Biology of the Aku — Brock 
97 
Fig. 2. Growth curve of Hawaiian aku. The number identifying modal lengths is the presumed year of origin 
of the modal group. 
15, 1946, to July 4, 1951, was calculated, as 
well as the average of all the modal lengths of 
the modal group composed of fish of the 
smallest size, for these same sampling dates. 
This average modal value was taken as length 
at age N, which was assumed to be 1 year, and 
the growth curve shown in Figure 2 was 
computed, using the equation for the least 
square fit obtained as described above. Shown 
also on Figure 2 are the various modal values 
from Table 1 for which the computed growth 
curve would seem to provide a good fit. 
The modal values obtained during the win- 
ter period were not used in the computation 
of the growth curve, as the mean sampling 
dates were usually much less than 6 months 
later than the mean sampling dates for sum- 
mer, and, in addition, the number of fish 
represented by the winter samples was often 
small. Again the mode of smallest-size fish 
occurring in the winter samples was not in- 
cluded in Table 1, as it was felt that fish of 
these sizes or a little less were discriminated 
against by the fishermen and that these modal 
groups sampled during the winter repre- 
sented, therefore, an incomplete part of the 
entering year-class. This judgment is, perhaps, 
strengthened by the fact that these particular 
modes do not seem to fit into the same pat- 
tern as the others. By summer the entering 
year-class would seem to be adequately rep- 
resented in the catch in that the modal 
positions found for it do fit into the pattern 
of modal lengths of the older fish. 
MODAL LENGTH AND AGE 
If the age of the year-class entering the 
fishery during the summer is assumed to be 
1 year, even though the growth attained dur- 
ing the first year seems high, it fits the pattern 
of growth which follows better than the as- 
sumption of some other age, such as 2 or 3 
years, which may otherwise seem likely. If 
the judgment made here of the age of the fish 
in the entering year-class is in error by a year 
or more, then the initial accelerating portion 
