812 
BULLETIN OF THE BUREAU OF FISHERIES 
The southern pink-salmon index is very different from the northern (see table 
53). There was no fall after 1913 because the Hells Gate slide, which so seriously 
affected the northern run, had, of course, no effect on the spawning grounds of the 
southern run. 
From 1915-33 the two indices differ at many points, the northern index not 
showing the extreme fluctuations of the southern. In 1919 the southern abundance 
was extremely low, possibly due to the intense fishery of 1917. The highest point 
reached was in 1931. In this southern district our data show no depletion within 
a recent year. 
Table 53. — Pink salmon index of abundance from traps south of Deception Pass, 1907-33 
Year 
Catches 
Efficiency 
weights 
Number 
of traps 
Index of 
abundance 
Year 
Catches 
Efficiency 
weights 
Number 
of traps 
Index of 
abundance 
1907 
1909 
400, 054 
185, 762 
2 
215. 358 
1921 
1923 
223, 143 
495. 933 
134, 863 
432, 280 
3 
7 
165. 459 
114. 725 
1911 
314, 603 
290, 426 
134, 375 
338, 059 
397, 919 
3 
108. 325 
1925.. 
254, 732 
492, 875 
432, 280 
432. 280 
7 
58. 928 
1913 
1.54, 210 
531, 439 
432, 541 
49, 891 
1 
114. 761 
1927 
7 
114. 018 
1915 
5 
157. 203 
1929... 
485, 619 
813, 810 
334, 525 
432, 280 
239, 527 
290, 914 
7 
112. 339 
339. 757 
1917-.. 
6 
108. 701 
1931 
4 
1919 
397, 919 
6 
12. 538 
1933 _... 
5 
114.991 
ABUNDANCE FROM PURSE-SEINE CATCHES 
The purse-seine catches have been a fairly reliable guide to the abundance of 
pink salmon in Puget Sound since 1911, except in 1913 and to some extent in 1917, 
as they were usually the chief object of the summer seine fishery. To measure the 
abundance the average catch per seine boat delivery has been employed, using all of 
the catches made from August 5-September 8, inclusive, these 5 weeks taking in 
all of the important part of the season. 
Because of the difference in efficiency between purse-seine vessels of different 
size, the number of deliveries made by vessels of each 5-net-ton class was tabulated 
separately, and then weighted according to the efficiency scale for all species (see 
p. 738). The weighted numbers of deliveries for all sizes of purse-seine vessels were 
pooled, as were the catches, and the average catch per weighted delivery calculated 
(see table 54). 
Table 54. — Pink salmon abundance from Puget Sound purse seines 
Year 
Number 
of fish 
Number 
of 
catches 
Weighted 
number of 
catches 
Average 
catch 
1911 
441,920 
194 
175.6 
2, 516. 63 
1913 
471,627 
272 
301. 3 
1, 565. 31 
1915... 
1, 059, 304 
1,558 
1, 866. 2 
567. 63 
1917... 
763, 626 
705 
898.3 
850. 08 
1919 
251,337 
272 
391.0 
642. 81 
1921 
699, 099 
982 
1, 408. 0 
496. 52 
Year 
N umber 
of fish 
Number 
of 
catches 
Weighted 
number of 
catches 
Average 
catch 
1923. 
1, 493, 749 
1, 514, 755 
1, 136 
1, 621. 7 
921. 10 
1925 . 
745 
1, 067. 4 
2, 181. 5 
4, 546. 0 
1, 419. 11 
1927 
1, 800, 778 
3, 686, 797 
3, 399, 825 
3, 677, 705 
1, 497 
825. 48 
1929 
3, 019 
3,678 
5,003 
811. 00 
1931. 
5' 765. 5 
589. 68 
1933 
7, 719. 3 
476. 43 
COMPARISON OF PURSE SEINE AND TRAP INDICES 
The indices of abundance from Puget Sound purse seines and northern traps 
are compared in figure 29. The similarity between the indices is striking, as in only 
2 out of 12 years do they show any degree of divergence, namely 1913 and 1925. 
