Abalone Species and Threats to Them | Sea Life, Islands and Oceania

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ABALONE SPECIES

smooth Australian abalone (Haliotis laevigata), also known as greenlip abalone, whitened ear shell

There are more than 50 abalone species including Pāua Abalone, sheep's ear abalone, mule ear abalone, green abalone, pink abalone red abalone, pearl abalone, white abalone and cream abalone.

Pāua abalone (Haliotis iris) is also called blackfoot pāua or rainbow abalone. It is found almost exclusively in New Zealand, although have be found as far north as the Philippines. Pāua abalone shells are prized for their inner surface which is vividly colored in metallic blue and green, with yellow reflections. They can grow up to 18 centimeters (7 inches) in length.

Before the time of commercial fisheries, native people along California’s coast ate white, pink, red and black abalone for thousands of years. Large groups of abalone shells indicating human settlement, or “middens,” date back 7,400 years. Abalone shells were also traded along routes starting in southern California and reaching east of the Mississippi River.

Websites and Resources: Animal Diversity Web (ADW) animaldiversity.org; National Oceanic and Atmospheric Administration (NOAA) noaa.gov; Fishbase fishbase.se ; Encyclopedia of Life eol.org ; Smithsonian Oceans Portal ocean.si.edu/ocean-life-ecosystems

Red Abalone

Red abalone (Scientific name: Haliotis rufescens) ranges from southern Oregon to Baja California. They found in intertidal areas attached to rocks at depths from 6.5 to 30 meters (20-100 feet). The depths the inhabit change depending on environmental factors. In the southern parts of California, they are found deeper than 16 to 19 meters 50 to 60 feet). Farther north, closer to Oregon, they can be found from the low tide zone to about 16 meters (50 feet). They prefers water from 55̊ to 60̊ F. [Source: By Candice Middlebrook, Animal Diversity Web (ADW)]

The red abalone is the largest of all the abalone species. It has long jet-black tentacles, a large cupped mouth, and a black epipodeum which occasionally has alternating gray stripes. The outside of the large, thick shell is a dull brick red and a faint spiral that can be seen on one end. It is an asymmetrical oval in shape, broad and not very convex. There are typically three to five holes.

According to Animal Diversity Web (ADW) The gonads of the females are green and those of the male, yellowish. Spawning takes place in from the middle of February through the first weeks of April. Males eject sperm and females eject eggs (over 2 million in one spawning season) through the water. In 10 days, the free-swimming larva, called veligers, settle to the bottom and, within two months, develop into small sized adults. By the age one year, an abalone is about 2.5 centimeters (one inch) long, and within four years it reaches sexual maturity, at about 12.5 centimeters (five inches) in length.

Pink Abalone

pink abalone

Pink Abalone (Scientific name: Haliotis corrugata) are 20 to 23 centimeters (8 to 9 inches) in length. Their lifespan is About 30 Years. The range from Point Conception, California, to Bahia de Santa Maria, Baja California Sur, Mexico. They live in sheltered waters at depths between six and 36 meters (20 and 118 feet). [Source: NOAA]

The pink abalone shell is thick and more circular in shape than other abalone species. It is characterized by strong corrugations. There are 2 to 4 open respiratory pores with edges that are strongly elevated above the surface of the shell. The epipodium is a “ruffle” of tissue along the side of the foot. The cephalic (head) and epipodial tentacles are black, but the epipodial fringes are a mottled black and white, with many tubercles on the surface and a lacy edge.

Pink abalone broadcast spawn from March to November. Maturity is reached at about 1.4 inches (35 mm) length, or 3 to 4 years. Pink abalone are herbivores, feeding mostly on kelp and drift algae, and can live up to 30 years or more. [Source: NOAA]

Threatened Pink Abalone

Threats to pink abalone include fishing, disease, illegal harvest, disease (withering syndrome) and elevated water temperatures (caused by El Niño and other warm water events). Population size has declined in many areas.. In California, pink abalone fishery landings peaked in 1952 at more than 1627 metric tons. By 1990, landings had declined to 1 percent of the average reported between 1950 and 1970. In 1996, the California Department of Fish and Game (now the California Department of Fish and Wildlife) closed the commercial and recreational abalone fisheries in southern California, but populations continued to decline. [Source: NOAA]

Reduced numbers make the species vulnerable to extirpation due to a phenomenon known as the Allee effect. The Allee effect describes a situation whereby a decrease in population size leads to decreases in reproduction and survival of individuals. In the case of pink abalone, this effect is likely due to increased distance between males and females as the population density decreases, leading to reproductive failure.

Information regarding the status of pink abalone in Mexico is scant. A commercial fishery for pink abalone continues to operate in Mexico and is managed by local cooperatives. Data is deficient. Population monitoring and genetic population structure information are needed.

Northern Abalone

juvenile pink abalone

The northern abalone (Scientific name: Haliotis kamtschatkana) can be found along the Pacific coast of North America, from Baranof Island, Alaska, south to Point Conception, California. They are also found on the coast of northeast Russia and Kamchatka. They are found in greatest concentrations in substrates with moderate exposure, and moderate algal presence. Kelp forests are home to large numbers of northern abalone, but animals living in these habitats, on average, are smaller. [Source: Jesse Thomas, Animal Diversity Web (ADW)]

The northern abalone are 10 to 13 centimeters (four to five inches) on average when fully grown. The outside of the shell appears corrugated, and the spiral is fairly high compared to other abalone. There are four to five holes, which have raised edges. Reproduction is through external fertilization. Males and females synchronize the release of gametes, normally between April and June. There is a larval stage that begins after the egg has been fertilized and lasts for about 48 hours.

The most common feeding technique, especially for juveniles, is grazing for coraline algae. As individuals grow, their preference shifts to the entrapment of drifting algae. Northern abalone also graze in California's kelp forests. Red abalone and the red sea urchin are two most serious competitors of northern abalone among algal grazers. The most damaging predator to the northern abalone, other than human beings, is the sea otter. Northern abalone populations took off when sea otters were rare. The comeback of sea otters has reduced abalone populations. Northern abalone are listed as Endangered on the International Union for Conservation of Nature (IUCN) Red List. In places where harvesting them is allowed for Scuba divers are not allowed to use suction or pointed devices while hunting the abalone.

Green Abalone

Green abalone (Scientific name: Haliotis fulgens) range from Point Conception, California, to Bahia de Magdalena, Mexico. They live in shallow water on open or exposed coast from the low intertidal to at least 10 meters (33 feet) and perhaps as deep as 20 meters (66 feet). They are found in rock crevices, under rocks, and other cryptic spaces. Green abalone spawn from early summer through early fall. They reach maturity at five to seven years, and can live to 30 years or more. Being herbivores, they feed mostly on drift algae and prefer fleshy red algae. [Source: NOAA]

green abalone

Green abalone are 6.5 to 12.5 centimeters (2.4 to 5 inches) in length. Their lifespan is 30 Years or more The shell is usually brown and marked with many low, flat-topped ribs which run parallel to the five to seven open respiratory pores that are elevated above the shell’s surface. The inside of the shell is an iridescent blue and green. The epipodium is a “ruffle” of tissue along the side of the foot. The cephalic (head) and epipodial tentacles are olive green, but the epipodial fringes are a mottled cream and brown, with tubercles scattered on the surface and a frilly edge.

Due to their economic importance, green abalone have been raised in aquaculture since 1940, first at Stanford's Hopkins Marine Station in Pacific Grove, California, and more recently at various coastal facilities within southern California, primarily for the overseas restaurant trade.

Threatened Green Abalone

Green abalone has been a species of concern since 2004 because of over-harvesting. Population size has declined in many areas. In California, the commercial landings peaked in the early 1970s and have since declined precipitously. Reduced numbers make the species vulnerable to local extinction due to a phenomenon known as the Allee effect. See Pink Abalone Below. [Source: NOAA]

The primary factors contributing to the decline of green abalone are overharvest, suspected illegal harvest, and trade. Other factors include disease (withering syndrome) and elevated water temperatures (such as, due to El Niño, warm water events). In California, green abalone were targeted after the collapse of the pink abalone fishery in 1970. Landings of green abalone peaked in 1971 with more than 494 metric tons. By 1990, the landings had declined to 6 percent of the average in 1968-1972.

In 1996, the California Department of Fish and Game (now California Department of Fish and Wildlife) closed the commercial and recreational abalone fisheries in southern California, but populations continued to decline. [Information regarding the status of green abalone in Mexico is scant. Aquaculture programs have been developed to artificially enhance populations. A commercial fishery for green abalone continues to operate in Mexico and is managed by local cooperatives.

Black Abalone

black abalone

Black abalone (Scientific name: Haliotis cracherodii) weigh 0.8 kilograms 1.75 pounds and are up to 25 centimeters (8 inches) in length. They are estimated to live up to about 30 years. Adults become sexually mature in the wild when they reach about 4 to 5 centimeters (1.5 to 2 inches) in shell length. Like white abalone, they once numbered in the millions along the California coast but are now endangered. [Source: NOAA]

Black abalone live on rocky substrates in intertidal and shallow subtidal reefs to depths of about 5.5 meters (18 feet) deep along the coast. They typically occur in habitats with complex surfaces and deep crevices that provide shelter for juveniles and adults. Because they occur in coastal habitats, black abalone can withstand extreme variations in temperature, salinity, moisture, and wave action. Black abalone range from about Point Arena, California, to Bahia Tortugas and Isla Guadalupe, Mexico. They are rarely found north of San Francisco and south of Punta Eugenia. In the mid-1900s, black abalone abundances were highest south of Monterey, particularly at the Channel Islands off southern California.

The black abalone has a blackish-blue shell with five to nine holes (respiratory pores) used to breathe, remove waste, and reproduce. It also has a black-colored epipodium, an extension of the foot with tentacles used to sense the surrounding environment.

Black abalone are generally found in rock crevices. They eat different types of algae and can catch kelp drifting along the seabed or attached to rocks. Black abalone feed on giant kelp and feather boa kelp in southern California (south of Point Conception) habitats, and bull kelp in central and northern California habitats.

Declines Black Abalone

Black abalone had been important to commercial and recreational fishing in California since the mid-1800s. A large-scale commercial abalone fishery opened in California in the early 1970s, peaked in the mid-1970s, and closed in the 1990s. The fishery used size and season limits to reduce the number of abalone caught. Even with these protections, the fishery greatly decreased the abalone populations and has had long-term effects on their recovery. [Source: NOAA]

abalone fishing in Japan in the 19th century

Commercial fishery landings peaked in 1973 at nearly 900,000 centimeters (2 million pounds). By 1993, both commercial and recreational fisheries for black abalone closed because of significant population declines throughout Southern California, primarily due to mass mortalities associated with withering syndrome disease .

Beginning in the 1980s, the spread of the disease withering syndrome caused mass mortalities of black abalone, leading to dramatic declines in their numbers throughout the southern portion of the range. Today, populations in southern California remain at low densities, with signs of natural recruitment and increasing numbers at a few sites. The status of the species in Mexico remains largely unknown but is also depleted compared to historical levels due to overfishing and disease.

Black abalone populations have been monitored throughout the California coast from the mid-1970s to today, providing the primary source of information on the species’ status and trends over time. Populations are healthy along the Central and North-Central California coast, but persist at low densities or have become locally extinct in most locations south of Point Conception. Since the early 2000s, however, black abalone have been observed for the first time in many years at several sites throughout Southern California and have even increased in numbers at a few locations.

Threatened Black Abalone

Threats to black abalone include disease, low densities and reproductive rates, overfishing, sedimentation events, spills and spill response activities. Black abalone are listed as Endangered throughout their range by the U.S. Fish and Wildlife Endangered Species Act (ESA): Although fishing for black abalone has been illegal in California since 1993, the high price of abalone meat makes them a target of poachers. This species has experienced major declines in abundance throughout the Southern California coast because of historical overfishing and — more recently — mass mortalities associated with a disease known as withering syndrome. [Source: NOAA]

Illegal harvest (poaching) of black abalone continues to be a problem, particularly along remote stretches of the central California coast where numbers of black abalone are relatively high. Illegal harvest reduces black abalone abundance in the wild, further reducing the ability of populations to reproduce and sustain themselves over the long-term. [Source: NOAA]

Withering syndrome is the primary threat to black abalone. The disease is a common and fatal infection that affects the digestive organs of abalone. Although all wild black abalone are likely infected, full manifestation of the disease appears to be more prevalent in the southern portion of the black abalone range (south of Point Conception, California) where water temperatures are relatively warmer. The disease’s northward progression poses a continuing threat to the remaining healthy populations; however, the impacts may be reduced due to the potential for black abalone to develop genetically-based disease resistance, as well as the existence of a phage that infects the pathogen and improves the survival of abalone. [Source: NOAA]

black abalone, he eatable animal

One female abalone can release millions of eggs at a time but spawning males are needed to fertilize the eggs. At some locations, black abalone have declined to such low densities that the remaining animals are far from potential mates. In these cases, spawning in the wild is unlikely or happening at low levels, making natural recovery of severely-reduced populations a slow process.

Black abalone live in shallow coastal habitats that are vulnerable to chemical spills, such as oil spills. Spills and spill response activities could affect black abalone populations by directly killing or injuring animals and harming their habitat. The impacts may vary widely, depending on the type and amount of material involved, the location, local environmental conditions, and the status of black abalone populations within the spill area. We cannot predict where or when spills may occur, but can minimize the risks to abalone and their habitat through careful planning and coordination on spill response activities.

Sedimentation events can affect black abalone and their habitat through burial and runoff of toxins. In 2017, a large landslide along the central California coast buried about 1,700 meters of rocky intertidal habitat and the black abalone populations within the area. Severe fires along the Big Sur coast led to a massive debris flow event that buried additional segments of the coast and black abalone populations. Emergency response planning is underway to quickly mobilize and rescue black abalone in response to future sedimentation events.

White Abalone

White abalone (Scientific name: Haliotis sorenseni) weigh about 0.8 kilograms (1.7 pounds) and reach lengths are up to 25 centimeters (10 inches) in length. They live about 35 to 40 years. Adults become sexually mature in the wild when they are four to six years old. White abalone were once common in California. They once numbered in the millions off the California coast, but now they are endangered. [Source: NOAA]

White abalone live on rocky substrates alongside sand channels, which tend to accumulate the algae they eat. They are usually found at depths of 50 to 180 feet, making them the deepest living abalone species. Historically, white abalone were found in the Pacific Ocean from Point Conception, California, to Punta Abreojos, Baja California, in Mexico. In California, they were most abundant at offshore islands (especially San Clemente and Santa Catalina Islands) and submerged banks (primarily Tanner and Cortes Banks).

white abalone

At the southern end of the range in Baja California, white abalone were often reported along the mainland coast, but were also found at many islands, including Isla Cedros, Isla Natividad, and Isla Guadalupe. Today, researchers have found extremely low numbers of white abalone along the mainland coast of southern California, and at a few of the offshore islands and banks. The status of the species in Mexico remains largely unknown. While there is little or no recent information from Baja California, commercial fishery data suggest that the population there is also depleted. [Source: NOAA]

White abalone have a thin, oval-shaped shell with pink and red buildup on their shells.. The shell has a row of holes used to breathe, remove waste, and reproduce. The bottom of its foot — the muscle it uses to move and adhere to rocks — is orange. It also has a tan-orange epipodium, an extension of the foot with tentacles used to sense the surrounding environment. The reddish-brown color of their shells shows that white abalone eat some types of red algae throughout their lives.

Threatened White Abalone

Although fishing for white abalone has been illegal in California since 1997, the high price of abalone meat makes them a target of poachers. Commercial fishing has severely reduced white abalone numbers from historical levels. Surveys in southern California show a 99 percent decrease in the number of white abalone since the 1970s. While there were once millions, the current population is about 1,600 to 2,500 individuals. One well-studied population of white abalone in southern California decreased by about 78 percent between 2002 and 2010 (from about 15,000 individuals to just 3,000). [Source: NOAA]

California’s closure of the white abalone fishery in 1997 may have slowed the animals’ decline, but likely not by enough to recover the population. The species now faces threats from low breeding rates and disease. For example, if that well-studied population in southern California is left alone, it will likely continue to decrease by about 10 percent per year. White abalone were listed as endangered throughout their range. under the Endangered Species Act (ESA) in 2001, and were the first marine invertebrate to be listed. White abalone are one of NOAA Fisheries' Species in the Spotlight — an initiative that includes animals considered most at risk for extinction and prioritizes their recovery efforts. The black abalone is also listed as endangered under the ESA.

Due to their unique mating habits, white abalone can be depleted by intense fishing that targets groups of animals. Commercial and recreational harvest of white abalone in California peaked in the 1970s, decreased in the late 1970s to early 1980s, and closed in 1997. The fishery used size limits and seasons to reduce the number of abalone caught. Even with these protections, the fishery greatly decreased the abalone populations and has had long-term effects on their recovery. No wild white abalone have been found to have withering syndrome, but captive abalone have died from the disease and wild white abalone are known to carry the pathogen that causes it. Although disease was not a threat to abalone in the past, withering syndrome now threatens the recovery of this species.

The most significant threat to white abalone recovery is low reproduction rates. One female abalone can release as many as 10 million eggs at a time — but unless the eggs come in contact with sperm from spawning males, they cannot be fertilized. With their low population, abalone are often found alone, without potential mates nearby. This makes spawning in the wild unlikely or impossible. Wild abalone have produced few offspring since the late 1960s/early 1970s. Studies have found that abalone mortality exceeds reproduction in the wild. In a review of the status of white abalone in 2000, scientists estimated that the remaining wild white abalone would disappear without help from humans.

NOAA Fisheries is dedicated to conserving and restoring white abalone. NOAA scientists use innovative techniques to study, protect, and restore their population. They also work with partners to ensure that regulations and management plans are in place to reduce poaching and increase the wild abalone population. While white abalone are close to extinction, efforts to breed them in captivity and reintroduce them to the wild could help the species recover. NOAA runs captive breeding program with plans to reintroduce abalone into the wild and monitoring the small wild population using SCUBA and remotely operated vehicles (ROVs). NOAA is also surveying potential white abalone habitats, developing new captive breeding techniques and conducting pilot outplanting studies to establish and enhance wild populations The Aquarium of the Pacific is working with NOAA to propagate white abalone.

Image Sources: Wikimedia Commons, NOAA

Text Sources: Animal Diversity Web (ADW) animaldiversity.org; National Oceanic and Atmospheric Administration (NOAA) noaa.gov; Wikipedia, National Geographic, Live Science, BBC, Smithsonian, New York Times, Washington Post, Los Angeles Times, The New Yorker, Reuters, Associated Press, Lonely Planet Guides and various books and other publications.

Last Updated May 2023