28 
BULLETIN OF THE BUREAU OF FISHERIES 
1926, in September, is but slightly higher than 1929 in Group I. Group II 
shows September at a very high level but this is probably an artifact, for in this 
group, since there was no fishing during September in 1926, the high 1929 year is 
compared to a standard curve considerably lower than would surely be the case 
were 1926 included. 
The curves for the whole four months’ period (fig. 13) show 1926 to be at a very 
high level of abundance; 1927 is at a very slightly lower level than 1928. In 1929 the 
Group I boats show a further decline, whereas 
the Group II boats show a large increase. 
This large increase probably is due in large 
part (as previously explained) to the lack of 
data for this group during September, 1926. 
From this analysis of the average size 
of the catches it must be concluded that 
1926 shows a much higher level of abun- 
dance than the three succeeding years. 
CHANGES IN NUMBER OF DELIVERIES 
Another method used in this attempt 
to determine the general trend of abundance 
was a study of the number of deliveries 
made by each boat each week . This method 
entails certain errors. When the fishing is 
being conducted at a distance the number 
of deliveries will necessarily be small; while 
when fishing close to the plant the number 
of deliveries will usually behigh, even though 
the catches may be small. During 1926 the 
number of deliveries each week has been 
multiplied by the factor 0.786, to make the 
data comparable to the following years in 
which there has been a 36-hour weekly closed 
season from 6 o’clock postmeridian Saturday 
to 6 o’clock antemeridian of the Monday 
following. These data were analyzed in the 
Figure i3. — showing the geometric means (expressed as same manner as the daily deliveries, the av- 
percentages of the 1928 mean) of the percentages that the number of deliveries Tier week beinp- 
average size of catch is of a standard curve (see text). era g e nUHlDer OI Convenes per WeeK Demg 
Solid line, Group I; dotted line, Group II; broken line, assumed to be the average for each day 
Group in within the week. Thus the standard aver- 
age on each day consisted of the arithmetic average of the average number of deliv- 
eries per week of the four weeks that happened to include the particular day. The 
results of the computations are shown in Table 5. 
