PROPAGATION AND DISTRIBUTION OF FOOD FISHES, 1921. 31 
partment of the hatching trough and held thus from March 12 until the yolk 
sac had been completely absorbed, on June 7. The total loss of fry during this 
period was 180. . 
Without the trays only about 50,000 salmon fry can be safely 
carried in a standard 16-foot hatching trough through the sac stage. 
It would therefore appear that by the use of this system the fry 
capacity of each trough is increased by approximately 200 per cent. 
J. R. Russell, superintendent of the Baker Lake station and its 
auxiliaries, in the State of Washington, writes: 
The stacked tray system for holding fry during the sac stage was tested 
this year for the first time, 1,000 of the trays being in use at the Baker Lake 
hatchery, with 11,000 fry to a tray and 4 trays in each basket compartment, 
making a total of 264,000 fry per trough. The system proved an entire success. 
The loss was small. The danger from smothering, which sometimes occurs 
when large numbers of fry are held on the trough bottoms, appeared to be 
entirely eliminated, and the ‘‘ paddling” of the fry, which is essential in the 
trough, is rendered unnecessary. 
From this statement the trough capacity appears to be even greater 
than was indicated by the experiment at the Yes Bay station. Dur- 
ing a period of water scarcity at the Baird (Calif.) station the trays 
were successfully used to economize in space and water. 
PROPAGATION OF FISHES OF THE GREAT LAKES. 
The bureau’s work in the propagation of the commercial species 
indigenous to the Great Lakes extends from the Rainy Lake region, 
in Minnesota, to Lake Champlain, in Vermont. Under existing 
conditions the work in this field fails of its fullest efficiency through 
a lack of adequate facilities. An example of this condition is sug- 
gested in the possibilities that exist in the propagation of pike perch. 
In the Rainy Lake field, where pike-perch propagation has been 
tried in a tentative way, arrangements may be concluded with the 
Minnesota Fish and Game Commission for. the establishment of a 
small inexpensive hatchery, to be operated jointly by the bureau and 
the State as an adjunct of the Mississippi Valley work. 
Another important pike-perch field awaiting development is in 
Saginaw Bay, Mich., this region offering greater returns for a given 
expenditure of funds than any other of which the bureau has knowl- 
edge. With an inexpensive but well-equipped hatchery, located in 
the lower section of the bay, the bureau would be in a position to save 
the immense numbers of eggs—estimated to be over a billion a year— 
which are now being sent to market in the fish and lost. 
At the pike-perch substation located neat the head of Lake Cham- 
plain, at Swanton, Vt., large numbers of pike-perch eggs are lost 
every spring because of inadequate facilities. Before any appre- 
ciable improvement can be expected at this station it will be neces- 
sary to provide an efficient penning system, so that the large numbers 
of partially ripe fish taken by commercial fishermen may be held 
under favorable conditions awaiting the full development of their 
eggs. 
So far as the propagation of whitefish, lake trout, and cisco (lake 
herring) is concerned, there has been no notable change in recent 
years either in methods pursued or the fields occupied. Probably 
the greatest improvement in this branch of the work, both as regards 
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