Black abalone

Taxobox
name = Black abalone


image_width = 240px
status = CR | status_system = IUCN3.1
regnum = Animalia
phylum = Mollusca
classis = Gastropoda
ordo = Archaeogastropoda
familia = Haliotidae
genus = "Haliotis"
species = "H. cracherodii"
binomial = "Haliotis cracherodii"
binomial_authority = Leach, 1814
synonyms =
*"Haliotis expansa" (Talmadge, 1954)
*"Haliotis imperforata" (Dall, 1919)
*"Haliotis rosea" (Orcutt, 1900)
*"Haliotis splendidula" (Williamson, 1893)

The black abalone, "Haliotis cracherodii", is a species of large edible sea snail, a marine gastropod mollusk in the family Haliotidae, the abalones. [A.P.H. Oliver, 1975]

This species is relatively small compared with most of the other abalone species from the eastern Pacific, and it has a relatively smooth dark shell. This used to be the most abundant large marine mollusk on the west coast of North America, but now, because of overfishing and the Withering Syndrome, it has much declined in population.

Range of distribution

Black abalones can be found along the Pacific coast of the USA from Mendocino County, California to Cabo San Lucas, Baja California, Mexico. Prehistoric distribution has been confirmed along much of this range from archaelogical 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. [C.M.Hogan, 2008]

There is a subspecies: "Haliotis cracherodii californiensis", which is found around Guadalupe Island, off Baja California (Mexico).

Shell description

The exterior of the shell is smoother than most abalones. The coloration is dark brown, dark green, dark blue or almost black. The interior of the shell shows a pale pinkish and greenish iridescence. There are usually five to seven open respiratory holes in the shell and the rim of the holes is flush with the rest of the shell.

The black abalone's shell length can reach a maximum of 20 cm.

oft parts

In the living animal the tentacles on the epipodium, the mantle, and the foot are black.

Habitat

Black abalones 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. They are herbivores, feeding on kelp and drifiting algae.

History of Human Use

Humans have harvested black abalones 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.

Predators

Predators of this species other than mankind are sea otters, starfish, large fishes and octopuses.

Diseases

Beginning in 1985, black abalones in southern California were experiencing mass mortality due to a bacterial disease known as Withering Syndrome or abalone wasting disease. This has led to local extinction of black abalone along the California coast and contributed to the closure of commercial and sport abalone fisheries in California in 1993.

Reproduction

Black abalone have separate sexes and broadcast spawn, primarily in the Summer. Maturity is reached at about 3 years of age.

Threats and Conservation

Black abalone are threatened by overharvesting and the Withering abalone syndrome disease. California has a [http://www.dfg.ca.gov/marine/armp/ Abalone Recovery Management Plan] to guide conservation efforts. They are a U.S. National Marine Fisheries Service [http://www.nmfs.noaa.gov/pr/species/concern/ Species of Concern] . Species of Concern are those species about which the U.S. Government’s National Oceanic and Atmospheric Administration, [http://www.nmfs.noaa.gov National Marine Fisheries Service] has some concerns regarding status and threats.

In January 2008 they were [http://www.nmfs.noaa.gov/pr/pdfs/fr/fr73-1986.pdf proposed for listing as Endangered] under the [http://www.nmfs.noaa.gov/pr/laws/esa/ Endangered Species Act] . A final decision is expected by January 2009.

Line notes

References

* C. Michael Hogan, "Los Osos Back Bay", The Megalithic Portal, ed. Andy Burnham [http://www.megalithic.co.uk/article.php?sid=18353]
* A.P.H. Oliver (1975) "The Hamlyn Guide to Shells of the World", ISBN 0-600-56577-7

External links

* [http://www.gastropods.com/2/Shell_1032.html Gastropods.com]
* [http://www.piscoweb.org/outreach/pubs/abalone.html Withering Syndrome in Black Abalone]