|Scientific Name:||Haliotis cracherodii|
|Species Authority:||Leach, 1814|
|Red List Category & Criteria:||Critically Endangered A4e ver 3.1|
|Assessor(s):||Smith, G., Stamm, C. & Petrovic, F. (McGill University)|
|Reviewer(s):||Seddon, M.B., Mikkelsen, P., Roth, B. (Mollusc RLA), Haaker, P., Geiger, D. & Scott, P.|
H. cracherodii began supporting a commercial fishery in California in 1968. In the mid 1980s a wasting disease, Withering Syndrome, began to appear, reducing the commercial catch considerably. At present, the harvest of black abalone is illegal in California, but the species is still harvested commercially in Mexico. At most surveyed locations where the disease was present, black abalone populations were reduced by more than 80%. Fishers on the southern shore of Santa Cruz Island made the first observation of this disease in 1985. It has since spread throughout all the California Channel Islands and northwards to Monterey. In Mexico, cases of Withering Syndrome have been reported as far south as Cedros Island in Baja California. The spread of the disease now extends over almost the entire range of the species. Withering Syndrome does not appear to showing any signs of relenting in its progression along the coast in either direction. The strong correlation between adult abundance and recruitment suggests that larvae do not disperse very far from their point of origin, thus depleted abalone populations are unlikely to be restored by recruitment from distant populations. If no action is taken, it is estimated that H. cracherodii will decline by at least 80% over a period of three generations (from approximately 1975 to 2015), extending into the past and the future, and consequently, the species qualifies for Critically Endangered under criterion A4.
|Range Description:||The black abalone, Haliotis cracherodii, is found in intertidal waters off California, USA, and Baja California, Mexico.|
Native:Mexico (Baja California); United States (California)
|FAO Marine Fishing Areas:||
Pacific – eastern central
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Large-scale commercial fishery of black abalone began in California in 1968 (Haaker et al. 1995). Like most other abalone fisheries, black abalone landings underwent a rapid rise, peaking in 1973 at a maximum catch of over 800 metric tonnes, followed by a decline (Parker et al. 1992). In 1992, commercial landings had diminished to 17.4 metric tonnes, as a wasting disease, Withering Syndrome (WS) spread throughout southern California (Haaker et al. 1992, Haaker et al. 1995).|
|Habitat and Ecology:||
H. cracherodii is a sessile marine gastropod. It clamps tightly to rocky substrates and feeds on algal matter scraped from the rock surface. Gametes are released into the water where fertilization occurs to produce free-swimming larvae. Successful fertilization requires aggregated adults and synchronized gonad development and release (McShane 1996). After approximately 15 days as non-feeding zooplankton, the larvae metamorphose into their adult form, develop a shell, and settle onto a hard substrate (Douros 1985). Juveniles mainly reside in rocky crevices and feed primarily on benthic diatoms, bacterial films and algae found on coralline algal substrate (NMFS 2000). As juveniles, abalone are vulnerable to predators which graze the surfaces of coralline algae and associated species (McShane 1989). As they increase in size they become less vulnerable to predation and are able to emerge from their sheltered habitat and search out more desirable food sources (NMFS 2000). Adult abalone depend primarily on drift algae (Tegner and Dayton 1987). Main predators of adult abalone are fishes, otters and humans.
Most black abalone are found in the intertidal zone, ranging from the high tide line to a depth of up to five meters (Lindberg 1989).
Generation time is not easy to determine. Individuals do not display the same growth rate and older individuals may cease to grow altogether (B. Tissot, Washington University, pers comm.). Reproductive maturity is reached between three and seven years (when They are re approximately 130-150 mm in length), but life expectancy ranges from 25 to 75 years. Taking an average of these provides only a very rough estimate for the average age of parents, especially since the relationship between age and fecundity is unknown. Nonetheless, generation time is estimated to be between 14 and 41 years, thus a minimum three generation period would be 42 years (Smith et al. 2001).
Withering Syndrome (WS) is the main threat to black abalone. It is manifested by epipodial discoloration, loss of appetite, severe weight loss and atrophy of the foot muscle. As a consequence, abalone lose their ability to adhere to the substratum and eventually die (Tissot 1991, Haaker et al. 1992). The first reports of WS were in black abalone were made by fishers on the southern shore of Santa Cruz Island (Lafferty and Kuris 1993). The disease then spread throughout all the Californian Channel Islands from 1985 to 1992, except Santa Catalina Island, where no studies have been conducted (Haaker et al. 1992, Lafferty and Kuris 1993, Van Blaricom et al. 1993). At most surveyed locations black abalone were initially reduced to less than 20% of their initial densities (Tissot 1990, Davis et al. 1992, Richards and Davis 1993, Altstatt et al. 1996). Some have completely lost their black abalone populations (P. Hakker pers. comm.).
Black abalone are also affected by the large human population inhabiting southern California, the majority of which reside within 50 km of the coast (Parker et al. 1992). Coastal development, such as residential areas, harbours and coastal access points and large ocean discharges of municipal and industrial wastes contribute to the degradation and loss of near shore habitat (Parker et al. 1992). Commercial and recreational fishing have also placed black abalone populations under intense pressure. The large decline in fisheries landings may have been a consequence of over harvesting (Parker et al. 1992), however the mass mortality of populations in the Channel Islands that began in 1985 has been attributed to WS and continued fishing (Haaker et al. 1992).
Other possible threats to the species include storm, competition with other marine organisms and predation (Smith et al. 2001).
All abalone fisheries in California are managed by the California Department of Fish and Game. The restrictions employed can range from minimum legal size limits and bag limits to harvest seasons and closures (Breen 1989, P. Haaker pers. comm.). The harvest of black abalone is currently illegal in California.
In Mexico, green abalone, H. fulgens and pink abalone H. corugata are the main focus of commercial fishery. Black abalone do not form a large proportion of total abalone landings. Exclusive rights to abalone exploitation were granted to cooperative fishers' organizations. Although new legislation in 1992 allowed for the entry of the private sector into the fishery, all abalone harvesting is still done by cooperatives (Ramande-Villanueva et al. 1998). Total allowable catches per cooperative (TACCs) were introduced in 1973, but their criteria have changed appreciably over the years (Ramande-Villanueva et al. 1998). Since black abalone make up such a small proportion of the commercial catch in Mexico, it is difficult to assess the impact of these regulations on the species.
In January 1999 the National Marine Fisheries Service (NMFS) published its updated list of candidate species under the Endangered Species Act (ESA). Black abalone was one of 14 new species added to the list (NMFS 1999). The NMFS intends to conduct a review to determine whether black abalone deserves a national listing of endangered or threatened (P. Haaker, pers. comm.). Listing as a candidate species does not, however, provide substantive or procedural protection for the species under the ESA (NMFS 1999).
Stock restoration by transplantation from distant populations has been proposed to restore depleted populations (Tissot 1997). Smith et al. (2001) propose that both American and Mexican fishery authorities work together to develop a re-stocking program to help restore black abalone populations all along the coast, especially in key locations such as the Channel Islands. Since the greatest threat facing the black abalone is disease, special precaution must be taken to ensure that the transplantation of adult abalone does not create a new path for the spread of WS.
While not an especially charismatic species, many living in coastal California and Baja California recognize that the black abalone is important to local economies. A well designed public education campaign may result in a successful appeal for public funding (Smith et al. 2001).
There is a need to survey areas where the status of black abalone populations are currently unknown, namely the coastline between Los Angeles and central Baja California, in addition to new surveys being carried out at sites previously examined. A study of withered black abalone at the northern fringe of WS's current range (Monterey and San Francisco) (Smith et al. 2001).
Perhaps most importantly, further investigation of WS itself is also needed (Smith et al. 2001), including investigation into whether WS is caused by an introduced pathogen, identification of other species that may serve as reservoir hosts, and identification of resistant individuals for potential brood stock and development of husbandry.
|Citation:||Smith, G., Stamm, C. & Petrovic, F. (McGill University) 2003. Haliotis cracherodii. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>. Downloaded on 30 July 2015.|
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