Figure 1. --Young shad collected with surface trawl to 

 determine distribution and growth. 



When seeking spawning grounds, shad ascend 

 some streams for great distances. In the 19th 

 century shad could ascend most streams to the 

 headwaters- -distances as great as 200 or 

 300 miles. Today dams on many streams 

 restrict shad to the stream area below these 

 barriers. 



Spawning habits of American shad are very 

 similar from river to river. Male shad usually 

 enter the stream first and swim to the spawning 

 grounds where the females later join them. 

 They begin to spawn after the water tempera- 



ture has warmed to at least 53 



and 



spawning is usually over by the time the 

 water temperature reaches 75° F. They start 

 to spawn in the evening after sunset and 

 continue to about midnight. One female is 

 accompanied by several males during the 

 spawning act. Eggs are released in open 

 water where they are fertilized by the males. 

 The spawning fish swim close together near 

 the surface with their back fins projecting 

 from the water. During spawning, the fish 

 splash vigorously; fishermen call this action 

 "washing" because of the sound. 



The eggs of shad are very easily recognized. 

 They are about one- sixteenth inch in diameter 

 when spawned but soon absorb water and in- 

 crease to about one-eighth inch. Their color 

 is transparent, pale pink, or amber, and they 

 are slightly heavier than water. The eggs 



sink and are carried along near the bottom 

 by the current. If the eggs settled on the 

 bottom, many would be smothered in the 

 silt and mud. Eggs hatch in 3 to 8 days, 

 depending on water temperature (6 days 

 at 63° F.). Each female lays from 100,000 

 to 600,000 eggs, depending on her size 

 and the stream from which she origi- 

 nates. 



For unknown reasons shad that spawn in 

 coastal streams of the South Atlantic States 

 die after spawning. North of North Carolina, 

 the nunriber of shad that survives the initial 

 spawning and returns to sea progressively 

 increases northward. The fish that return 

 again to fresh water to spawn the next year 

 are called "repeaters." 



Food and Feeding 



The food of American shad varies with size 

 and age. The young possess small teeth and 

 feed primarily on insects and crustaceans 

 during their first summer in fresh water. 

 Schools of young shad can be observed in the 

 evening feeding on insects at the surface; 

 many jump out of the water to catch flying 

 insects. During the day, the young apparently 

 feed below the surface on small crustaceans. 

 After they leave the rivers in the fall, young 

 shad lose their teeth. Then they feed on 

 plankton (small organisms) in the same manner 

 as adults, by straining water through comblike 

 structures known as gill rakers. Adult shad 

 do not feed during the spawning migration. 

 They will, however, strike artificial lures 

 when they are on their spawning grounds, 

 but biologists believe the fish are acting 

 instinctively to protect their spawning 

 grounds. 



Age Determination 



The age of shad is determined from their 

 scales, which have rings somewhat similar 

 to those on a tree. A scale from a 5-year- 

 old shad is shown in figure 2. The markings 

 or lines that lie close together and run 

 laterally across the scale are called striae. 

 The distinct marks that cross the scale 

 laterally on the same general contour as the 

 striae but are spaced farther apart are called 

 transverse grooves. The annual growth rings 

 (annuli) follow the contour of the outer edge 

 of the scale. 



Formation of an annulus is caused by slowing 

 down or cessation of growth in late winter or 

 early spring. The first ring on the scale 

 does not represent the first year and is 

 termed a false annulus. The area inside this 

 ring is called the fresh- water zone because it 

 is formed when the young shad move from 

 fresh to salt water. 



