The Salmon 



their silvery coat, continue to add rings to their scales just as those 

 in the sea do. 



I have never found a grilse in the Tay with a less number of rings 

 than fifty-one, showing clearly that smolts do not return the same 

 year as they go down. All the grilse that come up from June to 

 December spawn, and those that are long in fresh water have both 

 edges of the scales broken off, and by the time they go down as kelts 

 are very much impaired. 

 I have known as many as 

 six or eight rings become 

 detached, the upper edge 

 remaining as it was when 

 the fish came from the sea. 

 When the kelt grilse enters 

 the sea and begins to feed, 

 it at once forms a ring 

 round the broken part as 

 well as round the whole 

 part, and these rings in- 

 crease in number according 

 to the time the fish remains 

 in the sea. To find the 

 time the fish has spent 

 in the sea, then, we have 

 merely to count the number 

 of complete rings from the broken part outwards (Fig. 64). 



For example, a grilse of 7 Ibs. weight was caught in August 1906, 

 and its scales contained fifty-four rings. It spawned, and went dow r n 

 a kelt of 4 Ibs. on ist April 1907, and was caught again on i/th 

 August 1907, weighing 9 Ibs. The number of rings it had added from 

 ist April to i 7th August was seven, making the total number of rings 

 sixty-one. Its age, therefore, is four years and live months. Had it 

 remained in the sea a whole year, it would have added sixteen rings, 

 and would have weighed about 15 Ibs. In calculating the age from 



FIG. 64. 7 Ibs. 2Oth July 1907. 



