276 
BULLETIN OF THE BUREAU OF FISHERIES 
tion of each year. The final figures after a combination of the sexes (table 55) indi- 
cate that growth in 1923 was 3.3 percent above average. Although the Clear Lake 
data of table 55 were obtained by a different method from the data pertaining to 
the other three lakes, the fact that all these “deviations from average growth” are 
used only to show relative positions of the different calendar years makes a compari- 
son of the data of all four lakes valid. 
The data of table 55 are presented graphically in figures 6 to 8. The examina- 
tion of the curves reveals a certain degree of correspondence as to goodness or poor- 
r 
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1923 1924 1923 1920 1927 1926 1929 1930 1931 
Figure 8.— Relationship in different calendar years between the deviation of growth of Clear Lake cisco from average and deviation 
of air temperature from normal during cisco’s growing season. Deviation from average growth, broken line; deviation from 
temperature, solid line. 
ness of growth for certain populations and over certain periods of years. For example, 
Trout, Silver, and Muskellunge Lakes agree in showing improvement in growth from 
1928 to the relatively good year 1929, followed by a distinct drop to the relatively 
poor year of 1930. Similarly Trout, Muskellunge, and Clear Lakes agree in showing 
poor growth in 1926 and 1927. 
Agreements of the sort just pointed out suggest that the amount of growth in 
different calendar years may possibly be determined in part by factors that affect 
all four lakes. The failure of any general agreement of the growth deviation curves 
indicates, however, that local conditions that exist within a single lake also exert 
a powerful influence on the amount of growth in different calendar years. 
The most apparent influence that might affect growth similarly in all lakes is 
the average temperature during the growing season, while growth within a single 
