606 NATUEAL HISTORY OF AQUATIC ANIMALS. 



increase in proportion as the season advances. The favorite spawning grounds of the Shad, or 

 " Shad Wallows," as they are termed by the fishermen, are on the sandy flats which border the 

 streams, and the sand-bars which are found at intervals higher up the river. When the fish have 

 reached suitable spawning grounds and are ready to cast their eggs, they move up to the flats 

 seemingly in pairs. The time of this movement is usually between sundown and 11 p. in. When 

 in the act of coition they swim close together and near the surface, their back fins projecting above 

 the water. The rapid, vigorous, spasmodic movements which accompany this operation produce 

 a splashing in the water which can be plainly heard from the shore, and which the fishermen 

 characterize as "washing." 



The eggs are spun out by the female while in rapid motion. The male, swimming close to 

 her, ejects his niilt at the same time, and the contact of egg and milt, and the consequent impreg- 

 nation of the egg, is coincident with or immediately subsequent to the ejection of the ova from the 

 female. The specific gravity of the egg being slightly greater than that of water, it sinks to the 

 bottom, and, under favorable conditions, develops and hatches out. Large numbers of these eggs 

 are, of course, destroyed by the predaceous fishes that have learned to frequent the spawning 

 grounds of the Shad. A sudden lowering in the temperature of the water may, and frequently 

 does, produce a large destruction of eggs. Floods, too, bring down mud which may smother and 

 destroy vast numbers. But, escaping these casualties, they hatch out in a period of from three to 

 eight days. Unlike the Salmonidce, although with a sac' relatively as large, the new-born Shad 

 swim vigorously as soon as they break the shell, and, according to Mr. Seth Green, make their 

 way immediately to the middle of the stream, where they are too small to be an object of prey to 

 the larger fishes, and where the smaller ones dare not come after them. 



The number of eggs in the ovary of a Shad, as in all other fish, bears a certain relation to the 

 size and weight of the fish. As the result of experience iu the artificial propagation of the Shad we 

 conclude that a ripe roe Shad weighing four or five pounds contains from 20,000 to 40,000 eggs, the 

 average number being about 25,000. A much larger number, however, has been obtained from 

 some individuals. In the season of 1881 we obtained from a single Shad, weighing about six 

 pounds, over 60,000 impregnated eggs; again, in 1880, on the Potomac River, the yield of eggs from 

 a single Shad was over 100,000. These were full-sized, thoroughly impregnated, and were hatched 

 out with a loss of hardly one per cent. 



SIZE. A female Shad of a certain age is always larger than a male of corresponding age. A 

 general average for both sexes along the whole coast would be about four pounds, the extremes 

 for males being from one and a half to six pounds, and for females from three arid a half to eight 

 pounds, the latter representing a maximum weight for Shad at the present time ; although, iu the 

 early history of the fisheries, there are records of the capture of fish weighing eleven, twelve, and 

 as much as fourteen pounds. These extreme figures, of course, are for fish which, in consequence 

 of the imperfections of the ordinary kinds of fishery apparatus, the want of skill on the part of the 

 lishermeu, or the accidents of fortune have escaped for a long period the fate which befel their less 

 happy companions and have returned to the rivers year after year. 



FOOD. The shad fry, which spend the first six months in our rivers, must ot necessity find their 

 food therein. From examinations made of the stomachs of these young fish, they have been 

 found to feed upon certain species of Crustacea and insect larva?, common to the fresh waters 

 of our rivers. During the spring of 1882 some young fry, which were hatched out at Central 

 -station, were confined by Dr. John A. Ryder in a glass aquarium, through which the circulation 

 of the water was maintained, and fed with Copepoda, obtained in large quantities from the 

 United States carp ponds. In about seven days after hatching some of the young fry were 



