The brown trout acted in a normal manner until July 3, when 

 distress and loss of appetite occurred at a temperature of 84.2°. 

 They seemed to recover during the next two days with maximal 

 temperatures of 82.4° and 83.2°, respectively; but on July 6, 50 

 per cent of them died at 85.5°, and on the following day at 87° the 

 mortality was 100 per cent. 



The steelhead trout followed very closely the browns, with dis- 

 tress at 84.2°, 20 per cent mortality at 85.5°, and total mortality 

 at 87° F. 



The previous year, 1920, a similar experiment was tried, but 

 the highest water temperature recorded was 81.5° F. A few of 

 the brook trout were distressed and refused food, but recovered 

 completely during the next few days at maximal temperatures from 

 78° to 80°. The browns and steelheads were not disturbed by a tem- 

 perature of 81.5° and continued to eat normally throughout the 

 summer. 



It must be understood that the foregoing notes do not prove 

 that all strains of brook trout will stand temperatures of 80° F., and 

 above. Undoubtedly there is much variation in this respect just as 

 we find great variation in the rate of growth, in the behavior of trout 

 to current and light, and variation in power of resistance to disease 

 germs. 



Nor may we assume that brook trout will thrive in any pond 

 or stream whose temperatures do not exceed these uppermost limits. 

 Waters vary greatly in oxygen and carbon dioxide content, and these 

 gases may be present in insufficient amounts in one case or too great 

 amounts in the other to permit trout to live even in the low tem- 

 peratures of the average trout hatchery. 



So far as temperature alone is concerned, however, it is writer's 

 opinion that we have been a little too conservative and that we shall 

 have to revise to some extent our notions as to the meaning of 

 the terms, warm water and cold water. 



Discussion. 



Mb. J. W. TiTcoMB, Albany, N. Y. : Dr. Embody expressed the idea 

 very well when he said that the rainbow trout he got might have come up 

 from under the banks. But that was in trout streams, where the maximum 

 temperature existed a very short time in the middle of the afternoon, for 

 a day or a series of days. The trout can be seen in the shady pools when 

 the water is low and there is a high temperature. I think they instinc- 

 tively seek the shade and shelter of the banks where it is cooler than the 

 water of the stream, and they take care of themselves by leading a very 

 inactive life during these high temperatures. We cannot look upon such 

 temperatures as standards for the angler in applying for fish, because if 



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