740 
BULLETIN OF THE BUREAU OF FISHERIES 
SEASONAL OCCURRENCE OF EACH SPECIES 
PUGET SOUND FISHERY 
In certain areas several species of salmon may be present in considerable numbers 
at the same time, and during parts of the season a single purse-seine haul usually 
contains all five species. The seiners are able to make a certain amount of selection 
as to the species they wish to catch, however, by operating in different localities. 
In order to determine 
the seasonal progression of 
the various species in the 
fishery, the average daily 
delivery, by 7-day periods 
for each year from 1911— 
34, was calculated for each 
of them ; data from all ves- 
sels of 10-39 net tons being 
used. The 7-d ay averages 
over the 24-year period 
were then calculated, and 
determined as percentages 
of their sum (see table 17 
and fig. 17). The curves 
do not show the relative 
week ending abundance between spe- 
Figure 17. — Seasonal occurrence of the various species in the catch of Puget Sound cies but indicate for each 
purse seines. . . 
species the average pro- 
portion appearing in the catches of successive weeks during the fishing season. The 
pink-salmon curve represents occurrence only in odd-numbered years. 
Although there is considerable overlapping in the time when the various species 
appear, a distinct progression throughout the season is apparent, and the peaks of 
the runs of all species, except king salmon, occur at intervals of 3-4 weeks. These 
curves correspond closely to those from the trap fishery. The more prolonged periods 
of abundance of the various species indicated by these data may be attributed to the 
ability of the seiners to move with the fish, making their catches in whatever region 
that affords the greatest abundance at any particular part of the season. 
