Robertson. — Hatching Fry in Gravel 151 



as when buried four months before, while eggs spawned the same 

 day and fertilized, had hatched. I put this lesson into practise 

 at Cultus Lake Sub-Hatchery, which is under my charge, in 1916 

 and 1917. The troughs there are within two hundred feet of the 

 fish traps and consequently it is an easy matter to place the eggs 

 in the baskets before they harden. When this was done no 

 picking was necessary, and the eggs were not disturbed until 

 they were well eyed and then only because the accumulation of 

 silt, etc., compelled shaking up, which, of course, ended the 

 existence of the infertile eggs. I did the same thing with hump- 

 back eggs at Harrison Lake; put them in the baskets soft, never 

 disturbed them till well eyed, and then separated them in brine. 



DEPOSITING THE EGGS IN HATCHERIES. 



In any instructions I ever read regarding the handling of eggs, 

 no mention is made of the desirability of getting the eggs into 

 the baskets before they harden. On the contrary the method 

 usually advocated is to allow them to harden before they are put 

 into the trays in which they are to be transported, and some 

 hatcherymen even allow them to harden in the milt. 



If the eggs are taken at a distance from the hatchery it is 

 impossible to follow the method I advocate, and the best results 

 need not be expected. 



At Cultus Lake the spawning pans, holding five quarts, were 

 filled, carried to the troughs and emptied into the baskets, where 

 they were washed. Thus two operations sufficed instead of the 

 customary five, namely, spawning pan, washing pan, measure, 

 tray and basket, and in addition no first picking was necessary. 



The transportation of eggs, especially those not eyed, is inimical 

 to the production of strong fry, for though it may not actually 

 kill, it has a weakening effect. 



GRAVEL HATCHED FRY. 



Assuming that the fry have hatched successfully in the gravel, 

 in spite of the drawbacks enumerated, we find that the fry stay in 

 the gravel until the sac is absorbed, and longer under certain 

 conditions which at present are unknown. 



It may depend on the food supply, on season, or on the tem- 

 perature of the water, but I am convinced that the time of 



