PROGRESS IN BIOLOGICAL INQUIRIES, 1939 81 
a short closed section (less than one-half mile) protects the large fish. 
Evidently they did not exhibit much movement during the summer. 
Shasta Dam. studies—Surveys to determine the ‘most, feasible 
means of salvaging chinook salmon whose migration will be blocked 
by the Shasta Dam were continued on funds provided by the Bureau 
of Reclamation. These surveys showed that none of the tributaries 
of the Sacramento River below the dam site afford either spawning 
areas or suitable water for transference of the salmon. 
In order to provide a suitable stream to which the salmon runs 
‘an be transferred, it is proposed to bring water by flume from the 
McCloud River to Stillwater Creek, and thus provide a permanent 
flow into this stream. Stillwater Creek rises in the foothills on the 
southern edge of the future reservoir and flows south about 24 miles 
to join the “Sacramento River south of Redding. At present this 
stream has an intermittent flow and is dry during part of the sum- 
mer and fall. Nevertheless, chinook salmon spawn in it naturally, 
and its gravel bed should provide excellent spawning grounds if a 
permanent flow is provided. The plan also includes a hatchery, with 
holding and rearing ponds, at the head of Stillwater Creek. 
Counts of adult salmon that passed over the dam at Redding were 
continued during 1939. Between April 17 and December 9 a total 
of 21,897 chinook salmon were recorded. These counts do not include 
fish that ran in late fall, winter, or early spring, and it is estimated 
that the total run now passing the site of Shasta Dam is approxi- 
mately 25,000 fish. A preliminary report on the entire Shasta Dam 
salvage problem is In preparation and will be completed early 
in 1940. 
PARASITES AND DISEASES OF FISH 
Increased facilities for pathological work at Seattle, Wash., have 
enabled Dr. Frederic F. Fish to carry on his nae to much better 
advantage. His most important contribution during 1939 was the 
discovery that formalin is a most effective agent for the control of 
the external parasites of fish. In the formalin treatment, fish-cultur- 
ists now have at their disposal a safe, practical, and economical 
method of eliminating ectoparasitic protozoans, and possibly other 
parasites as well. Heretofore the great limitation to prolonged treat- 
ments has been the lack of a disinfectant possessing a sufficiently 
Jarge factor of safety between effective and lethal concentrations. 
Comparative tests with a protozoan parasite (7richodina sp.) showed 
conclusively that formalin was far more effective than any other 
disinfectant used. Exposure of heavily infected fish to a 1:4,000 
solution of formalin for 60 minutes resulted in complete elimination 
of the parasite, without injury to the fish. 
However, prolonged treatments in the standing water of a fish 
pond, although simple, effective, and cheap, involves oxygen deple- 
tion and the accumulation of carbon dioxide. A comprehensive 
investigation of this problem is now under way, the ultimate objec- 
tive being the preparation of a series of tables giving the time re- 
quired to exhaust the dissolved oxygen to an arbitrary level of 4 
p. p.m. under all normal hatchery conditions. 
A second major investigation was the study of an epidemic of 
Costia necatriv at the Bureau’s hatchery at Birdsview, Wash., in 
