8 U. S. BUREAU OF FISHERIES. 



Remarkable results have been attained in introducing this fish 

 into new waters in many sections of the country and in foreign lands, 

 one of the most noteworthy instances being in connection with the 

 Au Sable River in Michigan. This stream originally was the home 

 of the grayling, a spring spawner. The utilization of the river by 

 the lumber interests for the passage of logs at the time of the year 

 when the grayling were spawning resulted in the destruction of the 

 spawning beds and the consequent gradual disappearance of that 

 species. The brook trout was suggested as the proper substitute be- 

 cause its spawning season is in the fall when the river is undisturbed. 

 The work of stocking this river with brook trout was undertaken by 

 the Michigan Fish Conmiission in 1885, during which year 20,000 

 fry were planted. This plant was followed from time to time by 

 others, and the outcome of the attempt was so successful that during 

 the spawning season of 1895 about 10,000 trout were captured on 

 the spawning beds by means of a small seine and their eggs taken for 

 artificial propagation. Many other Michigan streams where this 

 fish was not indigenous have since been successfully stocked. 



The most remarkable results of this work of acclimatization have 

 been attained in the Black Hills and the Rocky Mountains. In these 

 regions beautiful lakes and rivers hundreds of miles in extent, which 

 formerly were either devoid of fish life or inhabited by coarse species 

 of little value have been stocked so successfully with brook trout by 

 the Bureau of Fisheries that they now constitute its chief source of 

 supply for collections of wild eggs of that species. 



In its native haunts, whether in lake or stream, the brook trout is 

 always found in clear, cold spring water when it is accessible. When 

 freshets occur, it pushes from lakes or rivers into the spring brooks 

 of the upper waters, seeking out deep pools and eddies where it can 

 lie concealed beneath the shelter of grassy banks or accumulations of 

 drift and see without being seen. Throughout its range the brook 

 trout spawns in autumn during the falling of the water temperature, 

 the season beginning earlier in the north than in southern latitudes. 

 In the Colorado region the first eggs are deposited in September and 

 sometimes in August, while in New York and New England the sea- 

 son usually begins about the middle of October. Generally speak- 

 ing, the spawning period does not last more than three or four weelis, 

 though in some parts of the country, where the fish live in a copious 

 flow of spring water subject to little change of temperature, it may 

 cover three months or more. 



As the spawning time approaches the fish seek suitable gravel beds 

 for the deposition of their eggs. Those inhabiting lakes and ponds 

 may find suitable nesting spots in those waters, or they may enter 

 tributary streams, sometimes pushing long distances up to their head- 

 waters. A favored nesting locality in a stream is at the head or the 

 foot of a large pool, where the water ripples gently over gravel bars. 

 The males usually precede the females, and they frequently have the 

 beds well cleaned before the latter appear. The nests are formed 

 by working out little depressions in the gravel and scrupulously clear- 

 ing them of all sediment. In lakes or ponds such nests are made on 

 gravelly shoals or bars where seeping water is present, either in the 

 form of springs entering the pond or lakes or water seeping from the 

 pond through a porous section of its bottom. 



