MILNE R ON THE ARTIFICIAL CULTURE OF THE SHAD. 429 



fare of the young fishes. The eggs, uot only after they are deposited 

 and impregnated, but before they leave the body of the fish, are affected 

 by the temperature of the water. The spawning season of the shad 

 seems to be regulated by the increase of temperature as warm weather 

 advances. Their migrations on the coast are in quite a regular succes- 

 sion of time with relation to latitude. From letters received, from pub- 

 lished statements, tables of inspection, and personal observation, the 

 periods of their migrations are nearly as given in the following ; 

 They make their first appearance in the Saint John's River, Florida, the 

 1st of December. The season of their greatest numbers is February, 

 and they disappear in April. In the Savannah River, Georgia, it is 

 much the same. On the coast of North Carolina* they make their first 

 appearance in December, their greatest abundance is in March, and 

 they disappear in May. In the iS'euse River, North Carolina, the periods 

 of these stages of their migration are a little later. In the Potomac 

 River the advance individuals are found in February; they are found 

 most numerous in April, and they disappear early in July. They are 

 found in the Delaware River at first in March ; in the Hudson River 

 early in April. In the Connecticut River they are first found in the last 

 of April, are the most abundant the last of May, and do not leave the 

 river until late in July. In the Kennebec River, Maine, they are first 

 taken in April, and have left by the middle of July ; and the same 

 dates apply to the Androscoggin River. In the Saint John River of 

 New Brunswick t they appear about the middle of May, and in the 

 Miramichi River of the Gulf of Saint Lawrence late in May. 



But not only in the ordinary times of ascent is there evidence of their 

 sensibility to the temperature of the water, but in late seasons, when the 

 snow-water from the northern sources of the streams keeps the water 

 cold for a longer period than usual, the shad are retarded in their as- 

 cent of the rivers, and are taken in quantities by the nets near the 

 mouths of the rivers, while the fishermen above wait impatiently for 

 the run up stream that they know to be prevented by the coldness of 

 the water ; oven an entire failure in the shad-fisheries in Albert County, 

 New Brunswick, was attributed by the fisheries overseer to the extreme 

 lateness of the warm weather of spring. 



Among the Salmonidce of the great lakes the salmon-trout, (Sabno 

 namaycush, Penn.,) the white-fish, {Coregonus idhus, Les.,) and the black- 

 fin, (Coregonus nigripinnis, Gill.,) avoiding high temperatures, re- 

 main in the deep waters during the warm weather, but in early winter 

 are taken abundantly in the shoaler water near the shores. The antip- 

 athy to warm water varies to some extent, the white-fish showing the 

 least, and the black-fin the most, sensitiveness to the warmth. 



The transportation of young fishes in cans indicates this peculiarity 

 also. The Sahitonidw will thrive in a temperature as low as 40°, and 



* See Notes on the Shad, &c., by H. C. Yarrow, M. D., p. 452. 



t Article ou the Shad and Gasperean, &c., by Charles Laumun, p. 460. 



