Florida Fish Species: American Shad

The American shad, a large herring, is the most abundant east coast anadromous fish. Historically, American shad probably spawned in every accessible river from the Bay of Fundy, Canada to the St. Johns River, Florida, along the Atlantic Coast. American shad spend most their life at sea, only entering fresh water to spawn. At sea, shad form huge schools feeding on plankton and small shrimp. American Shad were introduced into the San Francisco Bay/Sacramento River system in California in the 1800s. They have spread up the coast and currently a large population spawns in the Columbia River.
 
American Shad have a greenish-blue metallic look long the back and are silvery along the sides.  They have a row of dark spots along its side.  The shoulder spots are the most noticeable.  Their underside is covered with sharp saw-like scales or "scutes." The lower jaw does not extend past the upper jaw. American shad are typically 20 to 24 inches in length.  They can spawn multiple times and live past ten years of age.
 
Sexually mature fish enter rivers and streams in spring or early summer when water temperatures are in the low fifties. Thus the spawn is progressively later as you move north, starting in Northern Florida/Southern Georgia around January and ending in June for Canadian waters.
In larger rivers they may run far upstream to their spawning grounds.
 
Sandy or pebbly shallows are used to lay their eggs.  Most spawning occurs between sundown and midnight. The eggs are released in batches. The transparent eggs are pale pink or amber. Being semi-buoyant and not sticky, they roll with the current. The eggs hatch in within one to two weeks depending on the water temperatures. The young shad remain in the rivers until fall, when they move down to salt water.
 
Juveniles feed on zooplankton and terrestrial insects while in the rivers.  Adults feed on plankton, small crustaceans, and small fish but do not feed while migrating upriver to spawn.
 
American shad may spawn once and die, or some may survive to make several spawning runs per lifetime. Spawning survival seems to be dependent on latitude, with more northerly fish more likely to spawn multiple times.