1034 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [18] 



merit, and forwarded on the 10.20 p. m. train, by Adams Express Com- 

 pany, to M. McDonald, care Engene Blackford, Fulton Market, Nevr 

 York City. Corresponding lots remaining at the hatchery began to 

 hatch at 6 a. m. on June 6 and finished at 5 p. m. of June 8th." 



These eggs reached me in as good condition apparently as when they 

 left Washington; were transferred to McDonald jars, and were ex- 

 hibited in process of hatching before a meeting of the American Fish- 

 cultural Association, then in session at New York. 



These eggs, when shipped were forty- six hours from impregnation, 

 and the outline of the fish had begun to show plainly. It is at this stage 

 that the eggs seem to bear transportation best. The egg seems to be 

 peculiarly sensitive to injury at that period of rest which immediately 

 succeeds the granulation of the embryonic disk. Handling them at 

 this stage is almost certain to prove fatal. 



It will require further experiments in the direction above indicated 

 before we attempt a radical departure from the methods now in use ; 

 but we may expect in the near future to send eggs instead of young 

 fish to localities remote from our collecting stations, and as a package 

 containing 100,000 eggs may be sent at about the same cost as a can 

 containing 20,000 fry, the expense of distribution will thus be greatly 

 diminished. 



FLUCTUATIONS OF WATER TEMPERATURE IN THE CHESAPEAKE 



REGION. 



The diagram showing fluctuations of water temperature in the Ches- 

 apeake region furnishes very interesting and suggestive data for dis- 

 cussion. By reference to it it will be seen that, during the winter 

 months, the water temperatures on the ocean plateau, outside of the 

 capes, is higher than that of Chesapeake Bay or of the Potomac Eiver. 

 The latter part of February, or early in March, the temperature of the 

 bay waters rises above that of the ocean waters outside. Coincident 

 with this, the shad make their appearance in the Chesapeake and are 

 taken in the pounds which are set in salt water along the shores of the 

 bay. About the 1st of April the temperature of the water in the Poto- 

 mac Kiver rises above the temperature of the water in the bay. Coin- 

 cident with this is the beginning of the shad season in the river (see 

 tables of Gwynn ^arris). The lesson taught by the diagram is that 

 shad do not enter our rivers to spawn until the temperature of the river 

 waters is higher than that of the salt water from which they come. 

 The observations of 1882-'83 but repeat those of 1880-'81-'82, and con- 

 firm the conclusion already arrived at and published. ShoiTld the 

 waters of either the Potomac or the Susquehanna continue during the 

 season at a lower temperature than those of the bay, we would have no 

 run either of shad or glut herring during the season. 



