242 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



temperature. If the air and water circulations are not used it is neces- 

 sary to aerate the water with a dipper, that is, to take a dipperful of 

 water from the can and, holding- it up about 2 feet, pour it back, thus 

 taking air with the water to the bottom of the can. This is done as 

 often as is necessary to keep the water fresh. 



Whitefish fry are carried in water at a temperature from 33^ to 45° F. 

 If necessary to reduce the temperature, ice can be placed in the water 

 with the fry. If the air and water circulations are used, about 40,000 

 fry can be carried in each can. Without the circulation 20,000 are 

 carried, and in order to aerate them it is necessary to draw off in a pail, 

 through a screened siphon, about one-half the water in the can. This 

 is then thoroughly aerated in the pail with a dipper and returned to 

 the can, with a small amount of fresh water added. When a car arrives 

 at its destination, the cans are taken to a tugboat or steamer and 

 carried to the spawning-grounds where the whitefish are to be planted, 

 by carefully lowering the cans into the water and allowing the fry to 

 escape. On board the boat they are given fresh water as fast as is 

 required to keep them alive. 



Shad fry are carried in water at a temperature of from 55° to 65°, 

 depending on the temperature of the water in which they were 

 hatched. These fry can not be carried successfully with the circu- 

 lating system of water or air, and aeration, by the use of the dipper, is 

 therefore necessary. From 20,000 to 30,000 are carried in eacb can. 

 When the water is to be changed, it is drawn off through a siphon into 

 a pail, the head of the siphon beiug in a wire cage, covered with 

 cheese-cloth to prevent the fry from escaping. After the water in 

 the pail has been thoroughly aerated and ice added to bring the tem- 

 perature down to what is required, it is poured back through a large 

 funnel which reaches nearly to the bottom of the can. To prevent the 

 force of the water from injuring the delicate fry, the lower part of the 

 funnel for about 6 inches is made of perforated tin. When long trips 

 are made, the sediment which collects on the bottom of the cans is 

 removed, as soon as it is noticed, by drawing it off through a siphon into 

 a pail. Should any fry come out with it, they are carefully returned 

 to the can by dipping them out after the sediment has settled to the 

 bottom of the pail. If a trip lasts five or six days, the cans are cleaned 

 every other day by transferring the fry with a dipper from one can to 

 the other and cleaning the empty one before the fry are returned to it. 

 Shad fry are more tender than any other young fish moved on the cars, 

 and the greatest care is necessary in handling them. 



Trout and salmon fry are carried in water at a temperature of 36° to 

 46°, though rainbow trout are sometimes transported in water 10° or 

 15° warmer. If it is necessary to reduce the temperature, ice is placed 

 in the cans with the fish. Each can contains 5,000 trout fry, and 2,000 

 to 3,000 salmon fry, when the air and water circulations are used; 

 without air circulation, 3,000 or 4,000 trout, and 1,200 to 1,500 salmon 



