THE HERRING AND ITS ALLIES. 
401 
taries of the Chesapeake and Delaware Bays. These fish have undoubtedly 
been born and bred in southern waters, and their appearance so far north 
would indicate that occasionally this southern variety strays beyond its 
normal range. At one time it was imagined that the whole body of 
American Shad, having wintered in the south, started northward with the 
new year, and as each river mouth was reached a detachment would leave 
the entire mass for the purpose of ascending the river, the last remaining 
portion of the immense school entering the Gulf of St. Lawrence. 
At a later date it was thought more reasonable to suppose that the young 
fish, hatched out in any particular stream, went out into the sea and re¬ 
mained within a moderate distance of the coast until the period again 
occurred for their upward river migration. Their appearance, first in the 
extreme southern river of the coast, the St. John’s, and at later dates suc¬ 
cessively in the more northern rivers, was thought to confirm this view. It 
will be seen, in the discussions of the relation of the movements of the 
Shad to the water temperature, published in the reports of the United 
States Fish Commission, that this order of appearance when preserved 
may be reasonably accounted for; there are, however, exceptions. 
For instance, the Edisto River is many miles north of the Savannah, and 
yet the run of Shad in the former is usually coincident with that in the 
latter. This leads us to believe that the Shad are generally distributed 
along the coast at all times, entering the rivers as soon as the temperature 
of the water is suitable. It is but natural that the waters of a creek or 
short stream, not having its source in the mountains, should in the spring 
become warm long before those of a large river whose headwaters are far 
up among the mountains; for which reason we may expect to find, in the 
case of two rivers, the most southerly of which has a longer water-course 
than the other, that the Shad will first enter the more northerly, yet 
shorter, and consequently, at a given date, warmer stream. The question, 
therefore, appears to be rather one of temperature than of geographical 
location. 
The greater portion of the life of the Shad being spent in salt water, the 
possibility of close observation as to their food, habits, or precise habitat 
is precluded. The young fry, hatched out in the rivers in spring and early 
summer, remain there until the following fall, when, the temperature of 
the waters having fallen below 6o°, they leave for the ocean. Nothing 
more is seen of them until they return to the rivers as mature fish for the 
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