THE BREEDING HABITS OF SALMON AND TROUT 



By Leonard P. Schultz 

 Assistant Curator, Division of Fishes, United States National Museum 



[With 5 plates] 



Although salmon and trout are of the greatest economic importance 

 in the Northern Hemisphere and have been introduced into scattered 

 areas south of the Equator, authentic information concerning their 

 breeding activities is not generally available. Many volumes have 

 been written on the life histories of salmon and trout, including 

 several popular books, nearly all of which incorrectly portray the 

 spa-wTiing habits of this great group of fish belonging to the family 

 Salmonidae. The technical selection and breeding of domestic 

 animals, such as cows, horses, pigs, and chickens, is a highly specialized 

 science now, but the selection and development of similar brood stocks 

 of trout received little attention until recently. 



The spawning migration of salmon is anadromous, or from the sea 

 to fresh-water streams. This is the reverse of that of fresh-water 

 eels, Anguilla, which have a catadromous migration, or from fresh- 

 water streams to the sea. Those eels which live in the streams tribu- 

 tary to the region of the North Sea migrate westward in the North 

 Atlantic Ocean a distance of about 3,000 miles to a location a httle 

 north and east of the West Indies. This long migration is no greater 

 a distance than the king salmon of the Pacific travels to deposit its 

 eggs. In the Yukon River some salmon go up the river 3,000 miles 

 (Gilbert, Bull. U. S. Bur. Fish., vol. 38, p. 318, 1921-22 (1923)), in 

 addition to a long migration while still in the sea. The migration of 

 the king salmon is probably the longest of all salmon and trout; the 

 pink salmon migrates least of all of the Pacific salmon (genus Onco- 

 rhynchus), since it spawns near the mouths of streams or upstream but 

 a few miles above salt water. 



In trout, genera Salmo and Salvelinus, the migratory instinct is 

 also definitely developed, but these forms spend most or all of their 

 lives in fresh water and thus there is no necessity of migrating so far. 

 Other closely related famiUes of salmonidlike fishes, such as white- 

 fishes (family Coregonidae) and smelt (family Osmeridae), make 



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