88 
bulletin of the bureau of fisheries. 
HENRY LAKE, IDAHO. 
Henry Lake, Idaho, lies 29 km. (18 miles) west of Yellowstone, Mont., from 
which place it may be reached by stage or auto. It occupies the center of a mountain 
marsh. The lake is 9.6 km. (6 miles) long by 5.5 km. (3.4 miles) wide. It was 
reported as a deep lake, but careful sounding gave a maximum depth of 2 m. (6.5 
feet), and most of the lake has a depth of 1.5 m. (4.8 feet). It has an elevation of 
1,961 m. (6,433 feet), which, with the large amount of snow on the surrounding 
mountains, makes the summer season very short. The air temperature reached the 
freezing point on the night of August 11, 1912. This may explain the abundance of 
cutthroat trout ( Salmo clarTcii) in the warm water. They took the fly readily and 
fought well. Jordan and Evermann state that the Mackinaw trout ( Cristivomer 
namaycush ) is known from Henry Lake in Idaho. (See page 112 of this report and 
compare with Upper Klamath Lake, Oreg.) 
In Henry Lake both Crustacea and algae were abundant. The Crustacea, 83 
per cent of which were Diaphanosoma leuchtenbergianum, numbered 9,970 per cubic 
meter of water, and the nauplii 990. Amphipods were present in very large numbers. 
The algae consisted of Microcystis and Asterionella. The maximum number of the 
former per cubic meter of water was 19,800; of the latter, 39,600. 
If lakes were to be ranked for fish production in accordance with the amount 
of plankton, the shallow lakes would have to be considered vastly more valuable 
than the deeper ones. It must be remembered, however, that it is the animal 
portion of the plankton, rather than the algae, that directly furnishes the food for 
fish. Henry Lake seemed to be well stocked with trout (Salmo clarkii), but the 
water was so warm (63.2° F. or 17.3° C.) that the flesh of the trout had a poor 
flavor. Many of the trout were found in the creeks that flowed into the lake, but 
even the creeks were too warm for good, healthy trout. 
LIBERTY LAKE, WASH. 
This is also one of the very shallow lakes with marshy places on two sides. 
The lake was just in the "bloom” stage of its history at the time of our visit. The 
algae were so very thick that the other representatives of the plankton were counted 
with difficulty. 
The Cladocera were reproducing rapidly, the brood chambers of adult females 
showing many eggs in various stages of development. 
LOON LAKE, WASH. 
Loon Lake is about 32 m. (104.9 feet) deep and has a marshy place at the 
upper end where a small stream flows into it. The water is very clear; the disk 
was read at 8.5 m. For the most part the shore is gravel or fine, clean sand, which 
adds greatly to its clearness. 
Algse were scarce in the net plankton of this lake. They were most abundant 
in the region of the thermocline. Copepods and nauplii were also most abundant 
in this stratum. 
