408 
BULLETIN OF THE BUREAU OF FISHERIES 
is limited almost wholly to the rate of growth of the O class; that is, from the time 
the fish are hatched in the spring until they leave the local waters in the autumn. 
The only published account of the rate of growth and the span of life of the 
pigfish known to the writers, is by Taylor (1916, pp. 319-324). Taylor’s discussion 
has for its basis a very limited number of length measurements and scale studies. 
It seems quite certain that Taylor, as stated elsewhere (p. 398) confused and combined 
the O class with older fish. 
His graph (fig. 7, p. 321, loc. 
cit.) shows a peak composed 
of fish 80 millimeters long. 
These fish, as shown by the 
graph (fig. 39), belong to 
the O class. Taylor’s graph 
does not show a clear divi- 
sion between the O class and 
older fish, because the meas- 
urements very probably were 
taken over a period of from 
two to three months (for 
Taylor’s investigation was 
carried on from the latter 
part of June until early in 
September ) and the data 
were not treated separately 
by months. Since the meas- 
urements were taken during 
a season of rapid growth, 
overlapping of the young, 
namely, the O class, with fish 
of the previous year would 
be expected over the period 
of time covered by the in- 
vestigation. 
In the present investi- 
gation, when much larger 
numbers of fish were meas- 
ured and the data analyzed 
separately for each month, 
the division between the O 
class and the older fish always 
was so obvious that it seems 
scarcely necessary to offer a 
frequency table as evidence. 
Prior to June the interval in the measurements of the recently hatched young 
and the older fish is large. Thereafter, it almost closes. Little, if any, overlapping 
occurs in the O and I classes, as previously indicated (p. 397); and, at most, only a 
few individuals could not be placed with certainty. 
The apparatus used for collecting young fish — namely, townets, small collecting 
seines, and small otter trawls — is not adapted to catching many large fish. How- 
flAR. APR. MAY J Util JULY AUG. SEPT. OCT. NOV. 
Figure 39.— Growth of pigfish (Orthopristis chrysopterus) during first summer. 
Solid line shows average size, dot-and-dash line illustrates maximum size, and 
dash line shows minimum size. (Based on Table 4) 
