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 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. 



