Black abalone
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| Black abalone | ||||||||||||||
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| Haliotis cracherodii Leach, 1814 |
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The black abalone, Haliotis cracherodii, is a species of large edible sea snail, a marine gastropod mollusk in the family Haliotidae, the abalones.[1]
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.
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[edit] 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.[2]
There is a subspecies: Haliotis cracherodii californiensis, which is found around Guadalupe Island, off Baja California (Mexico).
[edit] 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.
[edit] Soft parts
In the living animal the tentacles on the epipodium, the mantle, and the foot are black.
[edit] 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.
[edit] Predators
Predators of this species other than mankind are sea otters, starfish, large fishes and octopuses.
[edit] 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.
[edit] Reproduction
Black abalone have separate sexes and broadcast spawn, primarily in the Summer. Maturity is reached at about 3 years of age.
[edit] Threats and Conservation
Black abalone are threatened by overharvesting and the Withering abalone syndrome disease. California has a Abalone Recovery Management Plan to guide conservation efforts. They are a U.S. National Marine Fisheries Service Species of Concern. Species of Concern are those species about which the U.S. Government’s National Oceanic and Atmospheric Administration, National Marine Fisheries Service has some concerns regarding status and threats.
In January 2008 they were proposed for listing as Endangered under the Endangered Species Act. A final decision is expected by January 2009.
[edit] Line notes
[edit] References
- C. Michael Hogan, Los Osos Back Bay, The Megalithic Portal, ed. Andy Burnham [1]
- A.P.H. Oliver (1975) The Hamlyn Guide to Shells of the World, ISBN 0-600-56577-7
