120 THE NEW AKT OF BREEDING FISH. 



always returns after its annual, sometimes bi-annual 

 migrations to sea, to the rivers in which it was bred, 

 provided it escape during its immigrating voyage 

 through salt water, destruction by fish of prey, am- 

 phibious animals, or by the devices of man. 



It does not return from the sea to fresh water for 

 the proximate or immediate purpose of spawning. 

 If it did, we should not have fresh-run fish in Janu- 

 ary, February, and March. " Few salmon breed be- 

 fore October. The general breeding time is the lat- 

 ter end of November and the beginning of December. 

 Salmon emigrating from the sea in the first months 

 of the year will occasionally make a second sea voy- 

 age in the summer, and return in the autumn to 

 their native rivers. When salmon are surfeited with 

 sea-found food, and have become full-fed and fat, 

 they grow tired of salt water and its feeding grounds, 

 and make for the estuaries and rivers. If the salt 

 or brackish waters of the former are not well tinged 

 with fresh water, the salmon remains in them until 

 there be a flood in the rivers. They know when this 

 takes place by the increased quantity of fresh water 

 rushing into the narrow firths. Fresh water being 

 lighter than salt water, it flows above the latter, and 

 up into it the salmon swim, gambolling and swim- 

 ming rapidly for the swollen river, its state enablingi 

 them to surmount weirs, cruives, and other obstacles, 

 which would obstruct their passage if the river was 

 low. In dry summer weather very few salmon are 

 found in the rivers. A flood comes, subsides in two. 



