112 
BULLETIN OF THE BUREAU OF FISHERIES. 
The phytoplankton consisted of one desmid — Staurastrum — and two fila- 
mentous fo rms — Mougeotia and Zygnema. The Mougeotia, however, comprised 
the major portion of the limnetic plant life. The maximum number of algae per 
cubic meter of water was found between 60 and 100 m. The maximum number of 
Staurastrum per cubic meter of water was found between 60 and 80 m. This 
desmid was not found in the catches above 20 m. Below 80 m. the number of 
Staurastrum decreased very rapidly, and below 200 m. very few were found. 
DIURNAL MIGRATION. 
On July 23 some observations were made on the diurnal migration of the 
Crustacea in Lake Tahoe. Plankton catches were taken at 5 a. m., 10 a. m., 4 
p. m., and 9 p. m. (See Table 12, p. 133.) At 5 a. m. while it was cloudy and dark 
the maximum number of copepods per cubic meter of water was found in the 10-15 
m. stratum. It remained dark and cloudy all morning, and it was raining at 10 
a. m. when the second catch was made. At that time there was a somewhat smaller 
number of copepods in the 0-5 m. stratum, but the maximum number ner cubic 
meter of water was still between 10 and 15 m. 
About noon the sun came out and shone brightly during the afternoon. A third 
set of catches was made about 4 p. m., which showed a relatively larger number of 
copepods in the 0-5 m. stratum, with the maximum number per cubic meter of 
water between 5 and 10 m. With the decreasing amount of sunlight toward even- 
ing, the copepods began to move toward the surface, for 21.8 per cent of the number 
was found in the 5-10 m. stratum. At 9 p. m. the catch showed the maximum 
number per cubic meter of water to be in the 0-5 m. stratum. About 41 per cent of 
the copepods were in this layer of the lake, showing a decided upward migration. 
The maximum number of nauplii per cubic meter of water was found in the 
0-5 m. stratum in every catch. Apparently they showed no diurnal movement. 
UPPER KLAMATH LAKE, OREG. 
The upper lake lies north of the city of Klamath Falls. Its greatest length is 
nearly 56. km. (35 miles), and its width varies from 4 (2.5 miles) to 20 km. (12.5 
miles). Most of the lake is very shallow. The launches stir up the bottom mud 
for the greater part of the trip up the lake, although they travel in the deepest water 
to be found. The deepest place is near Eagle Ridge, where an area of several square 
kilometers has a depth of 8 m. In the channel between the south end of Bear 
Island and the shore we found 1 1 m. of water over a small area. 
The lake is noted for its rainbow trout ( Salmo irideus) fishing, which, consider- 
ing the very warm water (see p. 120) and the abundant growth of algae, appeared 
interesting. Two trout that weighed from 4 to 5 pounds each were caught near 
Eagle Ridge. They took a small spoon readily (they would not take a fly, but were 
reported as doing so earlier in the season) and fought well. The flesh seemed 
hard and firm, but when cooked it had a very marked weedy taste similar to the 
trout from Henry Lake, Idaho. The best fishing was reported at the mouth of 
the streams where the colder water occurred. 
