THE HERRING AND ITS AILIES. 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 Avaters 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 60°, 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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