SOUTHEASTERN ALASKA SALMON STATISTICS 
659 
gear have undergone marked development during the period under consideration. 
In the case of purse seines there has been, perhaps, not so much change in the char- 
acter and effectiveness of the nets themselves as in the boats from which they are 
operated. In general these boats are larger and much better powered now than in 
the earlier years in spite of recent regulations which have limited the size of boats 
which may be used in purse seining. In the case of traps, improved construction 
has made it possible to operate successfully this apparatus in exposed positions that 
could not possibly have been used before and the development of the floating trap 
has made trap operations possible in places where pile traps could not be driven. 
Some of these improvements are reflected in the increased number of traps, but there 
have been general improvements in trap construction which have probably effected 
the relative efficiency of practically all traps in the district and which cannot pos- 
sibly be measured. It is safe to say, however, that both traps and purse seines have 
been increasing gradually in effectiveness as fishing units. 
The changes that have taken place in respect of the types of gear used have been 
notable. They are shown graphically in figure 54 as ratio diagrams so that the rela- 
tive changes in the use of the different forms will be clearly shown. (In a ratio dia- 
gram of this sort equal slopes indicate equal relative changes.) It is apparent that 
the number of beach seines and gill nets in use has been greatly reduced in recent 
years while the number of traps and purse seines steadily and rapidly increased from 
1904 to 1920. The reduced fishing effort in 1921, which has been mentioned repeatedly 
above, is shown clearly by the greatly reduced number of all forms of gear in use in 
that year. Since 1921 the number of purse seines used, up to 1927, was about the 
same as in the years 1916 to 1920, and the number of traps increased regularly until 
more were operated in 1926 and 1927 than in any previous year. 
While it is clear enough that important changes have taken place in the char- 
acter of these fisheries it is obviously impossible, with the data at hand, to arrive at 
any satisfactory conclusion as to the effect that these changes have had upon the 
real intensity of fishing. There can be no doubt that this intensity has increased 
enormously, but the lack of any information as to the relative effectiveness of the 
different types of gear, of the relative effectiveness of the same type of gear at differ- 
ent times, and of the effect of competition between units of gear as the number has 
increased make it quite impossible to measure the changes in intensity of fishing as a 
whole. 
Turning now to a consideration of the total catch of each species in southeastern 
Alaska it is apparent that different tendencies are shown by the different species. 
The total catches are shown graphically in figure 55 which, like the graph showing 
the changes in gear, is presented as a ratio chart so that relative changes may be 
correctly inferred. 
The catch of red salmon increased rapidly between 1885 and 1890 and formed by 
far the most important product of the fishery up to about 1895. For the next 10 
years the catch of this species continued to increase and then for 15 years, up to and 
including 1920, maintained a fairly constant level; 1921, as usual, showed a greatly 
reduced catch and from 1922 to 1927 the average catch was not much more than 
half that for the period 1905-20. The catches since 1921 doubtless have been 
affected somewhat by the regulations, but in view of the undoubted increase in the 
intensity of fishing, the fact that the catch of other species was increasing rapidly 
during the time (1905-20) that the catch of reds was relatively constant and that the 
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