MIGRATION OF SALMON IN COLUMBIA RIVER. 
135 
the greater portion of its length. A fold of the burlap was so arranged that it could 
be quickly thrown over the middle portion of the body of the salmon whenever desir 
able, i. e., occasionally with the largest specimens. 
When a fish was laid out on the measuring platform the tip of its nose was allowed 
just to touch the vertical piece and its tail was extended to full length. The total length 
was then read off by the measurer and announced to the recorder. The tail was, how- 
ever, never released from the grasp of the operator during this move; a struggle is apt 
to begin at any moment, and if the fish struggles it must be swung free into the air to 
prevent pounding on the board and injury to itself. If the length was not caught by 
the measurer before struggling occurred, the process, of course, had to be repeated. 
Lifting a salmon from the water, taking it from the net, and reading its length on the 
measuring board really consumed only a very few seconds — not so long a time as 
required to describe the process. 
After the length was read the next step was the insertion of the marking button. 
This was done by the person who did the measuring. The buttons in this experiment 
were all inserted in the caudal fin. The upper lobe was used except in a few cases where 
a cleft was present, in which case the lower lobe was used for the button. The inserting 
tool, previously described, although intended for use on the domestic animals, was reason- 
ably workable on salmon. Its chief deficiency was in the fact that its use required two 
very different movements. The first movement was to slip the handle over the lobe of 
the fin in order to punch the hole for the button (see fig. 2). The second act was for 
the purpose of compressing the button and riveting it securely in place. If the fish 
began to struggle at the instant the button was being compressed, the button had to 
be released instantly lest it be torn from the fin. In cases where the tail was released, 
the unriveted button was usually thrown out and had to be reinserted. A special 
tool is being devised for future work that will punch the hole, insert the button, and rivet 
it home in one continuous movement. Such a tool will materially increase the rapidity 
of the work. 
The salmon that came through the marking process in good condition were imme- 
diately released overboard in the direction of the open water. If there was any ques- 
tionable degree of asphyxia, the fishes were released into the car and turned overboard 
only when fully recovered. In two fishes that were markedly asphyxiated it was neces- 
sary to use artificial respiration for a short time. Both v/ere strong and active when 
ultimately released from the live car. The fishes took the water readily and quickly 
swam away. My previous experience in handling live salmon enables me to state that 
the present handling was well within the limits of treatment which salmon endure 
without danger or risk. 
The weight of the fishes was estimated by Foreman Borkman, who has a reputation 
for skill in the accuracy of his judgments. Mr. Borkman’s estimates have come very 
close to the actual weights of certain of the fish retaken. In at least one of the largest 
fish the actual weight tallied exactly. The judgments of the weight were arrived at dur- 
ing the handling of the fish in the net and on the measuring board. These estimates 
