24 
BULLETIN OF THE BUREAU OF FISHERIES 
and capacity has remained fairly 
constant. However, the capac- 
ity is based on the rated capac- 
ity of the press machinery. This 
machinery has been constantly 
improved, so that, whereas most 
of the presses of a few years ago 
could barely handle their rated 
capacity of raw fish, practically 
all of the newer presses (most of 
those now in use have been in- 
stalled since 1926) can slightly 
exceed theirrated capacity when- 
ever occasion demands. When 
the installation of more efficient 
cookers, meal dryers, fish con- 
veyors, etc., is considered, it can 
readily be comprehended that 
the rated capacity of the presses, 
our best measure of capacity, is 
too much in error to form an 
accurate basis of comparison 
from year to year. 
All of these facts tend to 
show that the actual capacity 
of the reduction plants has in- 
creased more rapidly than the 
number of boats. If this be true 
it is self-evident that in the ear- 
lier years the plants were more 
apt to be confronted with an 
oversupply of fish. This to some 
extent invalidates comparisons 
between earlier and later years, 
since whenever the plants have 
an oversupply of herring the 
catch per boat fails as a measure 
of abundance. At such times 
the curve of abundance is ab- 
ruptly truncated. The values 
obtained are minimum values, 
and there is no means of judging 
what the actual abundance may 
have been . No w if the c ap acity 
of the plants is raised, then at 
such times of great abundance 
the curve is truncated at a higher 
level ; so that in making compar- 
