VARIATION IN DEPTH AT WHICH FISH CAN LIVE 
5 
a young bullhead, a young smallmouth black bass, and three 2-year-old perch was 
placed at 47 J feet. A cage with similar contents was placed at 50 feet. At 11.20 
a. m. the fish at 45 feet were in good condition. At 47^ feet the bass and one 
perch were dead but the others seemed to be in good condition. At 50 feet all the 
fish were dead. At 3.30 p. m. all of the fish at 47| feet were dead and those at 45 
feet were in good condition. At 6.40 p. m. those at 45 feet were still all right, and 
in the cage at 47J feet were placed young perch, j^oung Lepomis gibbosus, and 
young rock bass. At 7.30 a. m. of the following day all of the fish at 47^ feet were 
dead, and in the cage at 45 feet a young bass and two perch were still living, but the 
others were dead. The fish of that cage had been confined at that depth for three 
days. The lowest limit at which fish could live was very definitely between 45 and 
47^ feet, and in the upper portion of the thermocline. 
The last test of the season at Station A showed a still further depression of the 
thermocline and a corresponding change in the depth at which fish could live. 
August 22, 1921, Station A 
Depth 
45 feet 
47i feet 
50 feet 
55 feet 
70 feet 
Temperature, °F 
64.4 
4.84 
8.4 
64 
3. 70 
8.0 
61 
2. 35 
7. 3 
51.4 
48.8 
0 
6.8 
Oxygen, c. c. per liter 
PH 
At 1.05 p. m. fish were placed at 45, 47^, and 50 feet, as follows: A cage placed 
at 45 feet contained 7 young perch, 1 yearling sucker, 2 yearling rock bass, and 2 
yoimg bullheads. A cage placed at 47^ feet contained 5 young perch, a half-grown 
sucker, a young Lepomis gibbosus, 2 minnows, and 3 young bullheads. A cage 
placed at 50 feet contained 2 young perch and 3 young bullheads. The perch used 
were mostly 2-year-olds and the remainder were yearlings. At 3.15 p. m. the fish 
at 45 feet were all in good condition, and those at 47^ feet were also, except the two 
minnows, which were ailing. In the cage at 50 feet the perch were dead and the 
bullheads nearly dead. At 7.05 p. m. the fish at 45 feet were in good condition and 
were transferred to Station B for a test to be described later. At 47^ feet the two 
minnows were dead and the L. gibbosus was ailing. These were discarded and the 
others, still in good condition, were transferred to Station B. The fish at 50 feet 
were all dead. The lowest limit at which fish could live at Station A was about 
7 feet deeper than on August 5, two and one-half weeks previous. 
As already stated, high winds and rough water made two of the three tests at 
Station B in 1921 quite unsatisfactory. The fish were necessarily confined in a 
relatively small "live box" in a rowboat for an horn* or more, while journeying to 
the station and while temperature and chemical records were being made. During 
all of this time they were being jostled about because of the motion of the boat, due 
to the rough water. After they were submerged, the cages containing them were 
being continually jerked about because of the action of the waves on the float from 
which the cages were suspended. Although unsatisfactory, the records are not 
without significance. 
