Abalone

• 1. Introduction

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  Abalone are sea snails in the genus Haliotis, and each shell carries a curved row of small holes near its edge. Turn the shell over and the inside glows with silver, pink, green and deep blue. This one animal appears in banquet halls, in materials laboratories and in courtrooms. Why does a snail's shell have holes? What makes its armor so hard to break? And how did a creature clinging to rocks become valuable enough to farm, to regulate and to steal?

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• 2. Anatomy and Armor

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  Between eight and 38 holes can line an abalone shell, though only a few are open at one time. They form a band called the selenizone, set into a groove pressed by a cleft in the animal's mantle. Older holes seal over as the shell grows, and new ones open near the front edge. Each species typically keeps between four and 10 open. Water from the gills leaves through them, and so do sperm and eggs.

  Most shells are convex and rounded to oval, with a small flat spire and two to three whorls. The last whorl is called the body whorl, and its ear-like outline gives the animal the name ear shell. Haliotis asinina is more elongated than its relatives. Haliotis cracherodii cracherodii is oval, with no perforations, a protruding spire and prickly ribs. The outside of a shell is striated and dull, and its color varies between species, possibly reflecting diet. The glow inside comes from nacre, the thick inner layer that people have long prized as mother-of-pearl.

  Size ranges from about 20 millimetres in Haliotis pulcherrima to roughly 200 millimetres in larger species. The largest of all, Haliotis rufescens, reaches 300 millimetres, which is 12 inches. The rounded foot is very large compared with most molluscs, and it grips rock below the low-tide line. Haliotis cracherodii was once common in the intertidal zone. Adults are herbivores that scrape macroalgae with a toothed ribbon called a radula, and they prefer red or brown algae. An abalone matures at a relatively small size and can lay anywhere from 10,000 to 11 million eggs at a time.

  The shell is exceptionally strong. It is built from a tightly packed calcium carbonate matrix with a protein layered through it. A force applied directly to the shell tends to shed layers rather than crack or shatter it. Material scientists are studying this design for ablative protective tools such as body armor. Workers who grind and cut the shell must be protected from breathing in the dust, which is dangerous.

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• 3. Names and Origins

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  The word abalone reached English through Spanish, as abulón, which came from aulón in Rumsen. Around the world the animal carries many other names. Australians in some regions once called it muttonfish or muttonshell, though that is now rare. In the United Kingdom it is the ormer, in South Africa the perlemoen, and in New Zealand the pāua.

  Counting species is harder than naming them. Recognized totals range from 30 to 130, depending on the source consulted. As of 2025, MolluscaBase accepts 76 living species and 25 fossil species.

  Abalone live along the coastal waters of every continent, with a few gaps. They are absent from the Pacific coast of South America, the Atlantic coast of North America, the Arctic and Antarctica. Most species favor cold water, such as the seas off New Zealand, South Africa, Australia, Western North America and Japan.

  Scientists place abalone in the clade Vetigastropoda, but their exact position inside it is uncertain. The earliest known fossils date to the Campanian age of the Late Cretaceous. All of the few Cretaceous specimens come from North America, which hints at an origin there. Another idea points to the central Indo-Pacific, where abalone are most diverse today. A fossil called Trochotoma frydai, found in Spain, closely resembles the Cretaceous abalone Haliotis antillesensis. The one difference is a slit where the abalone has a row of holes.

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• 4. Ancient Ornament

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  Abalone shell turns up in 100,000-year-old deposits at Blombos Cave in South Africa. People have gathered these animals for food and beauty since prehistory. They made jewelry, buttons, buckles and inlay from the shell, and they also used the claw-like pearls and the nacre.

  Chinese abalone middens survive on California's Northern Channel Islands. For at least 12,000 years, harvesting there was heavy enough that the local shells grew smaller, a change visible by four thousand years ago.

  In a number of Indigenous cultures, particularly in Africa and on the Northwest American coast, abalone has been a staple. The meat is a traditional food and the shell becomes ornaments. In some communities the shells were once used as currency.

  The iridescent nacre also decorates furniture and musical instruments. It appears as inlay on the fret boards of guitars and along their binding.

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• 5. Prized at the Table

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  In Greater China and among overseas Chinese communities, abalone is known as bao yu. It can appear at a Chinese banquet as one of the four sea delicacies. Like shark fin soup and bird's nest soup, it counts as a luxury item, traditionally saved for celebrations.

  In Japan, live raw abalone goes into sushi under the name awabi. It is also served steamed, salted, boiled, chopped or simmered in soy sauce. On Honshū, salted and fermented entrails become a local dish called tottsuru, which is mainly eaten with sake. South Korea calls the animal Jeonbok. Cooks there make it into porridge, pan-fry it as a steak with butter, or add it to soups and ramyeon. Chile, France, New Zealand and parts of East and Southeast Asia also treat it as a delicacy.

  California has its own habits. Abalone meat appears on pizza, sautéed with caramelized mango, or as a steak dusted with cracker meal and flour. Chinese immigrants were the main gatherers and cooks of abalone in the United States, after Native American tribes had long used it. In 1900 California passed laws banning the taking of abalone above the intertidal zone. That pushed the Chinese out of the trade, and Japanese divers, with or without gear, perfected the work and took their place.

  The Panama-Pacific International Exposition of 1915 helped make abalone popular. It displayed 365 varieties of fish, ran cooking demonstrations and had a dining hall with 1,300 seats. As abalone grew more popular and less common, prices rose. A restaurant portion of about four ounces cost the equivalent of US$7 in the 1920s, adjusted for inflation. By 2004 the same portion cost US$75.

  The name sells so well that a different mollusc, Concholepas concholepas, is often marketed in the United States as Chilean abalone. It is not an abalone at all but a muricid.

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• 6. Farms and Reefs

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  Raising abalone for meat began in the late 1950s and early 1960s in Japan and China. Since the mid-1990s, commercial farms have grown steadily more successful. Overfishing and poaching have cut wild populations so far that farmed animals now supply most of the abalone meat eaten.

  The main farming regions are Mainland China, Taiwan, Japan and South Korea. Farms also operate in Australia, Canada, Chile, France, Iceland, Ireland, Mexico, Namibia, New Zealand, South Africa, Spain, Thailand and the United States.

  Flinders Bay in Western Australia hosts a different approach. After trials in 2012, a commercial sea ranch was set up there on an artificial reef. The reef is made of 5,000 separate concrete habitat units, and each unit can hold 400 abalone. Young abalone from an onshore hatchery are seeded onto it. The animals graze on seaweed that grows naturally on the units.

  The bay itself has changed as well. Its enriched ecosystem now supports growing numbers of dhufish, pink snapper, wrasse and Samson fish.

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• 7. Rules of the Harvest

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  Tasmania supplies about 25% of the world's yearly abalone harvest. Around 12,500 Tasmanians fish recreationally for blacklip and greenlip abalone. Blacklip minimum sizes run from 138 millimetres in the south to 127 in the north. Greenlip must measure 145 millimetres, except near Perkins Bay, where the minimum is 132. A licence allows 10 per day and 20 in possession. Scuba diving for abalone is allowed in Tasmania. In New South Wales and Western Australia it is illegal, and free-divers there may take only two.

  Victoria has fished abalone since the late 1950s, working three zones with divers on surface-supplied air hoses. Since 2002 catches have fallen sharply. The total allowable catch dropped from 1440 to 787 tonnes for the 2011-12 fishing year, because of dwindling stocks and a fast-spreading, lethal virus.

  California's rules grew tighter year by year. In 2008 a permit card came with 24 tags, a limit cut to 18 in 2014 and to 12 by 2017. Only red abalone may be taken, and only by breath-hold diving or shore picking. In 2018 the state closed the recreational season because populations were declining dramatically. The closure was extended through April 2021, then to April 2026. In December 2025 it was extended another 10 years, until April 2036. The largest abalone recorded in California measured 12.34 inches. John Pepper caught it off San Mateo County in September 1993.

  In New Zealand, pāua may be taken without a permit if limits are followed. The daily limit is 10 per diver, with minimum shell lengths of 125 millimetres for Haliotis iris and 80 millimetres for Haliotis australis. No one may hold more than 20 pāua or 2.5 kilograms of meat. Only free-diving is legal.

  The British Channel Islands and the nearby coasts of Brittany and Normandy treat the ormer, Haliotis tuberculata, as a delicacy. Gathering, called ormering, is limited to ormering tides between the 1st of January and the 30th of April. These fall on the full or new moon and the two days after. Ormers under 80 millimetres must stay on the beach, and gatherers may not wear wetsuits or put their heads underwater. Breaking these rules can bring a fine of up to £5,000 or six months in prison. A Mr. Kempthorne-Leigh of Guernsey was arrested by a police officer in full diving gear, for illegal diving for ormers. It is described as the world's first underwater arrest.

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• 8. Poachers and Peril

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  A large global black market trades in abalone meat. In New Zealand, poaching is a major industry, with many thousands taken illegally and often undersized. The right to harvest pāua can be granted legally under Māori customary rights, and abuse of those permits is hard to police. Roving fishery officers of the Ministry for Primary Industries enforce the limits with backing from the New Zealand Police. Convictions have meant seized diving gear, boats and vehicles, fines and, rarely, prison.

  Haliotis midae, South Africa's largest abalone, lives along roughly two-thirds of the country's coastline. Illegal commercial harvesting now threatens its stocks. In 2007 the government listed abalone in CITES Appendix III, which asks member governments to monitor trade. South Africa removed the listing in June 2010, though export permits are still required. Selling abalone meat inside the country is prohibited to reduce poaching. Much of the illegal meat ends up in Asian countries. In early 2008 the wholesale price was approximately US$40 per kilogram. Shells sell for more than US$1,400 per tonne.

  Nature adds its own dangers. The Victorian Department of Primary Industries said in 2007 that the disease ganglioneuritis killed up to 90% of stock in affected regions. Abalone also have very little clotting factor, so even a mild to moderate injury that pierces the skin can kill by fluid loss. Worms of the family Spionidae are known pests.

  The larger threat is overfishing combined with ocean acidification, because lower pH erodes the calcium carbonate of the shell. In the 21st century, white, pink and green abalone have joined the United States federal endangered species list. Possible restoration sites have been proposed at San Clemente Island and Santa Barbara Island. Planners have also suggested returning farmed abalone to the wild, each fitted with a special tag so the population can be tracked.

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