AGE AND GROWTH OF THE CISCO 
293 
condition ( K ) and environmental factors. The data of this study indicate that the 
cisco is in the best condition in the most oligotrophic environment and in the poorest 
condition in the most eutrophic environment. However, the situation found in the 
Indian Village Lake (Indiana) shows that such a relationship cannot he considered 
general for this plastic species. Although the lakes of northeastern Indiana are of 
the extreme eutrophic type and the Indian Village Lake cisco lives under what are 
apparently the most undesirable conditions with respect to temperature and oxygen 
conditions (Scott, 1931), the Indian Village Lake cisco shows excellent growth and 
is in better condition than any but the Clear Lake population of this study (p. 249). 
FISHES ASSOCIATED WITH THE CISCO 
There is little resemblance among the fish associations of which the four cisco 
populations are parts. In table 70 are recorded the numbers of individuals of all 
species taken in the nets used for the cisco. Fish are considered to have been taken 
along with the cisco if they were taken in a net of any mesh set at the same time 
and approximately the same depth as the nets that caught ciscoes. 
Table 70 . — Numbers of individuals of other species of fish taken in the net catches along with the cisco 
samples 
Lakes 
Species 
Trout 
Muskel- 
lunge 
Silver 
Clear 
Cisco. j 
1, 197 
1, 863 
1, 543 
524 
465 
Perch . 
i 
5 
Pike-perch __ 
37 
Rock bass ... 
8 
1 
Sucker 
130 
Lake trout 
32 
Whitefish ... ... 
32 
Burbot 
1 
Smallmouth black bass _ _ 
14 
In Trout Lake the fish taken with the cisco were^all typical deep-water forms. 
There is no evidence that the deeper regions of the lake are invaded by individuals of 
the shallow-water forms. The trout were mostly large individuals that were caught 
and held by the teeth in small mesh nets. 
The situation in Muskellunge Lake is unusual. The close association of the cisco 
with shallow-water forms is the result of the deficiency in oxygen that drives the 
ciscoes up from the lower, cooler strata of the lake. 
In Silver Lake the cisco is practically isolated, at least during the late summer. 
The single perch taken at a depth of 14.5 meters may be considered a straggler. 
In Clear Lake the pike-perch that were taken regularly along with ciscoes appear 
to be distributed generally throughout the region occupied by the cisco in this lake. 
The five perch were taken at depths between 19.5 and 24.5 meters. The rock bass was 
captured at a depth of 15.5 meters. Since both rock bass and perch are known to be 
plentiful in the shallow water of this lake their presence in the hypolimnion may be 
considered more or less as accidental. 
In all the lakes the nature of the associations of which the ciscoes are part prob- 
ably undergoes considerable change according to the time of year. 
