Black Abalone (Haliotis cracherodii)
 Black Abalone (Haliotis cracherodii) Photo: Glenn VanBlaricom |
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Did You Know? · Black abalone is one of 7 species of abalone found in California. |
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 Figure 1. Anatomy (click for larger image)  Figure 2. Lifecycle (click for larger image) |
Status
ESA Endangered - throughout its range
Taxonomy
Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
Order: Archaeogastropoda
Family: Haliotidae
Genus: Haliotis
Species: cracherodii
Species Description
The black abalone is a large marine gastropod mollusk found in rocky intertidal and subtidal habitats. The smooth shell of the black abalone is black or slate blue on the outside with a pearly white interior. Both the "mantle" and "foot" are black. Five to nine open flush pores (respiratory pores) can be found on the left side of the shell and spiral growth lines are evident on the posterior. Tentacles surrounding the foot and extending out of the shell sense food and predators. Figure 1 shows the main anatomy.
Adults attain a maximum shell length of approximately 8 inches (20 cm), but are typically 4 to 6 inches (10-14 cm) long. Black abalone can live 20 to 30 years.
Black abalone have separate sexes and broadcast spawn their eggs and sperm into the water, primarily during the summer months. Maturity is reached at about 1.5 inches (4 cm) length or 3 years. Figure 2 shows the typical life cycle stages.
Black abalone are herbivores, feeding mostly on kelp and drift algae. The primary food species are thought to be giant kelp (Macrocystis pyrifera) and feather boa kelp (Egregia menziesii) in southern California (i.e., south of Pt. Conception) habitats, and bull kelp (Nereocystis leutkeana) 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. When immersed, and during night-time, however, this species has been observed using its muscular foot to move freely over rock surfaces. Black abalone can withstand extreme variation in environmental conditions such as temperature, salinity, moisture, and wave action.
Distribution
Black abalone range from about Point Arena in northern California to Bahia Tortugas and Isla Guadalupe, Mexico. Black abalone are rare north of San Francisco and south of Punta Eugenia, and unconfirmed sightings have been reported as far north as Coos Bay, Oregon.
Population Trends
Black abalone have experienced declines in abundance due to overfishing and a disease known as withering syndrome throughout its range and has gone locally extinct in most locations south of Point Conception, California. 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.
Threats
The primary factors leading to the decline of black abalone are overfishing and disease. 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.
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, California) 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, habitat destruction, natural predation by a variety of predators including sea stars, the southern sea otter (Enhyrda lutris), and striped shore crab (Pachygrapsus crassipes), and competition for space with purple (Strongylocentrotus purpuratus) and red (S. franciscanus) sea urchins.
Conservation Efforts
Existing protections include a system of California Marine Protected Areas and commercial and recreational fishery closures. An Abalone Recovery Management Plan was adopted by the state of California 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), and remained on this list after NMFS redefined the term "candidate species" on April 15, 2004 (69 FR 19975). 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 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 |
