HERRING IN PRINCE WILLIAM SOUND, ALASKA 
275 
Graphing these seasonal variations in yield in a different way, Figure 7 shows 
the cumulative per cent curve of the average daily catch per boat computed by 
10-day periods. During the first 6 of the 19 periods (from May 26 to July 24), 
49 per cent of the season’s catch is taken; during the last 6 periods (from Oct. 3 
to Dec. 1) only 7 per cent. Approximately 75 per cent of the seasonal catch is taken 
before the 1st of September. 
The histogram of Figure 7 shows the first differential of the cumulative percent- 
age curve, giving the percentage increments occurring during each period. The 
largest increments occur from the third through the seventh periods, remaining 
PEP/ODS 
T JUNE I JULY I AUGUST I SEPT. I OCT. I NOV. I 
Figure 7.— Average cumulative per cent curve of the catch per 10-day period, from 1923 to 1930, inclusive. Histogram at base 
shows the percentage increments for each period 
almost constant at about 10 per cent of the seasonal catch. Therefore, regulations 
prohibiting fishing during any portion of these periods would curtail the catch 
more than a proportional cut in time during any other part of the season. 
During the late summer and early fall, the runs of herring have proven to be 
erratic, varying widely from year to year from the norm established over the period 
of eight years for which data are available. (Table 8.) The autumn run, which 
is evidently a normal condition in the fishery, was unusually abundant in 1930, 
being one of the chief factors in the increase in total production of 1930 over 1929. 
In 1929 the fall run did not appear, even though both years depended almost 
entirely on the same year class. This would indicate that the magnitude of the 
autumn run depends to a very large extent on some factor or factors other than 
the abundance of herring. 
