|Scientific Name:||Acanthurus achilles|
|Species Authority:||Shaw, 1803|
Acanthurus achillas Shaw, 1803
Acanthurus aterrimus Günther, 1872
Hepatus achilles (Shaw, 1803)
Hepatus aterrimus (Günther, 1872)
Teuthis achilles (Shaw, 1803)
Teuthis aterrimus (Günther, 1872)
|Taxonomic Notes:||This species is a member of the Acanthurus achilles species complex known for their propensity to hybridize (Randall and Frische 2000). The four species in this complex (A. achilles Shaw, A. japonicus Schmidt, A. leucosternon Bennett, and A. nigricans Linnaeus) are thought to hybridize when their distributional ranges overlap (Craig 2008).|
|Red List Category & Criteria:||Least Concern ver 3.1|
|Assessor/s:||Choat, J.H., Russell, B., Stockwell, B., Rocha, L.A., Myers, R., Clements, K.D., McIlwain, J., Abesamis, R. & Nanola, C.|
|Reviewer/s:||Davidson, L., Edgar, G. & Kulbicki, M.|
Acanthurus achilles is widespread and abundant throughout its range. It is found in isolated oceanic islands and is caught only incidentally for food in parts of its distribution. It is a major component of the aquarium trade and is a popular food fish in West Hawaii. There is evidence of declines from collection and concern for the sustained abundance of this species. These localized declines are not considered to be affecting the global population. In Hawaii, where the demand for this species is high, conservation measures such as harvest management (bag limits) are being developed. Furthermore, harvest levels and and trade are closely monitored in Hawaii and this species occurs in a number of Fish Replenishment Areas in West Hawaii and a number of marine protected areas in parts of its range. It is therefore listed as Least Concern.
|Range Description:||Acanthurus achilles is found from the oceanic islands of Oceania to the Hawaiian and Pitcairn islands. It is also found in Wake, Marcus Island and the Marianas. It is also found in the Eastern Tropical Pacific from Mexico and other offshore islands such as Clipperton (Randall 2001). This species is unknown in Australia (Australian Biological Resources Study accessed 28 July 2010).|
Native:American Samoa (American Samoa, American Samoa); Cook Islands (Cook Is.); Fiji; French Polynesia (Marquesas, Society Is., Tuamotu, Tubuai Is.); Guam; Japan; Kiribati (Gilbert Is., Kiribati Line Is., Phoenix Is.); Marshall Islands; Mexico; Micronesia, Federated States of; New Caledonia; Niue; Northern Mariana Islands; Pitcairn; Samoa; Tokelau; Tonga; Tuvalu; United States Minor Outlying Islands (Howland-Baker Is., Johnston I., Midway Is., US Line Is., Wake Is.); Wallis and Futuna
|FAO Marine Fishing Areas:||
Pacific – eastern central; Pacific – northwest; Pacific – southwest; Pacific – western central
|Range Map:||Click here to open the map viewer and explore range.|
Acanthurus achilles is rare in the Marianas Islands. It is more common in the islands of Polynesia than Micronesia (Randall 2001). It is collected in several islands in the Pacific and based on visual surveys is abundant throughout its range (L. Rocha pers. comm. 2010).
In Kona, Hawaii, there was a 57% difference in abundance between control and collection sites (Tissot and Hallacher 2003). In Moorea Is., French Polynesia, it is a targeted marine ornamental fish, a total of 3,056 individuals were recorded here from 1990-1993 (Lecchini et al. 2006).
This species is one of the top 10 taxa collected for the aquarium trade in Hawaii with 337,781 individuals caught from FY 1976-2003. Catch has been in decline since FY 1990 (Walsh et al. 2004). Overall aquarium catch in fiscal years 2004 through 2006 reported 12,399 individuals caught/year and a value of $969,663/year (Friedlander 2006). In West Hawaii, 42,283 individuals were caught from FY 2005-2009 with a total value of $274,111 (Walsh et al. 2010).
There was a change in abundance recorded from nine monitoring stations in Fish Replenishment Areas (FRAs) in West Hawaii. FRAs were closed to aquarium collecting in 2000. Prior to establishment of FRAs density was recorded at 0.24 individuals/100 m2 and after establishment density was 0.15 individuals/100 m2 (Friedlander et al. 2006). There was a significant decrease in overall density across the nine Fish Replenishment Areas. However, the FRAs were shown to be effective in terms of increases inside the FRAs relative to long term marine protected areas. There was a highly variable pattern in all management areas from 1999-2005 with an overall decline from 2006-2009. Average densities of this species are very low on all transects: 0.26/100 m2. The deeper areas where the West Hawaii Aquarium Project transects are located is not the prime habitat for adults of this species. Acanthurus achilles inhabits high energy shallow surge zones. Initial results from shallow water surveys and other longer term studies suggest concern for the sustained abundance of this species. This species is a very popular food fish as well as an aquarium fish with both juveniles and adults harvested. Low levels of recruitement over the past 11 years = 0.09/100 m2 appear insufficient to compensate current level of harvest (Walsh et al. 2010).
|Habitat and Ecology:||
Acanthurus achilles is found in shallow water, generally less than about 5m, along rocky shores or coral reefs exposed to wave action. It maintains a territory very aggressively (Randall 2001). Like A. lineatus, it grazes on on algal turfs mainly on thallate and filamentous red and green algae (Choat et al. 2002, 2004). No demographic information is available for this species (J.H. Choat pers. comm. 2010).
The sexes are separate among the acanthurids (Reeson 1983). Acanthurids do not display obvious sexual dimorphism, males assume courtship colours (J.H. Choat pers. comm. 2010).
Acanthurus achilles is targeted heavily in Hawaii and there may be evidence of declines in some parts. In Kona, Hawaii, there were fewer individuals observed at collection than at control sites (Tissot and Hallacher 2003).
Surgeonfishes show varying degrees of habitat preference and utilization of coral reef habitats, with some species spending the majority of their life stages on coral reef while others primarily utilize seagrass beds, mangroves, algal beds, and /or rocky reefs. The majority of surgeonfishes are exclusively found on coral reef habitat, and of these, approximately 80% are experiencing a greater than 30% loss of coral reef area and degradation of coral reef habitat quality across their distributions. However, more research is needed to understand the long-term effects of coral reef habitat loss and degradation on these species' populations. Widespread coral reef loss and declining habitat conditions are particularly worrying for species that recruit into areas with live coral cover, especially as studies have shown that protection of pristine habitats facilitate the persistence of adult populations in species that have spatially separated adult and juvenile habitats (Comeros-Raynal et al. 2012).
In Hawaii, nine Fish Replenishment Areas were established in 2000. These areas prohibit marine aquarium organism collecting within approximately 30% of the Kona coast nearshore habitat (Kusumaatmadja et al. 2004). In 2002, the Marine Aquarium Council initiated a three-year project designed to enhance coral reef conservation in the islands by facilitating MAC certification of qualifying aquarium industry operators and encouraging market incentives (MAC 2003).
The Hawaii Division of Aquatic Resources is currently in the process of developing comprehensive package of size and bag limits. There is a recommended bag limit of 10 Achilles Tang per person per day which would apply to all harvesters including commercial fishers and aquarium collectors (Walsh et al. 2010).
|Citation:||Choat, J.H., Russell, B., Stockwell, B., Rocha, L.A., Myers, R., Clements, K.D., McIlwain, J., Abesamis, R. & Nanola, C. 2012. Acanthurus achilles. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <www.iucnredlist.org>. Downloaded on 19 June 2013.|
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