They are non-adhesive so they settle singly and are carried along by the current. After spawning, the surviving, spent adults drop back to salt water and rejoin the ocean migratory population. Larvae are about 10 mm long when they hatch, transparent and very slender. They spend their first summer in the river feeding on insects and planktonic crustacea. Shad remain at sea until they mature at age four or five years and attain a length of 40 to 50 cm.
Most males mature at age four, most females by age five.
Among Canadian populations, adults may spawn up to seven times and live to be 13 years old. The life history of an individual shad can be determined from its scales . Growth changes between fresh and salt water, winter and summer and at what age and how often the shad spawned can all be interpreted. Shad at sea feed on planktonic organisms such as copepods, mysids and euphasids. During spawning migrations, adults eat little.