Abalone: Up Close and Personal
Abalone (from Spanish Abulón) are medium to very large-sized edible sea snails, marine gastropod mollusks in the family Haliotidae and the genus Haliotis. The common "red" abalone in our area is Haliotis rufescens. It is one of about 100 different species worldwide, some commonly called black, white, pink and green for their predominant shell color or hue.
The color of the shell is very variable from species to species. The iridescent nacre that lines the inside of the shell varies in color from silvery white, to pink, red and green-red, through to Haliotis iris, which shows predominantly deep blues, greens and purples.
These sea snails cling solidly with their broad muscular foot to rocky surfaces near or just below the low tide level (sublittoral depth). They reach maturity at a relatively small size and their fecundity is high and increases with their size (from 10,000 to 11 million eggs at a time). Although abalones produce large numbers of eggs and sperm, reproductive success is very sporadic. The last major successful reproductive period for northern California red abalone was probably in the late 1980s.
The adults feed mostly on red or brown algae. A series of small holes on top of the shell are used to expel sex products and waste. About 1/3 of the weight of the animal is meat, 1/3 is offal, and 1/3 is shell.
The shell of the abalone is exceptionally strong. It is made of microscopic calcium carbonate tiles stacked like bricks. Between the layers of shells is a clingy protein substance. When the abalone shell is struck, the tiles slide instead of shattering and the protein stretches to absorb the energy of the blow. Material scientists around the world are studying the tiled structure for insight into stronger ceramic products such as body armor. The dust created through the grinding and cutting of abalone shell is dangerous; appropriate safeguards must be taken to protect people from inhaling these particles.
Limited growth information is available for abalones. However, based on DFG tagging studies in the 1970’s and ongoing at present, northern California red abalones take about 7 – 12 years to reach the sport legal size of 7 inches. Growth is quite variable though, depending on food availability, habitat and competition from other large invertebrates like the red sea urchin. A 6.6 inch long abalone tagged at Van Damme by DFG in July 2006 was recently recovered in August 2009 and had only grown a half inch in the ensuing 3 years. The largest abalone recorded in California was 12.34 inches, taken in 1993 by John Pepper off the coast of Humboldt county.
The meat (foot muscle) of abalones is used for food, and the shells of abalones are used as decorative items and as a source of mother of pearl. The iridescent inner nacre layer of the shell of abalone has traditionally been used as a decorative item in jewelry, buttons, and as inlay in furniture and in musical instruments such as guitars, etc.
Abalone pearl jewelry is very popular in New Zealand and Australia, in no minor part due to the marketing and farming efforts of pearl companies. Unlike the Oriental Natural, the Akoya pearl, and the South Sea and Tahitian cultured pearls, abalone pearls are not primarily judged by their roundness. Also, unlike other types of pearls, abalone pearls are not subjected to any type of processing, such as bleaching or buffing.
Abalone has long been a valuable food source for humans in every area of the world where a species is, or used to be, abundant. The various larger species of abalones have been exploited commercially for food to the extent that many populations are now severely threatened.
The meat of this mollusk is considered a delicacy in certain parts of Latin America (especially Chile), France, New Zealand, South East Asia, and East Asia (especially in China, Japan, and Korea). In Chinese speaking regions, abalone are commonly known as bao yu, and sometimes forms part of a Chinese banquet. Similar to shark fin soup or birds nest soup, it is considered a luxury item, and is traditionally reserved for special occasions.
Throughout its life, an abalone contends with a variety of predators. The eggs and larvae are eaten by filter-feeding animals. Though juvenile abalone hide, they are active at night (nocturnal) and crabs, lobsters, octopuses, starfish, fish and predatory snails prey on them. Abalone in shallow water may be crushed by storm tossed rocks.
Large abalone are not threatened by the predators of their earlier life, but larger, and often more efficient predators now become important. Fishes, such as the cabezon, can dislodge some abalone and swallow them whole. Even very large abalone are no match for the crushing jaws of a bat ray.
The sea otter is the most effective predator, capable of removing all exposed abalone within reach. Only those in deep crevices or under large rocks will survive. Abalone are one of the first food items taken by otters as they move into new habitat. However, in areas outside of the sea otter range, in southern California, overharvest by the commercial fishery and disease are considered the primary causes of abalone population declines. In northern California, fishery monitoring by the DFG indicates that populations are relatively stable and that abalones in the deep water refuge beyond the range of most free divers may act to replenish shallower stocks. Now, you’re not quite done...
California Department of Fish and Game: