THE PRINCIPAL TROUTS 



.'ainbow, brown, cutthroat, and brook 

 outs provide most of the sport fishing for 

 rout in the United States. 



Rainbow and cutthroat (blackspotted) 

 Lrouts are native to the western United States. 

 Rainbow trout have been distributed through- 

 out this country and others. Some of either 

 species may migrate from streams to the 

 ocean or large lakes and return to the streams 

 to spawn. The sea-run cutthroat is called 

 harvest trout ; the sea-run rainbow, steelhead. 

 Both species usually spawn in the spring of 

 the year when water temperatures are rising. 

 In hatcheries, domesticated rainbow brood 

 trout spawn in the fall or winter. 



The brook "trout" (actually a char) is na- 

 tive to the eastern United States but has been 

 distributed widely. Our widely distributed 

 brown trout were introduced from Europe. 

 Brook and brown trouts spawn in the fall of 

 the year when water temperatures are falling. 



Food supply and water temperature deter- 

 mine the rate of growth. Size of the female 

 determines the number of eggs deposited in 

 gravel. Trout spawn in the second or third 

 year and in each year of life thereafter. 



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NATURAL LIFE 



Trout eggs are deposited in prepared redds, 

 or nests in the gravel of stream beds — 



and hatch in 8 weeks or more. A young fish, 

 or fry, lives for 3 or 4 weeks on food absorbed 

 from the yolk sac. 



At about the time the yolk is completely 

 absorbed, the fingerling emerges from the 

 gravel and feeds on microscopic aquatic 

 organisms. 



From the many eggs deposited in the gravel, 

 only a very few young fish are produced and 

 survive to adulthood. Most of the eggs and 

 young fish die from natural causes, such as 

 floods, silt, drought, and predators. Under 

 natural conditions, relatively few trout reach 

 catchable size to be taken by fishermen. 



