to sea, to distant feeding grounds. Per¬ 
haps they stay close to shore. 
And then, when they have reached 
their greatest beauty and strength, they 
are stirred by the call to return to the 
spawning grounds. 
Men have made a great effort to find 
out how old the salmon are when they 
spawn. They know now that the age is 
different for each kind. Some spawn 
when they are two years old. Others 
wait until the sixth or seventh years. 
This was discovered in a very interest¬ 
ing way. Men noticed that the scales of 
the fish had rings, just as the inside of 
a tree does, and they studied these rings. 
They found that every year more rings 
are formed on each scale. In the summer 
wide rings are formed. The rings that 
grow in winter are narrower. For every 
year each scale has a set of wide and 
narrow rings. By counting the rings on 
scales of salmon caught just after they 
30 
