98 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



After the incubation has reached a stage where the fish are begin- 

 ning to break their shells, the hatching-box is taken out and reversed, 

 the open end being fixed snugly against the lower wall of the compart- 

 ment. The closed end of the box being thus placed upstream, the 

 water is prevented from entering except through its former exit, the 

 holes in the bottom of the box, and is thus forced up through the box, 

 with an exit at the toj) which prevents the sacs of the hatching fish 

 from being forced, by pressure from above, down through the screen, 

 as would be the case if the box were left in its former position. 



When the process of hatching is nearly completed the trays are 

 removed and emptied into a large pan filled with water, where the dead 

 shells and other refuse, being of low specific gravity, rise to the top 

 and can be easily poured ofl". This is called washing the fish. The fish 

 are then replaced upon the trays and returned to the hatching-boxes, 

 where they remain until the food-sac is nearly absorbed, a period of from 

 25 to 40 days, according as the temperature varies from 50° to 38"^ F. 



The young fry, deprived of their food supply by the absorption of 

 this sac, must soon be placed where they can get their sustenance else- 

 where. They may be planted in waters suitable to their nature, or 

 reared for breeding or other purposes at the station. 



PLANTING THE FRY. 



In their natural state, as soon as the weight of the food-sac has 

 diminished by absorption enough to permit their rising, the fish begin 

 to take food, and by the time the sac is entirely gone they are probably 

 taking it regularly. When very young fry are transferred to outside 

 waters where there is natural food only, it should be done 8 or 10 days 

 before the sac is entirely absorbed, for, if delayed till after the sac dis- 

 appears, many will die before they become accustomed to finding food 

 in their new home. 



Brook trout fry are usually transported in ordinary round-shouldered 

 cans of 10 gallons capacity, the number of fish per can depending 

 entirely upon the distance they are to be carried and the facilities for 

 taking care of them en route, such as opportunities for changing the 

 water, supplying fresh ice, etc. For a short trip of from 5 to 10 hours 

 duration, between 4,000 and 5,000 are carried in each can, but where 

 they are to be on the road from 1 to 5 days, it is hardly safe to attempt 

 carrying more than 2,500. The United States Fish Commission dis- 

 tributes fry by means of its cars, built especially for the purpose, in 

 which either running water is kept upon them or fresh air introduced 

 into the water to make it life-sustaining. Small shipments are made 

 by a special messenger in a baggage car, the railway companies usually 

 oifering every available opportunity for changing water, etc. The fish, 

 upon arrival at the railway point nearest their destination, are carried 

 thence by wagon to tlie stream where they are to be planted, by dis- 

 tributing thein in small lots in different places where there is shallow 

 water and a good bottom. 



