PROPAGATIOlSr 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 ISO. 



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 

 liiUcheiy,. with ll.(XH) fiy to a tray and 4 trays in each basket cnnipartment, 

 making atotal 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 eliminate<l, 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 fiehl 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 P'ish and (Jame 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-efjuipped hatchery, located in 

 the lower section of the l)ay. the bureau woidd be in a position to save 

 the immense numbers of eggs — estimated to l)e over a i)illion a year — 

 wliicb are now i)eing sent to market in the fish and lost. 



At the pike-perch substation located near the head of Lake Cham- 

 plain, at Swanton, Vt., large numbers of pike-perch eggs aie lost 

 every spring because of inadequate facilities. Before any appre- 

 ciable improvement can be expected at this station it will be neces- 

 sary tf) provide an efficient penning system, so that the large numbers 

 of i)artially ripe fish taken by commercial fishermen may be held 

 tinder favorable conditions awaiting the full development of tlieir 

 eggs. 



So far as the propagation of whitefi.sh, 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 



100207'— 22 3 



