767 
SALMON AND SALMON FISHERIES OF SWIFTSURE BANK 
On account of economic conditions only six canneries operated in 1884 and 1885; 
but the number of licenses issued was as great as in years when double the number of 
plants were busy. Therefore, the low points of 1884 and 1885 should be regarded 
with suspicion, as the catch per net was obviously lowered by the inability of the 
canneries to utilize their full catching capacity. Eliminating these doubtful years, 
1886 appears to be the low point of the early period. 
Since about 1897 the whole curve is lower than would be the case were the whole 
sockeye population to have reached the river, as it did before the expansion of fishing 
in Puget Sound. Regard- 
less, however, of all the fac- 
tors that presumably affect 
the level of the curve to 
some extent the fall is far 
too pronounced to mean 
anything but depletion. 
INDEX OF ABUNDANCE 
FROM TRAPS 
The salmon traps form a 
very reliable means of deter- 
mining the abundance of 
the sockeye, inasmuch as 
they were driven year after 
year in the same location; 
and, although the fishing 
ability of the individual trap 
may have varied somewhat 
from year to year, on ac- 
count of weather or tides, yet the decrease in the catch of one trap is apt to be compen- 
sated for by the increase in another if a sufficiently large sample is utilized. 
In making this index traps were selected from various localities so as to discount 
the effect of any slight changes in migration routes or any diminution of the numbers 
migrating past any one locality, which might be caused by hydrographic conditions 
or by sockeyes of different lake systems using different migration routes through the 
salt water channels leading to the mouth of the river. Of the 43 traps selected, 3 
were from the Point Roberts Area, 12 from Boundary Bay, 5 from Birch Bay, 4 from 
Lummi Island, 6 from Rosario Strait, 3 from the South Lopez Area, 4 from Salmon 
Banks, 1 from Waldron Island Area, and 5 from Haro Strait. No trap selected fished 
less than 10 years and 5 of them fished from 1898 to 1934, or 37 years, without a single 
break. They averaged 27 fishing years each between 1896 and 1934. The use of more 
traps would have given too much weight to the Boundary Bay Area which was already 
well represented. In most of the other areas all available traps were used to aid in 
compensating for changes in the route followed. No traps were used from West 
Beach as they also catch sockeyes bound for the Skagit River, but, as this area is a 
small producer of sockeyes, its omission can be of no consequence in determining the 
trend. 
Figure 23. — Annual catch per unit of fishing effort of Fraser River gill nets for the 
68-year period from 1877-1934. Note the decrease in the catch in each of the four cycles, 
These cycles are caused by the sockeye maturing predominately at 4 years of age. 
