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 



During 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 corresjDonding 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. 



