Alosa

Fossils have been found in Canada, the United States, Greece, Kazakhstan, Azerbaijan, Hungary, Romania, and Italy.

[6] Alosa species are generally dark on the back and top of the head, with blue, violet, or greenish tints.

[5] Shads are thought to be unique among the fishes in having evolved an ability to detect ultrasound (at frequencies above 20 kHz, which is the limit of human hearing).

[11] They may have to pass through numerous barriers and waters to get to either their spawning grounds or normal habitats (the sea in most cases).

[11] Estuaries can be highly variable and complex environments contributing to fluctuating biological interactions,[11] with shifts in osmolarity, food sources, predators, etc.

[13] The multirakered are primarily plankton feeders, the oligorakered have large rakers and are predators, and the medium-rakered generally consume a mixed diet.

Conversely, the proposed genus (or subgenus) Caspialosa for the Caspian Sea forms is rejected due to paraphyly.

[15] Shad populations have been in decline for years due to spawning areas blocked by dams, habitat destruction, pollution, and overfishing.

On the year of every gubernatorial election, would-be candidates, lobbyists, campaign workers, and reporters gather in the town of Wakefield, Virginia, for shad planking.

American shad served as the focal point of John McPhee's book The Founding Fish.

[19] The roe, or more properly the entire engorged uterus of the American shad—filled with ripening eggs, sautéed in clarified butter and garnished with parsley and a slice of lemon—is considered a great delicacy, and commands high prices when available.

Fossil of Alosa elongata
Shad roe