82 The Salmon 
water, z.e. from the time a clean fish enters fresh water until it returns 
to the sea. Some of them are a whole year in fresh water before 
spawning, and, as nearly as I can make out, lose twenty-five per cent 

Fic. 84.—14 lbs. 27th March. 
of their weight before and after this takes place; so that a fish of 20 
Ibs. leaving the sea on rst January 1907 is reduced to half that weight 
on its return as a kelt on rst January 1908. This percentage varies 
with the length of time the fish is in fresh water, and according to the 
river it frequents. 
