392 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



3. To avoid sudden changes of temperature in the cans containing the 

 fish. 



4. To avoid any agitation of the water in the cans. 



5. To furnish constant supplies of water containing minute natural 

 food. 



C. To guard vigilantly against the use of water in the least degree 

 unwholesome. 



Any failure to supply the above conditions will be immediately followed 

 by fatal results. 



Changes of water. — To make constant changes of water, experience 

 has shown to be one of the important secrets about keeping the young 

 fish in good condition. A change is usually made once in two hours. 

 Any temporary neglect of this precaution soon shows its effect in the 

 weakening of the fish, and prolonged neglect is fatal. 



A spare can containing a reserve of fresh water is usually carried along 

 with the other cans, and is filled as may be required at railroad-stations. 

 The changes in the cans are made as just described under the head of 

 apparatus for changing the water. In our case, the water was changed 

 every two hours, night and day, for the first half of the trip, and almost 

 every hour for the last half. As we had eight cans of fish, and were seven 

 days and nights on the way, we made almost a thousand changes of 

 water. The labor, of course, was almost incessant. It was like walking 

 a thousand miles in a thousand hours. 



Temperature of the icater. — It has been ascertained that a lower degree 

 of temperature than G2° Fahrenheit or a higher degree than 75° Fah- 

 renheit is unfavorable to young shad. It becomes necessary therefore 

 to keep the water in the cans between these two points, viz, 62° and 75°. 

 This is done by cooling the water used for changing with ice when too 

 warm, or heating it with artificial heat when too cold. 



It is not usually a very difficult matter to obtain water of the right 

 degree for changing with, because most trips with shad are made in 

 warm weather, and in a warm climate, and the main difficulty is to get 

 the water cool enough, which can easily be done with ice. On our over- 

 laud journey, however, we passed through a very cold climate in cross- 

 ing the high ridges of the continent. Indeed, at one point on the Eocky 

 Mountains, it snowed in the day-time, although almost the 1st of July; 

 and at these high altitudes the nights were always very cold. To keep 

 the temperature of the water up to a safe point under these conditions, 

 in a cold car, with no fire in it, and with reserves of water which them- 

 selves were cold, was no easy matter, as will appear in the account of 

 the journey. Indeed, at one time there seemed to be no possible chance 

 of saving the fish, though, through the untiring labor and perseverance 

 of Mr. Perrin and Mr. Green, it was accomplished. 



Sudden changes. — Sudden changes of temperature are very injurious, 

 and often fatal, to shad. So important is the precaution thought to be of 

 guarding against this danger that an alteration of more than two degrees 



