Overview
American shad is an anadromous, migratory species found along the Atlantic coast of North America from Newfoundland to Florida.
These fish “hear” better than other fish. They have fine sensory hairs in their otoliths (similar to the ear bone), a network of water filled channels in their heads, and a swim bladder that extends up into their brain. Together, these unique features allow the shad to be extremely sensitive to movement in the water, and sensitive to noise such as the clicks and echolocation communication used by dolphins which prey on shad.
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Characteristics
Physical Characteristics
Common length for female adult shad is 24.3 in and common length for male adult shad is 19.7 inches. The maximum reported length for an American shad is 29.9 inches.
The American shad’s body isblue or green in color along the top of its body with silvery sides. At the upper side of the operculum or gill flap, a dark spot is present which is usually followed by a row of smaller spots along the upper side of the body.
The maximum published weight for American shad is 12 pounds 2 ounces.
Life Cycle
American shad is an anadromous, migratory species found along the Atlantic coast of North America from Newfoundland to Florida. They spend most of their lives in the Atlantic Ocean and return to the freshwater rivers where they were hatched, to spawn. Adults return as early as November in Florida, and in May or June in northern waters.
The peak spawning temperatures for American shad is 65.3 degrees Fahrenheit. Spawning normally occurs at sundown and until midnight.
American shad are broadcast spawners and spawn multiple times when they enter rivers. Spawning behavior typically includes several males and a female fish, swimming close together and releasing their eggs and milt simultaneously into the open water column. In southern rivers, American shad spawn for one season and then die in rivers south of North Carolina. In more northern rivers, adult American shad may migrate down river back to the ocean after spawning and can return to spawn in the same river in future years. American shad eggs are fairly small, which enables a single female adult to brood and lay up to 600,000 eggs in a spawning season.
Geography
The historic distribution of the American shad extends from southeastern Canada in Newfoundland, Nova Scotia and the St. Lawrence River south to central Florida in the U.S. They were introduced along the Pacific coast of the North America, and are now found from Cook Inlet in Alaska southward to Baja California in Mexico.