Black Abalone (Haliotis cracherodii)
Did You Know?
· Black abalone is one of 7 species of abalone found in California.
Black Abalone Critical Habitat Map
(click for larger view PDF)
Black Abalone Range Map
(click for larger view PDF)
ESA Endangered - throughout its range
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|
|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.
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.
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.
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.
- 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.
Photo: Glenn VanBlaricom
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.
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.
|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|
Updated: February 27, 2013