148 American Fisheries Society 



correct an impression that every gravel bar is a spawning bed and 

 accounts for the partiality shown by fish for certain localities. 



Seepage is not subject to the fluctuations in volume and 

 temperature prevailing in surface water and is cleaner and more 

 free from debris. 



WATER CIRCULATION IN THE TROUGHS. 



The circulation in hatchery troughs is indirect and is not 

 conducive to the production of strong fry. The eggs are in a 

 mass in the basket, which varies from one to two inches deep, 

 and the water, following the path of least resistance, passes to a 

 great extent under, over and by the sides of this mass. Even when 

 fifteen to twenty gallons of water per minute and riffle dams 

 are used, the eggs in the centre of a two inch mass are in a state of 

 semi-suffocation, and killing is only prevented by shaking up. 

 Eggs having all the appearances of suffocation may recover if 

 thinned out or shaken up, but the effect of this semi-suffocation 

 must be cumulative and must affect the strength of the resulting 

 fry. 



I spawned a number of eggs and placed a layer two inches deep 

 in a hatchery basket subject to the normal water supply and 

 riffle dams, and from the remainder I filled a whitefish jar full. 

 Just before the eggs hatched I counted the number of eggs to the 

 lineal metre several times from both basket and jar, and found 

 that the jar eggs were at least five per cent greater in diameter. 

 In the jar the circulation of water was direct ; in the basket indirect ; 

 and while this test may not be conclusive, a straw shows how 

 the wind blows and I intend going into it thoroughly this 

 winter. 



TEMPERATURE OF WATER IN THE GRAVEL. 



Seepage, according to the distance it has traversed the earth, 

 varies in temperature, ranging up to the temperature of so-called 

 spring water, which is about forty-five degrees, and varies very 

 little throughout the year. The temperature of water in the 

 streams from which the hatchery supply is taken very often 

 descends to thirty-four, and it is therefore quite obvious that 

 the natural incubating period may be half that of the hatcheries. 

 Some authorities are opposed to the use of spring water because 



