About the Species
Black abalone belong to a group of plant-eating marine snails that were once common in California. They once numbered in the millions along the California coast but are now endangered.
Before the time of commercial fisheries, native people along California’s coast ate 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.
Black abalone continue to live in rocky intertidal and subtidal reefs along the California and Baja California coast. They are “broadcast spawners,” releasing eggs and sperm into the water by the millions when environmental conditions are right. Their strong, muscular “foot” allows them to attach to rocks and other hard surfaces while their oval-shaped shells protect them from predators. 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.
NOAA Fisheries is dedicated to conserving and restoring black abalone. Our scientists use innovative techniques to study, protect, and restore their population. We also work with our partners to ensure that regulations and management plans are in place to reduce poaching and increase the wild abalone population.
Black abalone had been important to commercial and recreational fishing in California since the mid-1800s, and commercial fishery landings peaked in 1973 at nearly 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 disease (withering syndrome).
Long-term monitoring of black abalone populations has been conducted throughout the California coast since the mid-1970s and continues 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.
Recovering the species will involve protecting the remaining healthy populations to the north, restoring disease-impacted populations to the south, continuing long-term monitoring throughout the species’ range, and conducting research on the species’ biology and response to threats, such as disease and oil spills, to inform management and conservation actions.
- Throughout Its Range
The black abalone is a marine snail with one large, oval-shaped shell and a muscular foot used to move and to attach to rocks. The blackish-blue shell has five to nine open 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.
Behavior and Diet
Abalone are slow-moving bottom dwellers. They attach to rocks and other hard surfaces using their muscular foot and when disturbed, they become difficult or impossible to remove. An abalone can also use its foot to move across surfaces. Black abalone are generally found in rock crevices.
Adults eat different types of algae. They 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.
Where They Live
Black abalone live on rocky substrates in intertidal and shallow subtidal reefs (to about 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. Beginning in the 1980s, the spread of withering syndrome caused mass mortalities, leading to dramatic declines in black abalone 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.
Lifespan & Reproduction
Black abalone are estimated to live up to about 30 years. Adults become sexually mature in the wild when they reach about 1.5 to 2 inches in shell length.
Abalone reproduce by broadcast spawning—releasing their eggs and sperm into the water. The eggs hatch after only one day if fertilized, but large amounts of sperm are needed to fertilize an egg. This means fertilization succeeds more often when groups of adult male and female abalone are close to each other when they spawn. Fertilized eggs hatch into larvae, which later grow into adults.
Due to their unique mating habits, abalone can be depleted by intense fishing that targets groups of animals.
A commercial abalone fishery opened in California in the early 1970s, peaked in the mid-1970s, and closed in the 1990s. 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.
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.
Withering syndrome is the primary threat to black abalone. The disease is a common and fatal infection that affects the digestive organs of abalone. The pathogen that causes it is currently present in the coastal oceans of California. 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. Die-offs associated with the disease are associated with sea surface warming events (e.g., El Niño events, thermal discharges). 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.
Other abalone diseases have emerged over the past several decades in abalone populations outside of California (e.g., herpes virus, vibriosis, sabellidosis). To date, no outbreaks of these diseases have been observed in wild black abalone populations. However, black abalone may be susceptible to these diseases. Strict regulations and monitoring are needed whenever animals are imported and/or transported between facilities, to minimize the potential for introducing these diseases to wild abalone populations.
Low Densities and Reproductive Rates
One female abalone can release millions of eggs at a time—but unless the eggs come in contact with sperm from spawning males, they cannot be fertilized. 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.
Spills and Spill Response Activities
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.
Black abalone are protected under the Endangered Species Act. NOAA Fisheries is working with many partners to monitor the status and habitats of wild black abalone and protect this species in many ways, with the goal of rebuilding their populations.
Recovery Planning and Implementation
NOAA Fisheries recovery planning for black abalone is ongoing, guided by an internal recovery outline prepared in September of 2016 (PDF, 30 pages).
Once a species is listed under the ESA, NOAA Fisheries evaluates and identifies whether any areas meet the definition of critical habitat. Those areas may be designated as critical habitat through a rulemaking process. The designation of an area as critical habitat does not create a closed area, marine protected area, refuge, wilderness reserve, preservation, or other conservation area; nor does the designation affect land ownership. Federal agencies that undertake, fund, or permit activities that may affect these designated critical habitat areas are required to consult with NOAA Fisheries to ensure that their actions do not adversely modify or destroy designated critical habitat.
In October 2011, NOAA Fisheries designated critical habitat for the black abalone.
This designation includes approximately 360 square kilometers of rocky intertidal and subtidal habitat within five segments of the California coast between the Del Mar Landing Ecological Reserve and the Palos Verdes Peninsula, as well as on the Farallon Islands, Año Nuevo Island, San Miguel Island, Santa Rosa Island, Santa Cruz Island, Anacapa Island, Santa Barbara Island, and Santa Catalina Island. Within these areas, the designation refers specifically to those rocky intertidal and subtidal habitats from the mean higher high water line to a depth of -6 meters, as well as the coastal marine waters encompassed by these areas.
Monitoring Black Abalone Populations
We continue to work with many partners at Federal agencies, State agencies, universities, and non-governmental organizations to maintain and expand long-term monitoring programs to evaluate the status and health of black abalone populations. Long-term monitoring has been ongoing throughout the California coast, in some areas since the mid-1970s, providing valuable data on black abalone abundance and density trends over time. These data formed the basis for our understanding of the species’ status and will be essential for tracking the species’ recovery. Specifically, this monitoring will help the species by:
Providing data needed to measure long-term population trends and distribution.
Tracking the progress of withering syndrome along the coast, particularly during warm water events.
Detecting recruitment events, to inform our understanding of the factors affecting black abalone survival, growth, and reproduction.
Informing abalone conservation efforts, such as by providing data to evaluate the effectiveness of different restoration tools.
Boosting Abalone Populations
Black abalone populations within disease-impacted areas (e.g., southern California) remain at low numbers. Recruitment and increasing numbers have been observed in a few areas, but not at the scale or scope needed for natural recovery. Active restoration efforts may be needed to rebuild populations. We are working with partners to test the effectiveness of different restoration tools to enhance black abalone populations. These tools include:
Restoring habitat conditions to promote recruitment of juveniles;
Aggregating animals within a local area or translocating animals from one site to another to increase local numbers and the likelihood of successful reproduction; and
Developing captive breeding methods to grow black abalone for research and for outplanting to the wild, to restore abalone where they have gone locally extinct or where populations have severely declined.
Investment in disease monitoring, genetic testing and ongoing research on abalone reproduction and recruitment dynamics (e.g., how the distance between individuals affects fertilization success) will be critical to guide enhancement efforts.
Providing Public Outreach and Education
NOAA provided funding and guidance to create an interactive exhibit about abalone at the Aquarium of the Pacific. We also work with local schools in southern California, using presentations and interactive activities to share about the history and culture of black abalone and our current work to monitor, protect, and restore their populations.
NOAA Fisheries added black abalone to its ESA candidate species list on June 23, 1999. NOAA Fisheries initiated an informal ESA status review of black abalone on July 15, 2003, and a formal review on October 17, 2006. At the same time, we solicited information from the public. The Center for Biological Diversity formally petitioned NOAA Fisheries (PDF, 40 pages) to list the black abalone as threatened or endangered under the ESA on December 21, 2006.
On April 13, 2007, NOAA Fisheries found that listing of black abalone under the ESA may be warranted (PDF, 4 pages).
On January 11, 2008, NOAA Fisheries proposed listing black abalone as endangered.
The species was listed as endangered under the ESA on January 14, 2009.
Key Actions & Documents
NOAA Fisheries conducts research on the biology, behavior, and ecology of the black abalone. The results are used to inform management decisions and enhance recovery efforts for this endangered species.
Along with NOAA Fisheries, many groups—both in the United States and in other countries—are working to help save the black abalone. Among them are the Multi-Agency Rocky Intertidal Network (MARINe, www.marine.gov), Channel Islands National Park, the California Department of Fish and Wildlife, and El Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE; Baja California, Mexico).
Long-term Population and Habitat Monitoring
Long-term monitoring of black abalone populations and their habitat has been ongoing throughout the California coast, in some areas since the mid-1970s. NOAA Fisheries continues to support these monitoring programs because the data provided are critical to assessing the status and recovery of black abalone. For example, these monitoring efforts allowed researchers and resource managers to detect the mass mortalities of black abalone that occurred in the 1980s and 1990s and to track the spread of the disease through the Channel Islands and northward along the mainland California coast. Since then, continued monitoring has confirmed the local extirpation of black abalone at many sites, as well as the persistence of black abalone at several locations. Monitoring has also detected recent recruitment events and increases in black abalone numbers at a few local areas.
Efforts to expand monitoring in southern California and Baja California are underway, to fill data gaps within these regions. Future monitoring may also include genetic sampling to evaluate the population structure of wild populations and additional health monitoring to assess the level of infection with the withering syndrome disease, as well as to provide early detection of other diseases among the wild population. This long-term monitoring is only possible due to the efforts of our many partners, including Federal agencies, State agencies, universities, and non-governmental organizations, that carry out field monitoring each year and maintain and manage the data so that it is accessible to researchers and resource managers.
Disease Research and Health Monitoring
Our partners at the University of Washington, University of California Santa Cruz, University of California Davis-Bodega Marine Lab, and CDFW have made significant advancements in disease research, including the development of novel methods to detect the withering syndrome pathogen in wild abalone and their habitat, antibiotic treatments for removing the pathogen from captive abalone, correlations between increased water temperature and increased infection and disease rates, and the discovery of a bacteriophage that infects the pathogen and increases the survival of infected abalone. We continue to work with our partners to evaluate the potential for disease resistance in black abalone (through the bacteriophage and through genetically-based resistance) and the susceptibility of black abalone to other diseases.
Captive Breeding Studies
Development of a captive propagation program for black abalone would support our understanding of the early life history of black abalone, as well as provide animals for research and outplanting efforts, to enhance wild populations. The biggest obstacle, however, is the challenge of spawning black abalone in captivity. To date, successful captive spawning has been very limited and difficult to replicate. Since 2013, researchers at the Navy and now at the NMFS Southwest Fisheries Science Center have been working to develop reliable methods to captively spawn black abalone. Once methods have been developed, we can learn from the white abalone captive propagation and outplanting programs to inform development of such programs for black abalone.