72 
BULLETIN OP THE BUREAU OF FISHERIES 
tierce is the equivalent of 25 cases of canned fish. Pubhshed data are not available 
to show that this is a fair procedure, but it is believed that it gives a very close 
approximation to the truth. It is stated by Cobb (1921) that the loss in weight of 
mild-cured salmon "during the 2 or 3 weeks in which the fish lie in the first packing 
may be reckoned at 30 per cent." Packers on the Columbia River usually estimate 
that chinooks lose about 25 per cent of the round weight in cleaning preparatory 
to canning. Although the loss is probably a little more in the case of the fish that 
are mild cured, on account of the removal of the backbone, the figure is close enough 
for practical purposes. If, then, the weight of the cured fish is 70 per cent of the 
cleaned weight, and the cleaned weight is 75 per cent of the round weight, the total 
loss in weight during the entire process is 52.5 per cent of the roimd weight. It 
would therefore require 1,600 pounds of round fish to produce a tierce containing 
830 pounds of mild-cured salmon. Canners on the Columbia River consider that 
it usually requires about 65 poxmds of round fish to produce a case of canned fish, 
and on this basis 1,600 pounds would produce very close to 25 cases. 
The Columbia River salmon fishery has for years been prosecuted with an 
intensity that makes it seem remarkable that a run of commercial value still remains. 
Figures, unfortunately, are not available to show how this intensity has increased 
since the beginning of the industry, but there can be no doubt that there has been 
a tremendous increase in the total fishing effort within the river. There has been 
not only an increase in the number of men, boats, and various units of gear, but 
a marked increase in the effectiveness with which the gear is employed. The motor 
boat has, within the last 20 years, replaced the slower sailboat, and the length of 
gill nets and seines and the size and effectiveness of fish wheels has increased. The 
fishing inside the river was, at the time the outside fishing first began, about as 
intensive as possible. Practically all good trap and wheel sites, seiniag grounds, 
and '"drifts" in which gill nets could be operated were occupied. The discovery 
that salmon could be caught profitably outside the mouth of the river by trolling 
and in purse seines offered, therefore, a new avenue of expansion in which the 
fishermen so engaged did not come into direct and immediate competition with 
those already established on the fishing grounds in the river. It was found that 
the area in which such fishing could be carried on was wide, trollers ranging 20 to 
30 miles in all directions from the niouth of the river. Such a broad region offered 
large possibilities for expansion and, since the outside fishing proved lucrative, it 
is not surprising that fishermen flocked to the new fields. Since this has not been 
accompanied by any appreciable reduction in the fishing effort within the river, it 
has meant a sudden and great increase in the total fishing effort directed against 
the sahnon run of the Columbia River. Since a considerable portion of the total 
pack of salmon in the river has come from fish caught in the ocean, it means, further, 
that a correspondingly smaller percentage of the total pack has come from inside 
the mouth of the river from gill nets, seines, traps, and wheels. 
From the evidence given above it is apparent that the immediate effect of the 
introduction of fishing methods that attack the immatiu'e fish found just off the 
mouth of the river is to increase the intensity of fishing, not only upon those salmon 
that are destined to mature and spawn during the year but also upon those that 
will form the spawning run the following year, and, to a more limited extent, the 
