MANUAL OF FISH-CULTURE. 137 



found full of these eggs of different sizes. Shortly before spawning, 

 transparent eggs of large size, contrasting strongly with the opaque 

 golden hue of less mature ones, will be found scattered through the still 

 compact ovarian mass, antl becoming more and more numerous, the 

 ovaries disintegrate, the eggs fall apart, and extrusion begins, a liquid 

 stream of eggs and mucus flowing from the oviduct on the slightest 

 pressure of the abdomen. 



Freshly deposited shad eggs are of a pale amber or pink color, and 

 are transparent. They are about -]\- inch in diameter and somewhat 

 flattened and irregularly rounded in form. The egg membrane is much 

 wrinkled and lies in close contact with the contained vitellus. Imme- 

 diately after fertilization the egg becomes spherical through the absorj)- 

 tion of water and apparently gains very much in bulk, measuring from 

 ^ to I inch in diameter; but this gain is only the distended egg mem- 

 brane, the vitellus or true germinal and nutritive portion not having 

 increased. The vitellus is heavier than water, and a large space tilled 

 with fluid now exists between it and the membrane, the vitellus rolling 

 about and changing its position as the position of the egg membrane is 

 altered. Fo adhesive material is found on the outside of the membrane, 

 though when first extruded the eggs are covered with a somewhat sticky 

 ovarian mucus. 



In a state of nature the shad deposits its eggs loosely in the rivers 

 without building a nest, the two sexes running along together from 

 the channel towards the shore, and the eggs and milt being ejected 

 simultaneously. On quiet evenings, at the height of the season, 

 spawning shad may be heard surging and plunging along the shores. 

 By fishermen this is termed "washing." 



Shad are very prolific, but much less so than many other food-fishes. 

 The quantities of eggs taken by spawn-takers do not represent the 

 actual fecundity, for many are cast in advance of stripping. The 

 average number is not more than 30,000. Single fish have been known 

 to yield G0,000, 80,000, 100,000, and 115,000 eggs; and on the Delaware 

 Eiver, in 1885, one yielded 150,000. Many eggs fail to be fertilized, 

 and but a comparatively small percentage of those impregnated are 

 hatched. After being extruded, the eggs sink to the bottom, where 

 they remain until hatched, subject to the attacks of fish and other 

 water animals. Eels are very destructive to shad spawn and often 

 attack shad caught in gill nets, devouring the undeposited eggs and 

 sometimes mutilating half the catch of a gill net fisherman. 



The development of fungus is one of the greatest dangers to shad 

 eggs in a natural state, and another potent agency for their destruction 

 is the mud brought down by heavy rains, burying and suffocating 

 the eggs. 



After spawning, shad are denominated "down-runners," "racers,'' 

 and "spent fish." They are then very lean and hardly tit for food, but 

 they begin to feed and have become fatter by the time they reach salt 

 water in the summer or fall. 



