
[The data show the catch per day’s fishing of 100 square yards of gill net, set at different depths. In parentheses are given the 
number of lifts upon which each average lift was based] 
Depth in meters 
Size of mesh (in inches) 
Depth in meters 
Size of mesh (in inches) 
154 
m 
m 
1)4 
1H 
Less than 5 
5 to 7 
0.0 (1) 
.0 (1) 
.8 (5) 
10.3 (6) 
0.1 (10) 
.1 (9) 
11.2 (4) 
29. 0 (6) 
0.1 (9) 
.0 (10) 
.5 (4) 
1.5 (10) 
11 to 13.... 
13 to 15 _ 
42.0 (1) 
1.5 (2) 
21.5 (2) 
93.4 (5) 
17.0 (1) 
26.3 (3) 
0.5 (2) 
7 to 9 
No depth record. 
• 0 (2) 
9 to 11 
Table 41. — Muskellunge Lake, Aug. 25, 1932 — Relationship of temperature and dissolved oxygen to 
depth 
[Os in milligrams per litre] 
Depth in meters 
Temper- 
ature in 
° C. 
O, 
Depth in meters 
Temper- 
ature in 
° C. 
Os 
Depth in meters 
Temper- 
ature in 
° C. 
Os 
0 
21.3 
8. 02 
10 
14.5 
5. 33 
15 
10.5 
0. 56 
5.... 
21.3 
8. 70 
11 
13.8 
2. 67 
19 
10.1 
.24 
8 
20.7 
8. 25 
12 
12.0 
.43 
