White abalone - Photo: NOAA Fisheries
White abalone - Photo: NOAA Fisheries
About the Species
The white abalone belongs to a group of plant-eating marine snails that were once common in California. They once numbered in the millions off the California coast, but now they are 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.
White abalone continue to live in the coastal waters of Southern California and Mexico. 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 hold tightly to rocks and other hard surfaces while their oval-shaped shells protect them from predators. Although fishing for white abalone has been illegal in California since 1997, the high price of abalone meat makes them a target of poachers.
White abalone were listed as endangered under the Endangered Species Act 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.
NOAA Fisheries is dedicated to conserving and restoring white 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.
Population Status
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).
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.
But, while white abalone are close to extinction, efforts to breed them in captivity and reintroduce them to the wild could help the species recover.
Protected Status
Appearance
White abalone have a thin, oval-shaped shell. 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.
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.
Adults eat different types of algae. They can catch kelp drifting along the seabed or eat kelp still attached to rocks. The reddish-brown color of their shells shows that white abalone eat some types of red algae throughout their lives.
Where They Live
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). 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.
White abalone range map
Lifespan & Reproduction
White abalone live about 35 to 40 years. Adults become sexually mature in the wild when they are four to six years old.
Abalone reproduce by broadcast spawning—releasing their eggs and sperm into the water. 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 settle and grow into juveniles and adults.
Threats
Overfishing
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.
Low Reproduction Rates
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.
Disease
Abalone are also threatened by disease. Withering syndrome, one common type of infection, is a fatal disease that affects the digestive organs of abalone. The pathogen that causes it is currently present in the coastal oceans of southern California. No wild white abalone have been found to have the fatal symptoms of 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.
Scientific Classification
| Animalia |
Mollusca |
Gastropoda |
Archaeogastropoda |
Haliotidae |
Haliotis |
sorenseni |
