CHAPTER IV 
THE SCALES OF THE SALMON AS RECORDS 
OF THE SALMON’S LIFE 
Age of salmon to be told from their scales—Progressive 
growth of the scales—Lines of growth on scales—The 
spawning mark—Records of marked smolts as shown on scales 
—Records of small spring fish marked as smolts—Infrequency 
of the spawning mark—Scales of kelt recaptured as clean 
fish—The average number of lines added—Scales of large 
salmon—Salmon disease—The bacillus of origin—Fungus 
spreads quickly on dead fish 
Durine the last three years or so we have been 
gradually and with increasing certainty realising 
that a study of the scales of the salmon yields a 
most valuable addition to our knowledge of the 
fish’s life. 
We have long been able to tell the age of a horse 
by looking at its teeth. In like manner we can now 
tell the age of a salmon by looking at its scales. 
Other hard tissues, such as the bones, would no 
doubt show corresponding information—the ear 
bones or otoliths have already been used for the 
purpose with regard to many species—but in the 
case of the salmon a properly selected scale is by 
far the most convenient tablet to consult and is at 
the same time a very satisfactory one. 
