TAGGING SALMON IN ALASKA, 1923 
31 
the discovery in them ofs ufficiently well-marked racial peculiarities to locate the 
migrants in the colony to which they belong. 
It was in the hope of accomplishing this in some measure that, in the 1923 
experiment, we made a prominent feature of collecting a full set of scales of all the 
sa lm on that were tagged. At the time each tag was attached a sample of the 
scales was removed and was immediately transferred to a specially prepared blank 
book, which was ruled in five spaces to the page, each space bearing a serial number 
identical with that of the tag. The material, then, includes the scales of some 
10,000 red salmon, so arranged that there can be singled out for critical study those 
belonging to any individual recaptured at the stream it was preparing to enter, the 
racial affinities of which it was desired to ascertain. Other results, which we were 
justified in anticipating, include the following : 
1. Some estimate of the intensity of the commercial fishing, based on the 
proportionate number of tagged fish that are recaptured. Such an estimate wil 
of necessity be a minimum. The percentage of the run actually captured will be 
greater than our estimate, for some of the tags unquestionably become detached 
and are lost although the fish are recaptured, some tags are taken by fishermen, 
and others are not reported; but as a minimum record the figures still have value. 
2. We may anticipate valuable information concerning the routes traversed, 
the association of races in a common wave of migration, and their segregation on 
approaching the streams for which they are bound. Still more interesting will 
be evidence that certain races take a distinct route from that followed by others 
that traverse the same general region. The existence of distinct ocean lanes for 
colonies still far from home opens wide grounds for speculation. 
3. The rates of travel of salmon bound in different directions and the rates of 
those bound in the same direction in different portions of the run. It might be 
anticipated that the rate of travel would bear a definite relation to the exigencies 
of the case, causing laggards in leaving the feeding grounds to accelerate their pace 
in comparison with the migrants of the early part of the season. 
METHOD OF TAGGING 
The tags used are of a common commercial type intended originally for tagging 
sheep and cattle. Each consists of a flat strip of aluminum about 3 inches long, 
on one side of which is stamped a serial number and the initials “ U. S. B. F.” Close 
to one end a hole is cut, and the other end is flattened and sharpened into a sort of 
prong. The tag is then bent, as illustrated by the open tag held in the tongs in 
Figure 2. The photograph also shows the character of the tongs by which the tags 
are attached. A spring within the handles of the tongs keeps them wide open 
except when closed by the hand of the operator. This tool is so made that the 
tag snaps into place and is held by the elasticity of the tag itself, which is opened 
slightly wider than the tongs when fully extended. As the tongs are closed, the 
prong or sharpened end of the tag passes through the hole on the other end and is 
crimped back securely against the body of the tag. This is well illustrated by the 
views of the closed tag (fig. 2). 
The tags were attached to the upper lobe of the caudal fin of the salmon. An 
attempt was made, and nearly always successfully, to insert the prong through the 
skin which extends back over the bases of the rays of the caudal fin. This is illus- 
