The Salmon 



F' r - 57- l Ibs. 4th May 1907. 

 North Esk. 



smolts until they return as grilse in May or June of the following 



year, or it may be two to six months 



later. If, then, a smolt returns on 



ist June, after being one year and 



two months in the sea, how many 



rings should it have on its scales ? 



On examining the scale we find there 



are fifty-one rings on it : the same 



result would have been got by mul- 

 tiplying the age of the fish- -3^ 



years by 16, the number of rings 



which are added each year. I here 



take ist June, because this was the 



date on which our first wired grilse 



was caught from those which were 



marked the year before. 



I give enlarged photo- 

 graphs (Figs. 57 to 63) of 

 scales from wired grilse, 

 taken each month, which 

 clearly show the number of 

 rings as the season advances. 

 I have also made out a table 

 showing the number of rings 

 on the scales at the different 

 ages. This table will be 

 found to be fairly accurate, 

 taking one month with 

 another. There may be a 

 difference of one or two 

 rings according to the feed- 

 ing in the sea being better 



in some months than others ; but if more rings than usual are 



added during any one month, the fewer are added in some of 



* 



FIG. 58. 2\ Ibs. 4th May 1906. North Esk. 



