SALMON AND SALMON FISHERIES OF SWIFTSURE BANK 
811 
catch in the past 10 cycles. Therefore, we must conclude that a tremendous decline 
in the abundance of pink salmon took place between 1913 and 1915. 
INDICES OF ABUNDANCE FROM TRAPS 
Because of the great dilforence in the time of the run between the northern and 
southern pinks, separate indices were made for the two districts. For the district 
north of Deception Pass 31 traps were selected fishing in the 14 odd years between 
1907 and 1933, and taking 21,051,873 pinks, up to and including September 8 of each 
year. To use a longer season was impractical as the traps did not fish late during the 
early years and were subjected to a 10-day closed period from September 6-15 in the 
later years. 
The 31 traps selected were distributed as follows: Point Roberts 3, Boundary 
Bay 9, Birch Bay 6, Lummi Island 4, Salmon Bank 4, South Lopez 2, Rosario, Waldron 
Island, and Haro Strait areas 1 each. The index was calculated in the same manner as 
described for sockeye. For a standard curve 12 traps were used, 3 each from Boundary 
Bay and Birch Bay areas, 2 each from Lummi Island and Salmon Bank areas, and 
1 each from Point Roberts and Rosario Strait areas. The standard covered the years 
from 1911-31. 
For the southern district only 7 traps were available, 2 from Middle Point area, 
2 from Admiralty Bay, and 3 from Bush Point. For a standard curve all 7 traps were 
used for the 4 odd years from 1923-29. 
The northern index (table 52) shows a tremendous fall in abundance after 1913. 
In 1911 and 1913 the index was 284, in the following 20 years, 10 odd years, it has 
averaged 67.7 or about 24 percent of the former level. 
The reason for this sudden drop in abundance can best be explained by the 
following quotation from the Report of the British Columbia Commissioner of 
Fisheries for 1915: 
. . . That there would be a great decrease in the run of pink salmon to the Fraser River 
District this year was clearly indicated in the Department’s report from the spawning grounds in 
1913. Owing to the blockade in the canyon of the Fraser at Hell’s Gate in 1913, no pink salmon 
were able to reach the spawning-beds in the waters above that point. Up to that year countless 
millions spawned in the Thompson and Nicola Rivers and in the vicinity of Seton Lake. As is 
shown in our report for the spawning-beds this year, no pinks reached those waters. 
Since, as pointed out above, the pinks invariably mature at two years of age, the 
very abundant odd-year run of pinks spawning in the Fraser River above Hell’s Gate 
Canyon was completely wiped out. 
Table 52 .-—Pink salmon index of abundance from traps north 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 
1, 103,010 
1, 220, 370 
4, 136, 212 
689, 171 
343, 969 
1, 453, 493 
1, 225, 884 
1, 833, 634 
1, 713, .587 
1, 557, 144 
10 
203. 579 
1921. 
967, 059 
1, 354, 003 
937, 627 
1, 731, 927 
1, 556, 160 
1,581,422 
1, 556, 160 
1, 500, 928 
1,520,336 
1,394, 611 
30 
65. 837 
1909 
5 
354. 791 
1923.. 
26 
87. 009 
1911 
24 
284. 570 
1925 
27 
59. 290 
1913 
i 487, 853 
909, 462 
1, 517, 903 
988, 092 
20 
284.517 
1927 
1, 395', 948 
947, 559 
1, 262, 263 
524, 512 
26 
89. 705 
1915 
31 
49. 599 
1929 
27 
63. 132 
1917. 
29 
88. 580 
1931 
24 
83. 025 
1919 
25 
63. 455 
1933 
23 
37. 610 
