Abalone
Description
Abalones are members of a large class (Gastropoda) of molluscs having one-piece shells. They belong to
the family Haliotidae and the genus Haliotis, which means sea ear, referring to the flattened shape of the
shell.
Abalone shells are rounded or oval with a large dome towards one end. The shell has a row of respiratory
pores. The muscular foot has strong suction power permitting the abalone to clamp tightly to rocky
surfaces. An epipodium, a sensory structure and extension of the foot that bears tentacles, circles the foot
and projects beyond the shell edge in the living abalone. Nine species of abalone occur in North America:
black (H. cracherodii), flat (H. walallensis), green (H. fulgens), pink (H. corrugata), pinto (H.
kamtschatkana), red (H. rufescens), threaded (H. assimilis), Western Atlantic (H. pourtalesii), and white
(H. sorenseni) abalone.
Black abalone (H. cracherodii) have black and smooth epipodium and tentacles. The shell surface is
black or dark blue, and smooth. There are 5 to 9 open pores, and the pores are flush with the shell
surface. Black abalone range from Mendocino County, California to southern Baja California. They are
found in intertidal and shallow subtidal zones down to a depth of about 20 feet. Black abalone reach 7.75
inches in length, but are commonly 5 to 6 inches long.
Flat abalone (H. walallensis) have a mottled yellowish and brown epipodium, with a pebbly appearing
surface and lacy edge. The tentacles are greenish and slender. The shell is flattened, narrow, and
marked with low ribs. There are 5 to 6 open pores, and the pore edges are moderately elevated above
the shell surface. Flat abalone range from British Columbia, Canada to San Diego, California. They are
found in the subtidal zone from 20 feet down to at least 70 feet. Flat abalone reach 7 inches in length, but
are commonly under 5 inches.
Green abalone (H. fulgens) have a mottled cream and brown epipodium, with tubercles scattered on the
surface and a frilly edge. The tentacles are olive green. The shell is usually brown, and its surface marked
with many low, flat-topped ribs that run parallel to the pores. There are 5 to 7 open pores, and the pore
edges are elevated above the shell surface. A groove often parallels the outer edge of the line of pores.
Green abalone range from Point Conception, California to Bahia Magdalena, Baja California. They are
found in the intertidal and subtidal zones down to at least 30 feet. Green abalone are often found in
crevices where surfgrass and algal cover is dense. They reach 10 inches in length, but are generally
smaller.
Pink abalone (H. corrugata) have a mottled black and white epipodium with many tubercles on the
surface and a lacy edge. The foot is yellow to light orange. The tentacles are black. The shell is thick and
its surface is marked with wavy corrugations. There are 2 to 4 open pores, and pore edges are strongly
elevated above the surface. Pink abalone range from Point Conception, California to Santa Maria Bay,
Baja California. They are found in the subtidal zone from 20 feet down to at least 120 feet, commonly in
beds of giant kelp. Pink abalone reach 10 inches in length, but individuals over 7 inches long are now
rare.
Pinto abalone (H. kamtschatkana) have a mottled pale yellow to dark brown epipodium, with a pebbly
appearing surface and lacy edge. Tentacles are yellowish brown, or occasionally green, and thin. The
shell is irregularly mottled and narrow. There are 3 to 6 open pores, and the pore edges are elevated
above the shell surface. A groove often parallels the line of pores. Pinto abalone range from Sitka, Alaska
to Monterey, California. They are found in the intertidal and subtidal zones down to at least 70 feet. Pinto
abalone reach 6.49 inches in length, but are commonly 4 inches long. Pinto abalone are also known
regionally as northern abalone.
Red abalone (H. rufescens) usually have a black epipodium, but some specimens have a barred black
and cream pattern on their epipodium. The surface of the epipodium is smooth and broadly scalloped
along the edge. The area around the foot is black and the sole is tan to grey. The tentacles are black. The
shell surface is generally brick red and the inside edge is often red. There are 3 to 4 open pores, and the
pores are moderately elevated above the shell surface. Red abalone range from Sunset Bay, Oregon to
Tortugas, Baja California. North of Point Conception, they are found in the intertidal and subtidal zones
down to at least 60 feet. South of Point Conception, they are found in the subtidal zone down to over 100
feet. Red abalone reach 12.3 inches in length, but are commonly 7 to 9 inches long.
Threaded abalone (H. assimilis) have a mottled pale yellow to dark brown epipodium with a pebbly
appearing surface and frilly edge. The tentacles are yellowish brown, short and thin. The shell is oval and
the surface is marked with prominent ribs interspersed with narrow ones. There are 4 to 6 open pores,
and the pores are moderately elevated above the shell surface. Threaded abalone range from San Luis
Obispo County, California to Bahia Tortugas, Baja California. They are found in the subtidal zone from 20
feet down to at least 80 feet, commonly on rock surfaces. Threaded abalone reach 6 inches in length, but
are commonly smaller. Threaded abalone are considered a subspecies of the pinto abalone by some
scientists.
Western Atlantic abalone (H. pourtalesii) have a yellowish epipodium with large and small sensory
tentacles. The sole of the foot is tan. The shell is reddish-orange. Western Atlantic abalone range from
North Carolina through the Gulf of Mexico to Brazil. They are found from 187 feet down to at least 1,200
feet on hard substrates. The largest recorded shell had a length of about 1.2 inches.
White abalone (H. sorenseni) have a tan and pebbly epipodium. The sole of the foot is orange. The shell
is deep, thin and oval. There are 3 to 5 open pores, and the edges of the pores are elevated above the
shell surface. White abalone range from Point Conception to Bahia Tortugas, Baja California. Most white
abalone are found in the Channel Islands in California. White abalone are found in the subtidal zone
down to at least 200 feet. They are commonly found in open, exposed areas. White abalone reach 10
inches in length, but are commonly 5 to 8 inches long.
Natural History
Abalones reach sexual maturity at a small size, and fertility is high and increases exponentially with size.
Sexes are separate and fertilization is external. The eggs and sperm broadcast into the water through the
pores with the respiratory current. A 1.5 inch abalone may spawn 10,000 eggs or more at a time, while an
8 inch abalone may spawn 11 million or more eggs. The spawning season varies among species with
black, green and pink abalone spawning between spring and fall, and pinto abalone spawning during the
summer. Red abalone in some locations spawn throughout the year. The fertilized eggs hatch into
floating larvae that feed on plankton until their shells begin to form. Once the shell forms, the juvenile
abalone sinks to the bottom where it clings to rocks and crevices with its single powerful foot. Settling
rates appear to be variable. After settling, abalones change their diet and feed on macroalgae.
Except for black abalone, hybridization for abalone species is not uncommon in areas where several
species occur together. There are 12 recognized hybrids in southern California and northern Baja
California.
Limited growth information is available for abalones. Commercial sizes of 6.25 inches for pinks, seven
inches for greens and 7.75 inches for reds are reached after a minimum of 10 to 15 years in southern
California. Pinto abalone reach about 2.5 inches in a minimum of 6 years.
Juvenile abalones feed on rock-encrusting coralline algae and on diatom and bacterial films. Adult
abalones feed primarily on loose pieces of marine algae drifting with the surge or current. Large brown
algae such as giant kelp, bull kelp, feather boa kelp and elk kelp are preferred, although other species of
algae may be eaten at various times.
Abalone eggs and larvae are consumed by filter-feeding fish and shellfish. Predators of juvenile abalones
include crabs, lobsters, gastropods, octopuses, seastars, and fishes. The bat ray in southern California
and the sea otter in central California prey selectively on larger abalones.
Production
In decreasing order of total catch between 1950 and 1995, red (46.6%), pink (41.2%), black (8.7%), green
(3.5%), and white (>1%) abalones have all been harvested in California. Since 1993, only red abalone
have been taken commercially, and the Fish and Game Commission closed all red abalone harvest south
of San Francisco in May 1997. Pinto abalone are commercially harvested in Alaska and British Columbia.
Flat and threaded abalones have limited distributions and neither is common. The western Atlantic
abalone is rare and is not fished commercially.
Aquaculture of red, pink, and green abalones occurs in California. There is limited aquaculture of green
and H. diversicolor supertexta abalones in Hawaii.
California. The commercial fishery for abalones in California began in the 1850's. Chinese Americans
initially harvested intertidal green and black abalones with skiffs using long, hooked poles. This fishery
was eliminated in California in 1900 by closure of shallow waters to commercial harvest. Japanese
American divers followed the Chinese Americans as the fishery moved to the subtidal zone. Initially, free
divers working from barrel floats harvested abalones. Later, hard-hat divers harvested abalones from
deeper waters. In the late 1950's, "hooka" gear, which supplied air from the surface to divers using light
masks, fins and wet suits, began replacing hard-hat gear. Since the 1970's, multi-hose hooka gear and
specialized, high-speed, seaworthy boats have become common in the fishery.
In California, abalone divers must use underwater diving gear consisting of an above-surface air pump
operated from a boat and at least 100 feet of air hose, and must be fully submerged while taking abalone.
Abalones may be taken only by hand or with abalone irons. An abalone iron is a flat device not more than
36" long and not less than 1/16 inch thick, with rounded smooth edges and a curve with a radius of less
than 18 inches. The commercial abalone fishery in California is managed through size limits, limits on the
number of permits for commercial abalone divers, and restrictions on harvesting areas. Minimum
commercial size limits in California are: 7-3/4 inches for red abalone, 7 inches for green abalone, 6-1/4
inches for pink or white abalone, 5-3/4 inches for black abalone, and 4 inches for pinto, threaded, and flat
abalone. Commercial harvesting is prohibited during January, February and August. A moratorium on
commercial harvesting of black abalone began in July, 1993, and extends through January 1, 1997. It is
unlikely that stocks of black abalone will recover enough for the fishery to reopen. In June, 1994, the
California Department of Fish and Game proposed and the Fish and Game Commission adopted
effective January 1, 1995 a two-year closure on sport and commercial harvesting of pink, green and white
abalone. Prices to fishermen for red abalone were around $500 to $600 per dozen in 1993-94.
The California commercial abalone harvest reached a record 5.4 million pounds in 1957. Since then,
commercial harvests have declined dramatically to about 461,376 pounds in 1993. Current stocks of most
abalone species in central and southern California are over utilized. This is the combined result of
commercial harvest efficiency, increased market demand, sport fishery expansion, an expanding
population of sea otters, pollution of mainland habitat, unexplained mortalities of black abalone due to a
condition known as "withering syndrome," and loss of kelp populations associated with El Niño events.
Management efforts through size limits and limits on commercial harvesting permits have been
ineffective. Reseeding experiments have not been successful. Commercial abalone harvesting in
California may be eliminated if the sea otter range is not contained. Studies in a California fishery reserve
have shown that even protected populations cannot support a fishery within the sea otter range in central
California. New laws pending in the 1997 Legislature would establish a multi-year moratorium on the
commercial and recreational harvest of all species of abalone south of the entrance to San Francisco Bay
until stocks have demonstrated some level of recovery and a new management plan is in effect.
Alaska. The southeast Alaska commercial abalone fishery was sporadic and local prior to 1971. Shore
picking was the primary harvesting method, but after 1960 some scuba gear was used. The fishery
increased dramatically during the 1970's due to improved scuba gear, increased product demand, and
the use of larger vessels. The Alaska abalone harvest reached a record 315,000 pounds in 1978-79, and
then fell to about 36,000 pounds in 1992-93 when a minimum size limit was instituted. The Alaska pinto
abalone fishery is managed through guideline harvest ranges, a minimum legal size of 3.75 inches, a
restrictive season, and local area closures for conservation and food fisheries. The fishery opens in
October to remain outside spawning and settling periods. Guideline harvests prior to 1988-89 varied
33,000 to 57,000 pounds per year. The season was shortened each year, and in 1993-94 the most
productive areas were closed after 6 days and a catch of 37,000 pounds.
British Columbia. Prior to 1971, the British Columbia commercial pinto abalone fishery was sporadic
and local. Shore picking was the main harvest method, but after 1960 some scuba gear was used. The
fishery accelerated rapidly during the 1970's due to improved scuba gear, reduced access to herring and
salmon fisheries, acceptance of the pinto abalone in the Japanese market, increased product demand,
and the introduction of larger vessels with freezer capacity. Abalone landings peaked in 1977 at 474.8
metric tons and then declined rapidly. The fishery was later closed to rebuild stocks.
Products
During the early years of the abalone fishery, abalones were dried and smoked, or canned for export, and
sold fresh for local markets. Currently, most abalones are exported to Japan, either fresh or frozen whole.
The U.S. market is primarily in California for live abalone for the sashimi market, and for some fresh and
frozen steaks for restaurants.
A major shift in U.S. marketing occurred after the black abalone moratorium in 1993. Red abalone became
the primary export product. High prices increased the incentive for illegal harvesting in closed areas.
Abalone steaks are produced by removing the foot, trimming, slicing, and tenderizing. Yield from a live
abalone is roughly 15 percent. Shells are used for mother-of-pearl, souvenirs, and jewelry.
References
(References section preserved exactly as in the PDF.)