Fish Culture in Inland Waters 293 



and averaged 56.6 degrees. The weather conditions were clear and 

 warm on the first two days and on the last day clear and very hot. 

 Trout were common in this brook. 



Another considerable tributary joins Quaker Run just below 

 the wooded section of the stream, the lower limit of the season's 

 observations (figures 40, 41}. Trout were common in this brook, 

 particularly well up the stream. The temperature ranged from 64 

 to 67 and averaged 65.5 plus, on August 16 and 18, from 10:30 a.m. 

 to 4 130 p.m. The Aveather conditions were clear and hot. 



In connection with a large, rather open pool in the woods, which 

 contained trout, the following temperature observations were made : 

 Air in the shade 81°, in sun 91° ; running water in shade immedi- 

 ately above the pool, 64.5° ; in the pool immediately below, 65.5" ; 

 running water immediately below the pool in shade, 65.5°. 



August 17 was a clear, very hot day. On that date a section of 

 brook tributary to Red House Creek was examined. In the upper 

 section of the brook, which was in the rather heavily wooded hills, 

 the temperature of the air in the shade was almost uniformly 75 

 degrees. The temperature of the brook was uniformly 59 degrees 

 excepting near an inflowing spring where it was 58 degrees. Emerg- 

 ing from the woods into an open country, a small shallow pool 

 was observed which contained one trout 7 or 8 inches in length. The 

 temperature of the air in the shade here was 80 degrees and that 

 of the water 74 degrees. Seventy yards further along in the open 

 country was a pool under a shelving ledge where a number of fair 

 sized trout were glimpsed as they disappeared under the shelf. The 

 temperature of the air here was still 80 degrees in the shade, and 

 that of the water was 75 degrees. Not far below the brook joined 

 Red House Creek, where the air registered 92 degrees and the 

 water in an open jX)ol 85 degrees. 



In connection with the 75 degrees set by Embody as a dividing 

 point this is interesting, as it shows a rather sudden transition from 

 " cold " to " warm " water, and that the intermediate section was 

 occupied by trout only at its upper end, although apparently in 75 

 degrees of water temperature. It was impossible, however, to 

 determine the temperature under the shelf. The open brook below 

 contained multitudes of black-nosed dace, very few of which were 

 found above the open tract. Red House Creek was " alive " with 

 cyprinids of several species, suckers, and small blackbass. 



If the limited temperature observations of the Allegany Park 

 trout streams could be regarded as significant of anything con- 

 cerning brook trout they would indicate that the optimum conditions 

 are in waters not warmer than 60 degrees, and that 75 degrees repre- 

 sents the limit of even temporary endurance. However, the present 

 writer makes no claim that they are sufficient for such a deduction. 

 But given a stream the temperature of which does not exceed 60 

 degrees in the hot season, other things being favorable, no one need 

 hesitate to plant brook trout in them. If the higher degrees are 

 observed, other conditions such as possible hotter and dryer seasons 

 must be considered also. 



