264 
BULLETIN OF THE BUREAU OF FISHERIES 
collecting years that it may be possible to designate the year class as good or poor. 
The examination of the age composition of the different years’ collections in each of 
the four lakes (tables 45 to 48) does indicate the presence of certain year classes that 
can be termed relatively good or relatively poor. 
In the Trout Lake collections (table 45) the year classes of 1926 and 1927 appear 
to represent good years for the production of young. The former year class as the 
II group of 1928 made up more than half of that year’s collection, and 3 years later 
as the V group of 1931 it was still relatively abundant, comprising 13 percent of the 
total collection in this latter year. By reason of gear selection the 1927 year class 
(I group of 1928) was almost entirely lacking in the 1928 collections. This year 
class was, however, dominant in the collections of the later years, first as the III group 
of 1930 and then as the IV group of 1931. These conclusions as to the “goodness” 
of the 1926 and 1927 year classes are supported by the comparison of the relative 
abundance of corresponding age groups in the different years’ collections. The 1926 
year class furnished the greatest relative abundance of any II group in any year 23 
(56.0 percent of 1928 collection) and also of any V group (13.0 percent of the 1931 
collection). Similarly the 1927 year class furnished the greatest relative abundance 
of any III group (1930) and of any IV group (1931). It should be mentioned further 
that the presence of these two relatively successful groups contributed toward the 
progressive increase from year to year in the average age and average size of the fish 
in the collections obtained from Trout Lake. 
Table 45.- — Age composition of the samples of the Trout Lake cisco 
[The percentages are given in parentheses] 
Age 
ture 
i 
II 
III 
IV 
V 
VI 
VII 
VIII 
IX 
X 
XI 
XII 
1928 
2 (1. 1) 
102 (56. 0) 
61 (33. 5) 
17 (9.3) 
1929 
1930... 
36 (9.2) 
61 (10.0) 
247 (63. 2) 
173 (28. 4) 
99 (25. 3) 
269 (44. 1) 
9 (2.3) 
79 (13. 0) 
1931 
2 (0.3) 
12 (2. 0) 
4 (0.7) 
5 (0. 8) 
2 (0. 3) 
2 (0. 3) 
1 (0.2) 
In the Muskellunge Lake collections (table 46) the year class of 1928 (II group 
of 1930, III group of 1931) may be considered relatively successful. This year class, 
as the III group composed 55.6 percent of the 1931 collections, whereas in preceding 
years the III group composed a negligible portion of the total collection. The simi- 
larity of the age composition of the 1928 and the 1930 collections suggests the possi- 
bility that the 1926 year class may have been exceptionally abundant and that a 
collection in 1929 would have shown a high percentage of Ill-group individuals. 
However, the almost total absence of all age groups above the II group in the 1928 
and 1930 collections suggests also the possibility that heavy mortality may regularly 
reduce the numbers of Muskellunge ciscoes early in life, and that the great relative 
abundance of the III group in 1931 may depend not only on the great relative abun- 
dance of the 1928 year class but also in part on the failure of this year class to suffer 
this customary great mortality. The scarcity of I-group individuals in all Muskel- 
lunge Lake collections may be considered the result of selectivity by gear. 
23 The great abundance of II-group fish in 1928 may depend in part on the smaller mesh gill nets used in that year. 
