26 REPORT OP COMMISSIONER OF FISH AND FISHERIES. 



percentage of loss can uot be given ; but the total loss of alevins at 

 the hatchery the past season was 32,934, or 0.3 per cent, in a total of 

 10,000,000. The loss after feeding began was very slight, amounting 

 only to 5,710. 



The alevins and the fry of the Pacific salmon possess great vitality 

 and are less liable to disease than those of any of the other Salmonidcv. 



The natural conditions for hatching, rearing, and planting fry at the 

 Sisson hatchery are excellent; the water supply is unlimited and is 

 very free from sediment, even during stormy weather, while it has an 

 equable temj)erature, averaging 52° for the year, seldom falling to 40° 

 or exceeding 60°. 



No part of the hatching-house work requires more attention or is of 

 such vital imi^ortance as the cleaning of the troughs. Up to the time 

 that the alevins begin to feed the troughs should be thoroughly cleaned 

 ouce every day by rubbiug them down with the hand covered with a 

 coarse crash mitten, and after they begin feeding the troughs require 

 much more attention. One hour after each meal the troughs should 

 be cleaned by passing a bunch of stiff feathers over the sides and 

 bottom, first removing the division and harbor plates and the plug at 

 the foot of the trough. 



