Black Abalone

The coloration is dark brown, dark green, dark blue or almost black. The silvery interior of the shell shows a pale pinkish and greenish iridescence. The exterior of the shell is smoother than most abalone, or may have low obsolete coarse spiral lirae and lines of growth. The shell is oval, evenly convex, the two sides equally curved. The back of the shell is regularly convex, with little algal growth. The shell is not carinated at the row of holes. The spire is near the margin. The cavity of the spire is minute, concealed or nearly so. The muscle scar is generally not distinct. There are usually five to seven small, open respiratory holes, or pores, along the left side of the shell and the rims of the holes are flush with the rest of the shell. These holes collectively make up what is known as the selenizone which form as the shell grows.

Black abalone can be found along the Pacific coast of the United States from Mendocino County, California to Cabo San Lucas, Baja California, Mexico.

Prehistoric distribution has been confirmed along much of this range from archaeological recovery at a variety of Pacific coastal Native American sites. For example, Chumash peoples in central California were known to have been harvesting black abalone approximately a millennium earlier in the Morro Bay area.

The subspecies Haliotis cracherodii californiensis is found around Guadalupe Island, off Baja California (Mexico).

Black abalone are herbivorous gastropods, and feed mostly on drift algae and kelp. Their primary food species depend on the habitat. In southern California habitats, black abalone are thought to feed on the giant kelp (Macrocystis pyrifera) and feather boa kelp (Egregia menziesii), while in central and northern California habitats they feed on the bull kelp (Nereocystis leutkeana).

Black abalone cling to rocky surfaces in the low intertidal zone, up to 6 m deep. They can typically be found wedged into crevices, cracks, and holes during low tide. They generally occur in areas of moderate to high surf. Juveniles tend to reside in crevices to reduce their risk of predation, but the larger adults will move out onto rock surfaces.

Black abalone reach sexual maturity at 3 years and can live 30 years or more. Spawning occurs in spring and early summer; occasionally, a second spawn occurs in the fall. Black abalone are broadcast spawners, and successful spawning requires that individuals be grouped closely together. Larvae are free-swimming for between 5 and 14 days before they settle onto hard substrate, usually near larger individuals, where they then metamorphose into their adult form, develop a shell and settle onto a rock. Juveniles do not tend to disperse great distances, and current populations of black abalone are generally composed of individuals that were spawned locally. Juveniles settle in crevices and remain hidden until they reach approximately 4 inches in length. At that point, adults congregate in more exposed areas such as rocks and in tide pools.

Humans have harvested black abalone along the California Coast for at least 10,000 years. On San Miguel Island, archaeological evidence shows that the Island Chumash people and their ancestors ate black abalone for millennia and also used the shells to make fishhooks, beads, and ornaments. After the Chumash and other California Indians were devastated by European diseases, and sea otters were nearly eradicated from California waters by the historic fur trade, black abalone populations rebounded and attracted an intensive intertidal fishery conducted primarily by Chinese immigrants from the 1850s to about 1900.