ARTIFICIAL PROPAGATION OF TROUT. 7 



the second year, many of the commercial breeders hold their fish 

 through the first spawning period only and are able to dispose of 

 both the eggs and parent fish at a profit. 



RANGE AND SPAWNING SEASON . 



The natural range of the brook trout in the United States is in 

 the eastern section of the countr}'. In Canada it occurs in mam' 

 streams and tributary waters of the Great Lakes, the St. Lawrence 

 River, and the Gulf of St. Lawrence, at least as far north as Hamil- 

 ton Inlet on the Labrador coast. Its northern limit is not def- 

 initely known, but it extends southward in the Alleghenies to head- 

 waters of streams in the mountains of Georgia and Alabama. It 

 was also found naturally originally in the Great Lakes region of the 

 United States a:- far west as Minnesota. 



Owing to its hardy nature and ability to adapt itself to new 

 surroundings, the species may be successfully transplanted into suit- 

 able streams, and it has become established in nonindigenous waters 

 in Michigan, Wisconsin, Minnesota, many of the waters of the Rocky 

 Mountains and the Pacific coast, in the Eastern States, and in creeks 

 and rivers of the Allegheny Mountains. With the possible excep- 

 tion of the rainbow trout and steelhead it is the hardiest member 

 of the salmon family and will make a brave struggle for existence 

 even with adverse surroundings. 



All streams can not be successfully stocked with this species. The 

 flow must not be too sluggish nor the temperature of the water 

 too high, although an unfavorable temperature, if not excessively 

 high, is no serious obstacle where the current is swift enough to 

 insure thorough aeration of the water or where the fish can run 

 into spring-fed creeks flowing into the main stream. The ideal brook- 

 trout stream receives numerous spring-fed tributaries throughout its 

 course, so that its temperature does not exceed 65° F. in summer 

 and by the same means is maintained at a relatively high tempera- 

 ture during the winter months. It has stretches of gravelly bottom, 

 clear, shallow water, and a steady current. It should also contain 

 large bowlders or projecting points of land at intervals for the 

 formation of quiet eddies and deep pools. 



Any stream having a summer temperature greater than 65° can 

 hardly be considered suitable for brook trout unless it has large 

 spring tributaries accessible to the fish during the heated period. 

 Through the cutting away of the forests and the cultivation of the 

 land many streams in the eastern part of the United States have be- 

 come unsuited to brook trout. Wash from cultivated land during 

 periods of heav}^ rainfall roils the streams and destroys much of the 

 natural food contained in them. The rainfall on cultivated slopes 

 drains rapidly into the adjacent streams, causing alternate periods of 

 freshets, with turbid water, and drought. In wooded or uncultivated 

 sections the rainfall is retained by the soil and returns to the streams 

 in a uniform flow of cool, sparkling spring water, extending through 

 periods of little rainfall. Streams flowing through open or cultivated 

 areas are subject to high summer temperatures, influenced by the 

 direct raj'S of the sun, and evaporation is increased proportionately. 

 It may therefore be said that the best trout streams are to be found 

 in wooded, hilly, or mountainous sections. 



