64 The Salmon 
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, atten bein. one syearaand 
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 multi- 
plying the age of the fish—3,3, years— 
by 16, the number of rings which are 

added-each year) I heretake st Junie; 
| ________________________| because this was the date on which 
Fic. 57.—14 lbs. 4th May 1907. our first wired grilse was caught from 
ide those which were marked the year before. 
I give enlarged photographs (Figs. 57 to 63) taken each 
month from a scale from 
one of these wired erilse, 
which clearly show the 
increase in the number 
of rings as the season 
advances, a shave also 
made out —a table show= 
ing 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- 
Fic. 58.—23 lbs. 4th May 1906. North Esk. 
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 
