SALMON AND SALMON FISHERIES OF SWIFTSURE BANK 
777 
The returns from this spawning brought a run in 1921 only two-fifths as abundant 
as that of the parent year. The catch of 1,700,000 in 1921 was relatively a great 
deal less, for the abundance level, than that of 6,800,000 in 1917. Since 1921 this 
cycle has been very slowly recuperating, increasing about 25 percent in abundance 
by 1933, according to the combined index. Besides producing the best pack of the 
last 4 years of this cycle, 1933 also had the best spawning escapement since 1917. 
Especially worthy of note was the good escapement to the headwater lakes as compared 
to other recent years. For instance, over 100,000 are estimated to have reached 
Chilco Lake. A fair number reached the lakes of the Stuart system. The escape- 
ment to the Fraser-Francois Lake system was twice that of 1929 and for the first time 
in years numbers of sockeyes reached Burns Lake. 
Abundance of Cycle Ending in 1932 
The cycle of years, 1932, 1928, 1924, etc., immediately preceding the big years 
was the poorest of the 4 throughout the early years of the fishery, and in common 
with the other off years, this cycle commenced to decline before the beginning of the 
century. 
In 1900, while still at a fair level of abundance, this cycle was fished with extreme 
intensity, the gill-net effort being the highest in the whole history of the fishery and 
the number of sockeye traps as great as in the big year of 1901. The resulting catch 
of 4,400,000 was too great a proportion of the run, the abundance declining over 30 
percent by 1904. In 1904 the fishing intensity was greatly reduced, only 2,400,000 
sockeyes being taken, and the cycle recuperated. In 1908 the fishing intensity was 
again dropped, yet a larger catch of 2,700,000 was made. 
The abundance in 1912 was apparently as great as in 1908, as is shown both by 
the combined index and by the catch of 3,400,000 which was made with slightly more 
traps and about the same gill-net effort as the catch of 2,700,000 in 1908. Further- 
more, the proportion taken by the gill nets was much greater in 1912 than in 1908 
which might indicate a better escapement. This is confirmed by spawning-ground 
estimates that would certainly place 1912 ahead of 1908. 
The index of abundance fell 63 percent between 1912 and 1916. In 1916, although 
the number of traps was fairly low, the gill-net fishery was very intense, yet only 1,300,- 
000 fish were taken, and the unusually small proportion taken by the large number of 
gill nets would indicate a small escapement. The estimates show that it was probably 
the smallest escapement in the history of the fishery. 
Because the spawning of 1912 produced a run so very far below the average 
expectation for such a relatively good escapement, we are forced to conclude that the 
failure in 1916 was not caused by overfishing, but by some natural condition, pos- 
sibly connected with spawning, that greatly reduced the rate of survival. It is 
impossible, at this date, to know what all of the spawning-ground conditions were, but 
we have noted that the early months of 1913, when the eggs would have been incu- 
bating in the gravels of the spawning beds, were extremely cold. 
Average monthly temperatures from 1888-1930 at Barkerville and from 1891-1930 
at Kamloops were studied. These two points were chosen for having long series of 
observations and for being close to the spawning grounds. For each locality the 
