PACIFIC HERRING 
313 
in the gill nets themselves, for during the early years of this fishery the fishermen 
used chiefly salmon purse-seine web of 3%-inch mesh (stretched measure). Their 
use at Halibut Cove is mentioned in the Pacific Fisherman as recently as April, 
1920. Residents of Halibut Cove say that since that time 3-inch mesh herring gill 
nets of finer twine were used exclusively. Although the points on the curve for 1921, 
1923, and 1924 are not based on many data, yet their close agreement lend them 
validity. The 1926, 1927, and 1928 points are based on ample data. The fall 
between 1924 and 1926 would appear to be rather too sudden to be caused by deple- 
tion (when the gill-net fishery had kept up so long) were it not for the fact that this 
is the period when the purse seiners commenced an intensive fishery just outside of 
Halibut Cove. We must conclude that the gill-net fishery in Halibut Cove presents 
strong evidence of a decline in the numbers of older fish. 
As mentioned above, all of the purse-seine and gill-net catches can not be accu- 
rately segregated, but since the great bulk of the take since 1924 has been caught by 
Figure 52.— The catch of raw herring and the gear used in Cook Inlet from 1924 to 1928, inclu- 
sive (see text) , plotted on a logarithmic scale to show the comparative rates of change. B roken 
line, number of purse-seine boats. Solid line, catch in millions of pounds 
purse seiners, the rates of change in the total amount of the catch and the number 
of purse-seine boats have been compared by plotting them on a logarithmic scale. 
(Fig. 52.) The data for the number of boats is subject to the following minor 
errors — to plus or minus one boat in 1924 and in 1925, and to the exclusion from 
the number of boats in 1928 of several that visited the district for short periods and 
left because of lack of fish. The errors in 1924 and 1925 are too small to be regarded. 
In 1928 those boats making short stays in the district were excluded so as to allow 
no personal judgment to creep into the analysis as to which boats could be said to 
have actually fished in the district. In 1924 and 1925 the boats and the catch 
increased at practically the same rate. Since then the catch has decreased at an 
average rate of over 35 per cent each year, while the boats continued to increase 
until 1927, then decreased between 1927 and 1928 although at a lower rate than the 
catch. From the evidence afforded by this analysis of the purse-seine catch it must 
be concluded that the Cook Inlet fishery shows a decline in abundance. This is 
substantiated, as mentioned above, by the failure of the gill-net fishery. 
Shuyak Strait . — For Shuyak Strait the catch and the number of boats are 
shown in Figure 53. They have not been plotted on a logarithmic scale because it 
is felt that in this instance the two are proportional only within certain limits. All 
