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Black Abalone (Haliotis cracherodii)

Status | Taxonomy | Species Description | Habitat | Distribution |
Population Trends | Threats | Conservation Efforts | Regulatory Overview |
Key Documents | More Info

  Black Abalone
Black Abalone
(Haliotis cracherodii)
Photo: NOAA




black abalone anatomy
Figure 1. Anatomy
(click for larger image)


black abalone lifecycle
Figure 2. Lifecycle
(click for larger image)


black abalone critical habitat map
Black Abalone Critical Habitat Map
(click for larger view PDF)


black abalone range map
Black Abalone Range Map
(click for larger view PDF)


Status
ESA Endangered - throughout its range

Taxonomy
Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
Order: Archaeogastropoda
Family: Haliotidae
Genus: Haliotis
Species: cracherodii

The white abalone (Haliotis sorenseni) is another endangered abalone.

Species Description
Weight: 1.75 pounds (800 g)
Length: 4-8 inches (10-20 cm)
Appearance:  smooth black or slate blue shell, pearly white on the inside
Lifespan: 20-30 years
Diet: kelp and algae
Behavior: while generally found wedged between rocks, black abalone will use their foot to move freely over rock, primarily when immersed in water or at night

The black abalone is a large marine gastropod mollusk found in rocky intertidal and subtidal habitats. Both their "mantle" and "foot" are black. They have 5-9 open respiratory pores along the left sides of their shell and spiral growth lines on the rear. Their tentacles, surrounding their foot and extending out of their shell, sense food and predators. Figure 1 shows the main anatomy.

Black abalone have separate sexes and broadcast spawn their eggs and sperm into the water, primarily during the summer months. They reach maturity at about 3 years old, or when they reach 1.5 inches (4 cm) in length. Figure 2 shows the typical life cycle stages.

Black abalone are herbivores. They primarily eat giant kelp and feather boa kelp in southern California (i.e., south of Point Conception) habitats, and bull kelp in central and northern California habitats.

Habitat
During low tides, these marine gastropods can typically be found wedged into crevices, cracks, and holes of intertidal and shallow subtidal rocks, where they are fairly concealed. They generally occur in areas of moderate to high surf. However, when immersed or during night time, they have been observed using their muscular feet to move freely over rock surfaces. Black abalone can withstand extreme variation in temperature, salinity, moisture, and wave action.

Critical Habitat

In September 2010, NMFS proposed critical habitat (75 FR 59900). In October 2011, NMFS designated critical habitat (76 FR 66806).

Distribution
Black abalone range from about Point Arena, CA to Bahia Tortugas and Isla Guadalupe, Mexico. Black abalone are rare north of San Francisco and south of Punta Eugenia, though unconfirmed sightings have been reported as far north as Coos Bay, OR.

Population Trends
Black abalone have experienced significant declines in abundance. It has gone locally extinct in most locations south of Point Conception, CA.

Black abalone commercial fishery landings peaked in 1973 at 868 metric tons (nearly 2 million pounds). By 1993, both commercial and recreational fisheries for black abalone closed.

Scientists estimate the abundance of black abalone prior to overexploitation and withering syndrome at over 3 million.

Threats

  • overfishing
  • withering syndrome (disease)
  • illegal harvest
  • habitat destruction

The primary factors leading to the decline of black abalone are overfishing and disease (withering syndrome). Black abalone have been important to commercial and recreational fishing in California since the mid-1800s, but it was not until the late 1970s that significant declines in black abalone populations were detected. Landings for black abalone peaked in 1973 at 868 metric tons and dropped to essentially zero in the mid 1990s. Increasing distance among potentially spawning males and females, has led to reproductive failure as the population density decreases. Evidence of localized recruitment and genetic differentiation among remaining populations exists. Decreasing population sizes have also raised concerns about genetic inbreeding and loss of genetic diversity in future populations.

A disease called withering syndrome struck black abalone populations at the northern Channel Islands in 1985. The disease is caused by a Rickettsia-like prokaryote, and full manifestation of the disease appears to be more prevalent in the southern portion of black abalone range (south of Point Conception, CA) where water temperatures are relatively warmer. Die-offs also seem to occur in habitats where water temperatures are elevated by thermal discharge of power plants.

Other factors responsible for the decline of black abalone are illegal harvest and habitat destruction.

Natural predation by a variety of predators (sea stars, the southern sea otter, and striped shore crab) as well as competition with purple and red sea urchins for space also threaten their survival.

  Black Abalone
Black Abalone
(Haliotis cracherodii)
Photo: Glenn VanBlaricom


Conservation Efforts
Existing protections include a system of California Marine Protected Areas [pdf] and commercial and recreational fishery closures. California adopted an Abalone Recovery Management Plan in 2005. Various projects are in place to monitor the species status, understand and address withering disease, improve reproduction, and minimize illegal harvest.

Regulatory Overview
Black abalone was added to NMFS Candidate Species list on June 23, 1999 (64 FR 33466). NMFS initiated an informal ESA status review of black abalone on July 15, 2003, and formally announced initiation of a status review on October 17, 2006 (71 FR 61021), at the same time soliciting information from the public. The Center for Biological Diversity formally petitioned NMFS to list the black abalone as threatened or endangered under the ESA on December 21, 2006. On April 13, 2007, NMFS found that listing of black abalone under the ESA may be warranted. On January 11, 2008, NMFS proposed listing black abalone as endangered. The species was listed as endangered under the ESA on January 14, 2009.

Key Documents
(All documents are in PDF format.)

Title Federal Register Date
Final rule to designate critical habitat 76 FR 66806 10/27/2011
NMFS proposes critical habitat for the endangered black abalone 75 FR 59900 09/28/2010
Final Rule Listing Black Abalone as Endangered under the ESA 74 FR 1937 01/14/2009
Status Review Report n/a 01/14/2009
Proposed Endangered Status 73 FR 1986 01/11/2008
90-Day Finding to List Black Abalone Under the ESA 72 FR 18616 04/13/2007
Petition to List Black Abalone Under the ESA n/a 12/21/2006

More Information

Updated: February 27, 2013

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