274 DAYS AND NIGHTS OF SALMON FISHING 



are harder to interpret than others, but as a rule 

 their story can be read with a low-powered micro- 

 scope (Xio) or even with a strong magnifying glass. 



One scale (p. 56) displays what is called a spawning 

 mark, a thick dark line which is very prominent 

 among the fine ones and which goes all round the 

 scale, not being confined to the protected portion. 

 The spawning line is caused by the fact that when a 

 salmon is in the river for spawning purposes growth 

 stops altogether and the outer edge of the scale 

 becomes frayed and worn owing to the general 

 wastage of tissues that is caused by the great strain 

 of long fasting and deposition of milt or ova. If 

 after spawning the fish survives and manages to get 

 back to the sea as a kelt, growth begins again and 

 the scales grow with the rest of the fish, new lines 

 being formed on their circumference to mark this 

 growth. But the spawning mark remains indelible 

 and is a permanent witness to the fact that the fish 

 has been to the redds at the end of its fourth year 

 of life. 



The study of salmon scales is extremely interest- 

 ing, and as has been said earlier is very important 

 economically. Those who wish to go into the 

 matter more deeply could not do better than get 

 Mr. J. Arthur Button's little book Salmon Scale 

 Examination and its Practical Utility (1910) which 

 is an excellent survey of the subject. Various 

 interesting and instructive papers are to be found 

 in the literature issued by the Scottish Fishery Board 

 and in the Salmon and Trout Magazine, the quarterly 

 journal of the Salmon and Trout Association. 



